2015 Weed Control Guide - The Bulletin

2015 Weed Control Guide - The Bulletin
Weed Control Guide for
Ohio, Indiana and Illinois
Mark M. Loux, Doug Doohan and Anthony F. Dobbels
Department of Horticulture and Crop Science
The Ohio State University
William G. Johnson, Bryan G. Young and Travis R. Legleiter
Department of Botany and Plant Pathology
Purdue University
Aaron Hager
Department of Crop Sciences
University of Illinois
Contents
Weed Control Principles ...............................................................................................................1
Burndown Herbicide Programs for Corn and Soybeans ....................................................... 16
Burndown Herbicides in No-Tillage Corn and Soybeans ..........................................................21
Corn
Corn Herbicide Management Strategies ....................................................................................28
Preplant or Preemergence................................................................................................................. 34
Postemergence..................................................................................................................................... 47
Postemergence—LibertyLink Corn...................................................................................................61
Postemergence—Glyphosate-Resistant Corn...............................................................................62
Harvest Aid.............................................................................................................................................65
Popcorn and Sweet Corn Weed Management........................................................................... 72
Preplant or Preemergence................................................................................................................. 75
Postemergence......................................................................................................................................81
Popcorn Harvest Aid............................................................................................................................89
Postemergence—Attribute Bt11 (glufosinate-resistant) Sweet Corn........................................89
Postemergence—Glyphosate-Resistant Sweet Corn..................................................................90
Soybeans
Soybean Herbicide Management Strategies ..............................................................................91
Preplant or Preemergence................................................................................................................. 97
Postemergence......................................................................................................................................111
Postemergence—LibertyLink Soybeans........................................................................................123
Postemergence—Roundup Ready Soybeans..............................................................................124
Harvest Aid........................................................................................................................................... 126
Small Grains
Weed Management Strategies for Wheat ................................................................................ 130
Wheat Only............................................................................................................................................132
Oats and Wheat................................................................................................................................... 136
Oats and Wheat—Underseeded with Legumes...........................................................................141
Wheat: Harvest Aid..............................................................................................................................142
Figure 1. Wheat Growth Stages and Herbicide Application.....................................................143
Forages
Managing Weeds in Legumes ......................................................................................................144
Forage Legumes..................................................................................................................................147
Alfalfa: Preharvest Glyphosate Application.................................................................................. 152
Mixed Grass-Legume Forages: Established Stands Only.........................................................153
Management Strategies for Permanent Grass Pastures/CRP/Grass Hay ........................ 155
Control of Problem Weeds ..................................................................................................... 166
Control of Marestail in No-till Soybeans .............................................................................. 193
Palmer Amaranth Biology, Identification, and Management ............................................ 197
Poison Information Centers .................................................................................................... 210
Table Listing on Back Cover
1
Weed Control Principles
Importance of Weed Control
Weed control is an essential part of all crop production systems. Weeds reduce yields by competing with
crops for water, nutrients, and sunlight, and may directly
reduce profits by hindering harvest operations, lowering
crop quality, and producing chemicals which are harmful to crop plants (allelopathy). Left uncontrolled, weeds
may harbor insects and diseases and produce seed
or rootstocks which infest the field and affect future
crops. Despite large expenditures for weed control, it
is estimated that losses in U.S. crops due to weeds left
uncontrolled exceed $8 billion annually.
Years of research have shown that good weed control within the first 4 to 6 weeks after crops are planted is critical in order to avoid a yield reduction from
weeds. The efп»їfectiveness of any weed control program
depends largely upon one factor - timeliness. There are
many cultural, mechanical, and chemical methods of
weed control that are effective if applied at the correct
time. Fields that are kept free of weeds for the first four
to six weeks after planting give the crop a “head start”
which enables it to shade out or otherwise out compete
weeds that emerge later in the season.
Identify specific weed problems. Weed species
vary greatly in their ability to compete with crops and
reduce yields. Is 100% control of all weeds necessary?
Perhaps this can be answered by stating that most successful producers design control programs to maximize
profit, not just to control weeds. While it is true that
crops are able to tolerate a certain threshold number
of weeds without suffering a yield reduction, there are
some weeds for which 100% control may be desirable
because they are particularly competitive, persistent, or
difficult to control.
Cultural And Mechanical (Nonchemical) Weed Control
Herbicide performance is strongly related to environmental conditions, so not even the best herbicides are
equally efп»їfective from year to year. The most desirable
weed control program is one that will economically control existing weeds and prevent a buildup of weed seed
or tubers, rhizomes, etc. in the soil. Such a weed control
program includes integrating several crop management
practices in addition to use of herbicides.
Crop rotation is one of the most effective cultural
practices for improving long-term weed control. Crop
rotation aids in controlling weeds by: (1) allowing rotation
of herbicides as well as crops, and (2) providing the opportunity to plant highly competitive crops that prevent
weed establishment. Many herbicides available for use
in corn are extremely effective at controlling weeds for
which there are no adequate controls in soybeans or
other crops. Rotation to a densely planted crop such as
alfalfa or small grains helps control annual weeds with
little, if any, chemical input. Rotating to small seeded
legumes (e.g. alfalfa) or other densely grown perennial
grass-legume forage mixtures is efп»їfective at reducing
populations of some perennial weeds.
Any practice that promotes optimum early and
vigorous crop growth helps give crops a competitive
edge over weeds. The following are some of these
practices:
в– в– Narrow row spacings (15 inches or less) for soybeans
в– в– Proper planting date and seeding rate
в– в– Use of insect-,disease-, and nematode-resistant
varieties
в– в– Insect and disease control
в– в– Adequate soil fertility
в– в– Adequate drainage
The following are several other preventative cultural
practices that help prevent weeds from becoming established and spreading:
в– в– Control weeds in noncropland areas, including
fencerows, drainage ditch banks, and rights-of-way
в– в– Plant only high quality weed-free crop seed
в– в– Do not spread manure, hay, or crop residues contaminated with weed seed on cropland
в– в– Clean farm machinery between fields to avoid transport of weed seed, rhizomes, tubers, and rootstocks
■■If “new” or unfamiliar weeds appear, have them identified quickly and take appropriate control measures
Mechanical weed control is still an important component of many weed control programs. Primary tillage
involves moldboard plowing or some type of reduced
tillage that destroys existing vegetation and allows
adequate seedbed preparations. Secondary tillage is
performed with a tandem disk, field cultivator, or similar
implement for final seedbed preparation. Selective cultivation is performed with a rotary hoe, rolling cultivator,
shovel (sweep) cultivator, or similar implement to control
weeds after the crop has emerged from the soil.
If selective cultivation is used, it should be done
early. Rotary hoes operated at a relatively high speed (7
to 10 mph) on fairly dry soil are effective for controlling
small weeds (less than 1 inch tall). For maximum efп»їfec-
2
tiveness, a rotary hoe should be used when weeds are
in the “white stage”, or just emerging from the soil. Cultivation with a shovel, sweep, or rolling cultivator is more
effective than a rotary hoe on larger weeds, but should
still be operated when weeds are very small. Cultivations should be shallow (1 to 2 inches deep) to prevent
excessive root damage to the crop, depletion of soil
moisture, or excessive ridging, which creates problems
at harvest for some crops.
Conventional tillage systems involve primary and
secondary tillage. These operations may be followed
by selective cultivation, depending on the crop and its
row spacing. Conventional tillage is effective for reducing populations of many biennial and perennial weeds
that may may arise from rhizomes or rootstocks. Annual
weeds that reproduce only from seed will most likely still
be a problem and require additional controls.
Conservation or reduced tillage systems do not
involve moldboard plowing, and maintain some previous
crop residue on the soil surface. Tillage in a reduced
tillage system consists of using a disk, field cultivator,
or chisel plow and may be the last operation before
planting. No-till crop production involves no primary or
secondary tillage. The crop is planted directly into a sod
or the previous year’s crop residue. Conservation tillage
systems generally rely more heavily on chemical weed
control than conventional tillage systems. For additional
details on reduced tillage systems, refer to other sections of this chapter.
Chemical Control of Weeds
When designing a weed control program based on
herbicide use, consider soil type, tillage practices, crops
(current and following), weed problems, and overall
farming operations. It is important to select herbicides
based on the weeds known to be present in a field. Herbicides are often combined to control a broader spectrum of weed species, reduce carryover, or reduce crop
injury. Herbicide activity is affected by the weather, soil
conditions, weed size, accuracy of application, and other
factors.
While research has shown that weeds will not reduce
crop yields if controlled within 4 to 6 weeks after emergence, preplant and preemergence herbicides have the
advantage of eliminating weeds before they reach this
threshold. Postemergence herbicides are comparable to
soil-applied herbicides in effectiveness and economics if
applied within the same threshold period. Some weeds
are better controlled by soil-applied herbicides, while
others are more susceptible to postemergence herbicides. Consider using a program consisting of preemergence and postemergence herbicides for maximum
weed control and protection of crop yield.
Herbicide Nomenclature and Formulations
There is often more than one formulation of a particular herbicide. This can make selection and application of various products somewhat confusing. Each
herbicide has at least one trade name, a common name,
and a chemical name. For example, Lasso and Intrro are
registered trade names, alachlor is the common name,
and 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)
acetamide is the chemical name for a herbicide used in
corn and soybeans.
Prepackaged mixtures contain two or more different herbicides. For example, Bicep II Magum/Cinch ATZ
(trade names for the same product) is actually a mixture
of s-metolachlor and atrazine. For this reason it is important to know common names of herbicides so that one
knows exactly what a product contains.
Herbicides are sold in various liquid or solid formulations, depending upon (1) the solubility of the active ingredient in water, and (2) the manner in which the product is applied (i.e. dispersed in water or applied in the
dry form). The formulation type is listed on the herbicide
label and may be designated by a letter or letters following the trade name. A herbicide label must also give a
list of all herbicideally active ingredients and the amount
of active ingredient contained in the product. For liquid
formulations, the amount of active ingredient is expressed both as a percentage of the total ingredients
and as the amount of active ingredients ins in a gallon of
product. Active ingredients contained in dry formulations
are expressed only as a percentage by weight. Several
formulations and abbreviations are listed below.
Emulsifiable concentrate (E or EC) - a liquid formulation containing various emulsifiers that aid in dispersing
the active ingredient in water.
Water Soluble (S, AS, or WS) - usually a liquid formulation containing the active ingredient, water, and
sometimes a surfactant and an antifreeze agent.
Oil Soluble (OS) - a liquid formulation containing the
active ingredient dissolved in oil or some other organic
solvent. These herbicides must be applied in an oilbased carrier such as diesel fuel or kerosene.
Liquid Flowable (F or LF) - a thick liquid with a slurrylike consistency containing the active ingredient, water,
and stabilizers to help the active ingredient stay in suspension. Spray tank agitation is necessary to keep the
product from settling out of the spray solution.
Suspension Concentrate (SC) - similar to Liquid Flowable.
Wettable Powder (W or WP) - a dry powder containing the active ingredient, a diluent or carrier (usually
bentonite or attapulgite clay), and surfactants. Spray
tank agitation is necessary to keep the product from settling out of the spray solution.
3
Dry Flowable (DF) - a dry herbicide-impregnated
granules that easily disperses in water. Dry flowables are
easier to handle and measure than wettable powders.
Spray tank agitation is necessary to avoid settling.
Dispersible Granules (DG) or Water-Dispersible Granules (WDG) - a dry formulation similar to dry flowable
formulations. The ingredients are in granules that easily
disperse in water. Spray tank agitation is necessary to
avoid settling.
Granules (G) - a dry formulation consisting of the active ingredient coating or adhered to some type of inert
granule such as clay, vermiculite, or sand. These formulations are applied as a ready-to-use product. Granular
application equipment is required.
Pellets (P) - a dry formulation of active ingredient coating or adhered to some type of inert pelleted
material - similar to granules only much larger. Pellets
are applied directly to the target area by hand or with
spreaders.
Herbicide rates are sometimes expressed on an active ingredient basis in technical publications. To convert
pounds of active material to pounds of a commercial dry
formulation use:
Pounds of commercial product/A =
Pounds of active ingredient/A
Percent Active Ingredient in Product
To convert pounds of active material to gallons of a
commercial liquid formulation use:
Gallons of commercial product/A =
Pounds of Active Ingredient/A
Pounds of Active Ingredient in Gallon
Soil-Applied Herbicides
Soil-applied herbicides can be applied preplant (or
early preplant), preplant incorporated, or preemergence
to the crop. The activity of these herbicides is affected
by soil texture, organic matter content, pH, moisture,
and tillage. Soil-applied herbicides are more readily
available for plant uptake in coarse-textured, low organic matter soils than in fine-textured, high organic matter
soils. Selection of the appropriate herbicide rate is often
important to avoid injury. Many herbicide labels specify
application rates based on soil texture and organic matter content. Some herbicides are not labeled for use in
sandy soils low in organic matter.
Soil pH can influence the activity of herbicides. Triazine herbicides are more available for plant uptake in
soils with high pH, resulting in better weed control but
increased risk of crop injury. The low pH resulting from
continuous no-tillage or lack of lime application may
reduce the availability of some herbicides, causing less
effective weed control. In general, herbicides are most
effective when soil pH is in the range recommended for
optimum crop growth.
Soil-applied herbicides require adequate soil moisture for activity since uptake into germinating weeds
occurs from the soil solution only. In the presence of
adequate soil moisture, less herbicide is adsorbed onto
the soil and more is available in the soil solution for
weed control. Under dry conditions, herbicide is tightly
adsorbed by soil colloids, and insufп»їficient amounts may
be available to provide acceptable weed control. Soilapplied herbicides require rainfall (usually 1/2 inch or
more) to move them from the soil surface into the zone
where weed seed germinate and emerge.
Early preplant herbicides are applied to the soil
surface from a few weeks to more than a month prior
to planting. Herbicides with a long residual soil activity
can be applied early preplant. Herbicides with a shorter
soil residual activity may not provide late season control
when applied early. Early preplant herbicide programs
frequently do not provide adequate season-long annual grass control in fields with moderate to high grass
populations.
Advantages
в– в– Allows more time for rainfall to move herbicides from
the soil surface into the zone where weed seeds
germinate.
в– в– Herbicides can be applied with fertilizer, eliminating
field trips.
в– в– Reduces workload at planting time.
в– в– Prevents the emergence of annual weeds and eliminates the need for a burndown herbicide application
at the time of planting.
в– в– Allows more time for herbicide degradation in the
soil, reducing the risk of herbicide carryover problems.
Disadvantages
в– в– Limits herbicide options since not all herbicides have
sufficient soil residual for early application.
в– в– May require higher rates, split applications, or subsequent postemergence applications for later season
control.
в– в– May cause soil compaction from operating application equipment when soils are wet.
Preplant incorporated herbicides are mixed into the
soil prior to planting. Incorporation of some herbicides is
necessary to prevent surface-loss from volatility or photodecomposition. Other herbicides are incorporated to
reduce the dependence upon rainfall to move herbicide
into the weed seed germination zone.
4
Advantages
в– в– Reduced dependence upon rainfall to position herbicides in the soil, providing more reliable weed control
than preemergence applications.
в– в– More effective control of yellow nutsedge than with
preemergence applications.
в– в– Herbicide may be applied with fertilizer.
Disadvantages
в– в– Incorporation may result in added tillage and fuel
costs.
в– в– Incorporation can result in soil compaction and crusting.
в– в– Weed control can be reduced if the herbicide is
diluted by incorporation that is too deep.
в– в– Streaking of herbicides due to improper incorporation can result in erratic weed control.
в– в– Planting operations can be slowed due to the time
required for herbicide application and incorporation.
The depth and thoroughness of incorporation depend upon the type of equipment used, the depth and
speed of operation, soil texture, and the amount of soil
moisture. Incorporation should place the herbicide uniformly throughout the upper 1 to 2 inches of soil for best
control of small-seeded annual weeds. Slightly deeper
placement may improve control of certain weeds from
deep-germinating seeds, especially under dry conditions. The field cultivator and tandem disk place most of
the herbicide at about one-half the depth of operation,
so the suggested depth of operation for these implements is 3 to 4 inches.
Thorough and uniform incorporation, especially with
a tandem disk or field cultivator, requires two passes
at an angle to each other. However, some of the newer
combination tools can provide uniform single-pass incorporation. The effectiveness of single-pass incorporation
depends upon soil condition as much as the implement.
One-pass incorporation is not a good approach with less
than optimum soil tilth. Incorporation into soils that are
too wet can result in streaked weed control; this may
be increased with one-pass as compared to two pass
incorporation. High crop residue levels make one-pass
incorporation difficult to achieve.
Field cultivators are frequently used for herbicide incorporation. Two passes are recommended for uniform
weed control, but field cultivators can give acceptable
one-pass incorporation with proper set-up and operation. They should have 3 or more rows of shanks with an
effective shank spacing of no more than 8 to 9 inches.
Shanks can be equipped with points or sweeps. Sweeps
usually provide better incorporation, especially when
soil conditions are too wet or dry for optimum soil flow
and mixing. Sweeps for “C” shank cultivators should be
at least as wide as the effective shank spacing. For onepass incorporation, wider sweeps or narrower spacing
with a 3- to 5- bar harrow or rolling baskets will improve
uniformity of incorporation and weed control.
The recommended operating depth for the field
cultivator is 3 to 4 inches with a ground speed of at least
6 miles per hour. The field cultivator must be operated
in a level position. If the back shanks are lower than the
front, untreated soil will be brought to the surface resulting in streaked weed control.
Tandem disk harrows invert the soil and usually
place the herbicide deeper in the soil than most other
incorporation tools. Tandem disks used for herbicide
incorporation should have disk blade diameters of 20
inches or less and a blade spacing of 7 to 9 inches.
Spherical disk blades provide better herbicide mixing than conical disk blades. The tandem disk should
be operated at a depth of 3 to 4 inches with a ground
speed between 4 and 6 miles per hour. The speed
should be sufп»їficient to move the soil the full width of the
blade spacing. Two passes are recommended to obtain
uniform incorporation with a tandem disk. A leveling device (harrow or rolling baskets) should be used behind
the disk to obtain proper mixing.
Combination tools are tillage and incorporation tools
that combine disk gangs, field cultivator shanks, and
leveling devices. Many of these tools can handle large
amounts of surface residue without clogging while still
leaving considerable residue on the surface for erosion
control. Combination tools may provide more uniform
one-pass incorporation than a disk or field cultivator.
Good soil tilth is still a prerequisite for effective one-pass
incorporation. One-pass incorporation with these tools is
generally no better than two passes with a disk or field
cultivator.
Preemergence herbicides are applied to the soil surface after the crop is planted but before crop seedlings
and weeds appear above the ground. For maximum preemergence activity, 1/2 to 1 inch of rainfall should occur
within one week following application. Where this rain
does not occur, a rotary hoe is recommended for control
of weeds as they are emerging.
Advantages
в– в– Planting and herbicide application may be done in
one operation.
в– в– When rainfall is adequate to move herbicide into the
soil, preemergence applications can provide better
weed control than preplant incorporated applications.
в– в– Preemergence herbicides can be used in all tillage
systems.
5
в– в– Preemergence herbicides can be applied in liquid
fertilizers.
Disadvantages
в– в– Rainfall is required for herbicide activity
в– в– On sandy soil, heavy rains may leach the herbicide
down to the germinating crop seed and cause injury.
в– в– Perennial and deep-germinating weeds are not as
well-controlled compared to preplant incorporated
applications.
Postemergence Herbicides
Postemergence herbicides are applied after the crop
and weeds have emerged. Most postemergence herbicides have foliar activity only, while a few do provide
foliar and soil activity.
Advantages
в– в– Soil type does not affect herbicide activity.
в– в– Herbicide decisions are based on a known weed
species present at the time of application.
в– в– Postemergence herbicides can be used in any tillage
system.
Disadvantages
в– в– Application timing is critical for good weed control
and to avoid crop injury.
в– в– Weed control can be reduced if environmental
conditions cause weeds to be stressed at the time of
application.
в– в– Rain may prevent herbicide application at the proper
crop or weed growth stage.
In order to achieve effective postemergence control, it is critical to follow label recommendations on
rate and timing of applications, weed species controlled, and the use of spray additives. The rate and
timing of application are based on weed size and climatic conditions. Weeds can usually be controlled with
a lower application rate when they are small and tender.
Larger weeds often require a higher rate or an additional
herbicide or spray additive, especially if the weeds have
developed under droughty conditions. Avoid applying
postemergence herbicides during abnormally cool or
dry weather, since weeds may not be actively growing
under these conditions. Delaying application until weeds
resume active growth will ensure better control. Herbicide penetration and activity are usually greater when
the temperature and relative humidity are high, resulting
in better weed control but possibly greater crop injury.
Many postemergence herbicides can cause crop
injury. Crop size limitations are listed on product labels.
Weed control can be reduced if rainfall occurs too soon
after application. Postemergence herbicides labels
specify an interval of anywhere between 1/2 and 8 hours
between application and rainfall, depending upon the
herbicide.
The use of an adjuvant such as surfactant, crop-oil
concentrate, MSO, or fertilizer solution is often recommended to improve spray coverage and herbicide
uptake. Weed control may be increased with the use
of additives, but crop injury may be also increase. For
this reason, follow label directions regarding the use of
additives.
Other considerations for postemergence applications are spray volume, pressure, and nozzle selection.
Translocated herbicides (those that move throughout
plant) can be effective with partial foliar coverage, while
contact herbicides (active only where they contact the
plant) require more complete spray coverage. Foliar
coverage increases as spray volume and pressure increase. For contact herbicides, 15 to 40 gallons per acre
are often recommended for ground application. Translocated herbicides can often be applied in a minimum
volume of 5 to 10 gallons per acre. Minimum spray pressures of 30 to 40 psi are recommended; this pressure
range produces smaller droplets and improves penetration of dense canopies. Flat-fan nozzles are generally
preferred for postemergence applications. Most labels
do not recommend the use of low-pressure flooding
nozzles for postemergence application.
Directed Postemergence Herbicides
Directed postemergence applications minimize crop
injury because the herbicide is placed on the weeds
rather than on the crop. Precise application and a height
differential between the crop and the weeds are required for directed applications. If the weeds are smaller
than the crop, the spray can be directed at the base of
the crop so that little herbicide reaches the upper parts
of the crop plant. Spray pressure should be set fairly low
for this type of application to prevent fine spray particles
or mist. Shielded nozzles can increase the safety of applications directed at the base of the crop plants.
“Wipers” (sponge or rope wick applicators) operate above the crop canopy to control weeds growing
taller than the crop. This type of application works well
for soybeans, since weeds must generally be at least a
foot taller than the crop. Control of johnsongrass, hemp
dogbane, and volunteer corn is often achieved using
concentrated solutions of glyphosate or postemergence
grass herbicides applied in this manner.
No-Tillage Weed Control
No-till production systems are more dependent
upon herbicides for weed control than conventional or
reduced-tillage systems. In no-till, those weeds that
6
emerge from the previous fall through spring must be
controlled with fall-applied residual herbicides, or with
foliar-applied (e.g. glyphosate, Gramoxone, 2,4-D) and/
or residual herbicides applied in the spring. Spring
weed populations can consist of perennials (e.g. Canada
thistle, dandelion), winter annuals (e.g. mustards, pennycress, chickweed), and early-emerging summer annuals
(e.g. common lambsquarters, giant ragweed, Pennsylvania smartweed). If not killed at the time of planting,
these weeds often become too large to be controlled by
postemergence herbicides applied about three weeks
after planting, and may reduce crop yield.
Broadleaf weeds emerge earlier in the spring than
grasses, and application of 2,4-D with a preplant herbicide program may provide adequate burndown where
grasses are not present. Several preplant herbicides
have foliar activity in addition to soil activity, which can
control or help control small broadleaf weeds. These
herbicides include atrazine, mesotrione (Lumax, Lexar),
chlorimuron (Canopy, Valor XLT, Envive), Hornet, Balance, cloransulam (FirstRate, Gangster, Sonic, Authority
First), Python, and metribuzin. Where weeds are more
than few inches tall, or annual grasses are present, a
burndown herbicide program using paraquat or glyphosate should be considered. Glyphosate should be applied in the spring if perennial weed such as quackgrass
are present. Combinations of glyphosate or paraquat
plus 2,4-D will provide more complete control of a mixed
population of weeds than either herbicide alone.
Applying preplant herbicides earlier in the spring
when weeds have not emerged or are very small will
minimize the need for glyphosate or paraquat. Early
applications, compared to application at the time of
planting, allow more opportunity for herbicides to receive adequate rain and move into the upper few inches
of soil, However, early applications can result in poor
late-season control of some weeds, especially giant
foxtail, fall panicum, and waterhemp, especially when
crop growth is slow and rain is abundant in the early part
of the growing season. Moving herbicide application
closer to the time of planting can prevent this problem
to some extent. Preemergence herbicides applied at or
after planting can provide acceptable control in no-till,
but more rainfall will be needed for activity compred to
a conventional tillage seedbed, since herbicide must
move through crop residue to reach the soil surface.
Postemergence herbicide programs fit well into notill production systems. There can be a reduction over
time in the population of large-seeded annual broadleaf
weeds in no-till, possibly reducing the need for a broadspectrum preplant herbicide program. The application of
postemergence herbicides on an as-needed basis may
ultimately result in a reduction in herbicide inputs and
costs in no-till. Giant foxtail and waterhemp populations
often increase in no-till during the first several years, but
effective control will eventually reduce the foxtail population, due to a lack of seed return to the soil surface.
When planning a successful postemergence herbicide
program for no-till, it is essential that the field is free
of weeds at planting. Do not rely on postemergence
herbicides to control weeds that have already emerged
at planting.
A major challenge for weed management programs
in no-till is increased populations of perennial weeds,
which become more prevalent and difficult to control as
tillage is reduced. These can include hemp dogbane,
bindweeds, milkweeds, dandelion, and tree seedlings,
to name a few. Most of these emerge fairly late in the
season and cannot be killed by a glyphosate application
at planting. Likewise, most postemergence herbicides
only suppress perennials, which are more easily controlled in corn than in soybeans. The key to controlling
perennial weeds is an application of glyphosate, dicamba, and/or 2,4-D when they are in the bud to bloom
stage, or as late in the fall as possible before the weeds
senesce or growth ceases due to frost or freeze. At this
growth stage, the weeds will move herbicide throughout
the plant and into the roots, resulting in maximum kill
of the entire plant. The best opportunity for making this
type of application is during the late-summer through
fall after wheat harvest when plants have grown undisturbed for several months. Including wheat in a rotation
to allow fall herbicide applications will aid greatly in the
management of perennial weeds. Throughout the rest of
the rotation, apply burndown or postemergence herbicides as necessary to at least suppress perennials, since
this can keep infestations in check until a fall application
can be made.
Pesticide Interactions in Crops
and Weeds
When crop plants and weeds are exposed to more
than one pesticide, the effects may be described as: a)
additive - when no interaction occurs and effects on
plants are independent and predictable, b) synergistic
- when the biological activity of the pesticide mixture
is greater than the sum activity of its individual components, or c) antagonistic - when the biological activity of
the mixture is less than the sum activity of its individual
components. Interactions of pesticide combinations in
crops or weeds may be due to an alteration in the uptake, translocation, or metabolism of one or more of the
active ingredients. The response of crops and weeds to
7
pesticide mixtures is highly species-dependent. A given
mixture might be synergistic in a weed while showing no
adverse effects on the crop or vice-versa.
herbicide. Where the grass herbicide is applied first, the
waiting period is usually only a day or so.
Herbicide Antagonism
Herbicide-insecticide interactions are of special
concern because they usually result in synergistic action
and injury to crop plants. Crop injury results because
some insecticides temporarily render crop plants unable
to metabolize and detoxify herbicides that otherwise
cause little or no injury. Application of some organophosphate corn rootworm insecticides (Thimet, Lorsban,
etc) in combination with or followed by treatment with
ALS inhibitor herbicides (Accent, Beacon, Lightning,
Option, Steadfast, etc.) can injure corn. Symptoms of this
injury include stunting, yellowing, and a failure of the
corn leaves to properly unfurl.
The severity of injury is dependent upon environmental conditions, the insecticide used, and the method
of insecticide application. Injury is most likely when
insecticides are applied in-furrow, rather than T-banded.
Thimet is the insecticide that tends to cause the most
problems, especially when applied in-furrow. Some herbicide labels prohibit application where Thimet has been
or will be applied to corn, while others prohibit in-furrow
application.
Most research indicates that injury from a herbicideinsecticide interaction is likely to be most severe when
rain is adequate to ensure effective insecticide and
herbicide uptake and activity. Some studies have shown
that significant rain during the week prior to the postemergence application of an ALS inhibitor increases the
severity of injury. Injury may be more likely when the
corn plant is under stress from weather or a previous
herbicide application. However, conditions suitable for
rapid crop growth following injury will provide an opportunity for the crop to outgrow injury.
To avoid problems with herbicide-insecticide interactions, make sure the use of an insecticide is warranted
based on scouting or cropping history. Pyrethroid-type
insecticides (Force, for example) do not increase the risk
of injury from an herbicide, and can be substituted for
organophosphate insecticides where use of an insecticide is warranted. Applying an organophosphate insecticide in a T-band rather than in-furrow can minimize the
risk of injury. See Tables 11 and 12 for a list of restrictions
on insecticide use for ALS-inhibiting herbicides.
When two or more herbicides are mixed together,
the result can be a reduction in the activity of one of the
herbicides on certain weeds. This is known as herbicide
antagonism. The most common example of this is the
reduction in grass control that can occur in soybeans
when postemergence grass herbicides (Assure II, Fusion, etc) are mixed with postemergence broadleaf herbicides. The degree of antagonism is dependent upon
the grass species as well as the herbicides applied.
Antagonism rarely is a problem when volunteer corn
or shattercane is the target grass, but tends to occur to
some degree for giant foxtail, and can be a severe problem when the target grass is yellow foxtail or a perennial
such as johnsongrass.
While all postemergence broadleaf herbicides are
capable of causing antagonism to some degree in
soybeans, those most likely to do so are Pursuit, Classic, Basagran, Raptor, Scepter, FirstRate, Synchrony, and
HarmonyGT. Mixtures of postemergence grass herbicides with Pursuit are generally labeled for control of
volunteer corn and shattercane only. Classic, Basagran,
Synchrony, and HarmonyGT can be mixed with grass
herbicides for control of certain grasses only (including
giant foxtail), but an increased rate of the grass herbicide may be required. When grass plants are stressed
and herbicide activity is reduced, the control of grass
from Pursuit and Raptor can be reduced when mixed
with Cobra and other contact herbicides. Herbicide
labels generally indicate the grass herbicide rates required and grasses controlled when they are combined
with other herbicides. Antagonism can sometimes be
reduced by using different spray additives or including
UAN or AMS in the spray mixture.
Antagonism between postemergence grass and
broadleaf herbicides is most likely to occur when grasses are stressed due to cold or dry conditions and not
actively growing. Antagonism will also tend to be more
evident when grass size exceeds that indicated on the
herbicide label. To minimize antagonism, apply the herbicides when grass size is well within label guidelines
and make the application when conditions are favorable
for active plant growth. Applying herbicides separately
is the most effective method for avoiding problems with
antagonism. However, antagonism may still occur when
the grass herbicide is applied too soon after the broadleaf herbicide. In general, allow 7 days after the broadleaf herbicide application before applying the grass
Herbicide - Insecticide Interactions
Herbicide Use Precautions
Herbicides, like all pesticides, should be handled with
extreme care and respect in order to protect the applicator and others from poisoning, to protect the environment, and to avoid crop injury. Labels provide specific
8
safety suggestions and requirements for handling particular products. The following are general guidelines to
reduce the risks from herbicides.
в– в– Apply herbicides only to those crops for which use
has been approved.
в– в– Clean tanks thoroughly when changing herbicides,
especially when using a postemergence herbicide.
Most postergence herbicide labels contain specific
instructions for sprayer clean out.
в– в– Correctly calibrate the sprayer and check the nozzle
output before adding herbicide to a tank.
в– в– Use recommended rates. Applying too much herbicide is costly, may damage crops, and is against the
law. Using too little herbicide can result in poor weed
control.
в– в– Apply herbicides only as specified on the label.
Observe the recommended intervals between application and livestock pasturing or crop harvesting.
Observe the recommended interval between application and planting of follow crops
в– в– Wear goggles, rubber gloves, and other protective
clothing as suggested by the label.
в– в– Guard against drift injury to nearby susceptible
plants, such as ornamental, vegetables, or other
agronomic crops.
в– в– Apply herbicide only when all animals and persons
not directly involved in the application have been removed from the area. Avoid unnecessary exposure.
в– в– Check the label for the proper method of container
disposal. Triple rinse, puncture, and haul metal containers to an approved sanitary landfill. Deposit paper
containers in a sanitary landfill or burn them in an
approved manner.
в– в– Promptly return unused herbicides to a safe storage
space. Store them in original containers away from
unauthorized persons, especially children. Keep storage areas locked.
в– в– Formulations and labels are frequently changed and
government regulations modified, so always refer to
the most recent product label.
Sprayer Calibration
Proper application of herbicides helps ensure crop
safety, weed control performance, and cost efficiency.
For these reasons, calibration and maintenance of
spray equipment are essential. Over-application of
herbicides is costly and may result in crop injury or
carryover. Under-application may result in poor weed
control. Similarly, sprayers that are not well-maintained
may deliver an uneven spray pattern, resulting in weedy
“streaks” throughout the field.
The procedures for maintaining and calibrating spray
equipment are really quite simple and consist of two major steps: (1) selection of the proper nozzle tip, and (2)
calibrating the equipment to deliver the correct amount
of spray.
Selecting the Proper Nozzle Tip
Many different nozzle tips are available for applying
herbicides, and a number of new tips have been introduced recently that can greatly reduce spray drift. With
the exception of drift concerns, almost any nozzle can
be used to apply preemergence herbicides to tilled soil
when control of emerged weeds is not a concern. However, nozzle selection is more of a concern for application of postemergence herbicides to emerged weeds.
Nozzles that result in relatively large droplets can work
well for glyphosate and other translocated herbicides,
but should generally be avoided with contact herbicides.
For example, two nozzles that reduce drift, the Turbo
Teejet and AI (air induction) Teejet nozzle, are rated
excellent for translocated herbicides but only good
for contact herbicides in the Spraying Systems nozzle
selection guide.
Droplet size is an important consideration when applying herbicides alone or in combination with fungicides or insecticides. The recommended droplet size for
fungicides is 150 – 250 microns: insecticides, 200-300
microns:;contact herbicides, 250-400 microns; and
translocated herbicides, 400 microns or higher. Droplet
size will influence herbicide efficacy, and the recommedned ranges should be used as a guide to select
the appropriate nozzle and spray pressure to maximize
performance. Consult technical information from nozzle
manufacturers or a professional with knowledge of
spray technology for more information on proper nozzle
selection and use and appropriateness of herbicide
mixtures with insecticides or fungicides.
Nozzles on the spray boom should be spaced according to the equiment manufacturers’ recommendations, because the correct amount of spray overlap
between adjacent nozzles is critical to achieve a uniform
spray pattern. For the same reason, it is important that
the height of the boom and pressure be adjusted according to the manufacturers’ recommendations. The
pressure and size of the nozzle tip orifice determine the
spray output, so nozzle tip sizes should be matched with
the desired spray application rate and ground speed.
Nozzle tip manufacturers have selection guides that
simplify this process.
Nozzle tips are available in a variety of materials,
which vary considerably in price and wear life. The
most common materials are hardened stainless steel,
stainless steel, thermoplastics, and ceramics. Hardened
9
stainless steel is the most wear-resistant material, but it
is also the most expensive. Stainless steel, ceramic, and
hardened stainless steel tips have excellent wear-resistance with abrasive or corrosive materials (e.g. wettable
powders, liquid fertilizer solutions). Thermoplastic tips
have shown good resistance to abrasion and corrosion,
but may vary in wear life depending on the specific material used to mold the tips.
In general, flat fan or extended range flat fan nozzles
give the most satisfactory performance over a wide
variety of conditions. Nozzles placed on 15- to 30-inch
spacings, with the height and angle adjusted to give
100% overlap, provide uniform coverage and some insurance against pattern skips in the event of a plugged
nozzle or boom rocking in rough terrain. Do not angle
tips more than 30 degrees from vertical as the drift potential greatly increases. For floaters and sprayers with
boom heights greater than 3 feet, 80 degree flat fan tips
are recommended. For lower boom heights, 100 degree
tips are recommended. The 110 degree tips are needed
to maintain 100% overlap at lower boom heights. For
farmer application with lower boom heights and 110
degree tips, recommended nozzles types include
extended range flat fan, Turbo TeeJet, air induction (AI),
and Turbo Floodjet.
Formula for Nozzle Tip Selection and Calibration
A single formula may be used both for nozzle tip
selection and sprayer calibration. The formula is:
GPM (per nozzle) = GPA x MPH x W
5940
Where:
GPM = required output per nozzle in gallons per minute
GPA = desired total carrier volume in gallons per acre
MPH = desired ground speed in miles per hour
W = space between nozzles in inches (or band width if
making band applications)
A. Nozzle tip size (orifice) selection:
Select a nozzle that will give the required flow rate
when the nozzle is operated within the recommended
pressure range. Recommended carrier volumes (GPA)
are specified on herbicide labels and typically range
from 10 to 40 gallons per acre. Ground speed (MPH)
should be accurately determined, since speedometers
on many tractors are unreliable.
B. Measuring ground speed:
Mark off a distance of 200 feet in the field to be
sprayed or in a field with similar surface conditions. At
the engine throttle speed (rpm) and gear to be used for
actual spraying, determine the time required to travel
the 200 feet. Use the table below to determine actual
speed in MPH.
Time (seconds) required to
travel 200 feet
45
39
34
30
27
23
19
18
17
15
14
Speed in MPH
3.0
3.5
4.0
4.5
5.0
6.0
7.0
7.5
8.0
9.0
10.0
C. Calibrating the sprayer
Install the selected nozzle tips in the sprayer. Using
only water in the tank, turn the sprayer on and collect
the output from a single nozzle for one minute in a container marked in ounces. The number of ounces collected in one minute can be converted to GPM by dividing
by 128 (1 gallon = 128 ounces). If the GPM collected from
the nozzle is below that required by the above formula,
then increase the spray pressure. Decrease pressure if
the output is too large. Check each nozzle separately for
the correct output. Ideally, they should all be within 5%
of the correct output.
Maintaining Spray Equipment
Check nozzle flow rates frequently and adjust the
pressure to compensate for small changes in nozzle
output resulting from normal wear. It is also important to
recalibrate each time a different material is applied - for
example, when changing from application of a wettable
powder to a soluble liquid product, or from a water carrier to liquid fertilizer. Since each of these spray mixtures
have different densities, actual flow rates can be quite
different at a single pressure setting. Replace nozzle tips
and recalibrate when output has changed 10% or more
from that of new nozzle tips or when the spray pattern
becomes uneven.
Cleaning Spray Equipment
Clean sprayers immediately after use. Most herbicides will injure crops other than those for which they
are labeled, and small quantities of herbicides remaining in the sprayer from a previous application can cause
extensive damage to the next field sprayed. The amount
10
of these products in the spray lines, filters, sumps, tank,
or screens can be sufficient to injure nonlabeled crops
even when diluted by refilling the tank. Sprayer contamination can be more of a problem with plastic or poly
spray tanks, compared to stainless steel, since small
amounts of some herbicides can adhere to the plastic.
These herbicides can then be released from the tank
walls when UAN or solvent-based herbicides are used in
subsequent applications.
Use of water alone is usually not sufficient to adequately clean spray tanks, especially for glyphosate,
growth regulator herbicides, or many low-rate translocated herbicides. Labels for these products generally
recommend use of household ammonia or a commercial
tank cleaner. The labels of postemergence herbicides
contain specific instructions on clean out procedures
for a specific product. A publication titled "Cleaning
Field Sprayers to Avoid Crop Injury" (Publication G4852)
contains a concise summary of the cleanout procedures
for most products, and is available on the web at http://
muextension.missouri.edu/xplor/aguides/crops/g04852.
htm.
The following is an example of a thorough sprayer
cleanup procedure:
1. Drain sprayer and spray tank completely from the
lowest point.
2. Thoroughly hose down the interior surfaces of the
tank. Flush the tank, boom, and hoses with clean
water for a minimum of 5 minutes.
3. Partially fill the tank with water and add household
ammonia (one gallon per 100 gallons of water) or
a commercial tank cleaner (follow label directions).
Completely fill the tank with water, then flush the
cleaning solution through the boom, hoses, and
nozzles, and drain the system from the lowest point
again. Then go to 4a or 4b.
4a. When spraying crops that are relatively tolerant to
the product used in the previous load, add water to
completely fill the tank again, and allow to agitate or
recirculate for at least 15 minutes. Flush the boom,
hoses, and nozzles again, and drain the system from
the lowest point.
4b. If growth regulators were used and sensitive crops
will be sprayed next, add more water and ammonia to the spray tank, agitate or recirculate, flush a
portion of the solution through the booms, hoses
and nozzles, and let the solution sit in the sprayer
overnight.
5. Remove the nozzles and screen, and clean separately in a bucket containing water and the cleaning
agent.
6. Thoroughly rinse the tank with clean water for a
minimum of 5 minutes, flushing water through the
boom and hoses. This procedure may need to be
preceded by a pressure wash or steam cleaning of
the tank to help remove caked deposits. To prepare
spray equipment for storage over the winter, disconnect all hoses and allow the water to drain out. Coat
bare metal parts with oil or a rust inhibitor. Disassemble metal nozzles and store in oil. Prepare the
spray pump for storage based on the manufacturer’s
recommendations.
Compatibility of HerbicideFertilizer Combinations
Many soil-applied herbicides can be applied using
fertilizer solution as the carrier. The compatibility of the
components of these mixtures is critical, and should be
tested prior to application even though product labels
allow mixing. Most labels contain instructions for testing
the compatibility of herbicides with fertilizer solution.
Follow label directions closely when applying these
combinations.
Testing for compatibility requires a glass jar and the
herbicides and liquid fertilizer to be mixed. Place one
pint of liquid fertilizer in the jar and add two teaspoons
of the liquid herbicide. If the herbicide is a dry formulation, mix two teaspoons of herbicide with sufficient
water to form a slurry, and add the slurry to the fertilizer.
Cover the jar, shake well, and observe the mixture for
30 seconds. Check the mixture again after 30 minutes.
If the mixture does not separate, it is compatible. Each
batch of liquid fertilizer should be checked, as they vary
in mixing properties. The pH and mineral content of
water will also influence compatibility.
If more than one herbicide is to be mixed with water
or liquid fertilizer, the herbicides should be premixed in
liquid fertilizer or water and tested for compatibility by
mixing appropriate proportions of all components. The
combination should be thoroughly agitated before each
additional herbicide is added, and a specific mixing
order followed. Unless label directions state otherwise,
add the herbicide to water or fertilizer in the following
order:
1. wettable powders or dispersible granules,
2. flowable or aqueous liquids (solutions),
3. emulsifiable concentrates,
4.COCs.
Spray tanks should be at least half filled with the
carrier before the herbicides are added. Compatibility
agents are available to improve compatibility. If the mixture foams excessively, separates, or becomes syrupy,
do not apply. Even if all components appear compatible,
the tank mixture will require constant agitation to prevent separation or poor distribution in the tank. Be sure
11
the entire tank mixture is agitated before spraying. Do
not store tank mixtures of herbicides for long periods or
overnight without constant agitation. Best results will be
obtained by applying tank mixtures promptly.
Off-Target Movement of
Herbicides
Spray drift is the downwind movement of spray particles from the application site to non-target areas, some
with sensitive plant species. The extent of spray drift
increases as (1) the size of spray droplets decreases, (2)
the height above the ground from which the droplets
are released increases, and (3) wind speed increases.
Drift can be minimized by following these guidelines.
в– в– Spray when wind speed is low.
в– в– Use the maximum nozzle orifice size without distorting spray pattern.
в– в– Reduce spray pressure to the lowest setting without
distorting spray pattern.
в– в– Using nozzles that minimize drift, such as Air Induction, Turbo Teejet, or Flat Fan DriftGuard nozzles.
в– в– Use drift control agents when permitted by the label.
в– в– Follow label precautions for drift reduction measures.
Volatility and vapor drift is the tendency of an herbicide to vaporize and drift through the air as a gas. A
herbicide with a high vapor pressure has a greater tendency to volatilize than one with a low vapor pressure.
Application of Command is prohibited near sensitive
plants because of the phytotoxicity of spray particles
and vapors. Dicamba and the ester formulations of 2,4-D
may vaporize at temperatures as low as 70В°F and move
with prevailing air currents to areas with sensitive plants,
including ornamentals, soybeans, and vegetable crops.
Amine formulations of 2,4-D are essentially nonvolatile.
The volatility of dicamba varies with the formulation.
Clarity and Distinct are less volatile than Banvel, but still
have some potential to volatilize.
The rate of herbicide volatilization increases with
increasing temperature. In the summer, temperatures at
the soil surface may exceed 140В°F on a clear day, greatly
enhancing conditions for volatility. Vapors drift farther
and over a longer period of time than do spray droplets.
Changes in temperature and wind direction following
application can move damaging vapors to sensitive
plants. To avoid vapor drift, carefully observe label precautions when applying a volatile herbicide.
Herbicide Carryover
The length of time an herbicide remains active in the
soil determines the period of weed control that can be
expected through the current growing season and the
potential for carryover to the following year. Although
most herbicides dissipate within the same growing season in which they are applied, some herbicides persist
longer than others and may be especially harmful to
specific crops grown next in the rotation. The overall
potential for carryover is a function of the herbicide, the
accuracy of application, the rotational crop grown, and
the environmental conditions following herbicide application.
Degradation of most soil-applied herbicides is the
result of chemical and microbial breakdown processes.
The rate of degradation increases with soil temperature, and degradation requires adequate soil moisture.
Because a large portion of the herbicide is degraded in
the summer and early fall following application, very dry
conditions during this period will increase the potential
for carryover of many herbicides.
The rotational crop is more likely to show injury
symptoms from herbicide carryover if it is not tolerant to
the herbicide or weakened by stress from adverse climate, disease, or nutritional deficiencies. Yield reduction
from herbicide carryover injury is more likely to occur
if adverse growing conditions continue throughout the
growing season.
Herbicide carryover is also influenced by herbicide
rate, distribution, soil type, soil pH, and timing of application. While most herbicides are safe to rotational crops
when applied at normal use rates, higher rates in areas
of fields where herbicides are not uniformly distributed
may result in carryover problems. Poor distribution is
generally the result of improper calibration, poor agitation, sprayer overlaps, or non-uniform incorporation.
Longer intervals between herbicide application and
rotational crop planting allow the herbicide more time
to degrade, thus reducing the risk of carryover. Delayed
planting the year following application reduces the probability of injury from carryover. Where double cropping
or intercropping practices are used, carryover problems
may increase due to the number of crops planted within
a fairly short period of time.
Herbicides are more persistent in fine-textured, high
organic matter soils than in coarse-textured, low organic
matter soils. The soil’s absorptive capacity for herbicide
increases as organic matter and clay content increases.
Because microbial and chemical degradation reactions
occur mainly in the soil solution, absorption of herbicide
on soil can “protect” the herbicide from breakdown.
However, adsorption also reduces the availability of herbicide for plant uptake, so increased persistence may
not always result in an increased carryover injury.
The persistence of some triazine (atrazine) and sulfonylurea (chlorimuron, prosulfuron) herbicides is longer at
high soil pH than at low pH. The persistence of Scepter
12
and Command is longest at low pH (<5.9). Follow label
directions regarding the application of herbicides and
soil pH.
The sensitivity of a crop to an herbicide affects the
potential for carryover injury. Vegetable and ornamental
crops are generally more sensitive to herbicide carryover than field crops. Within a specific crop, some
varieties are more tolerant of a given herbicide than
others. Herbicide labels contain restrictions regarding
the interval that must occur between application of a
herbicide and the planting of rotational crops.
Guidelines To Avoid Carryover Problems:
1. Select the appropriate herbicide rate based on soil
type.
2. Calibrate the sprayer and apply herbicide accurately
and uniformly.
3. If incorporating, make sure it is done thoroughly and
uniformly.
4. Consider applying reduced rates of a persistent herbicide in combination with a less persistent herbicide.
5. Select herbicides based on rotation plans. Follow the
recrop restrictions on herbicide labels.
6. Apply the herbicide as early as possible and delay
planting of the rotational crop if carryover is suspected.
Testing for Herbicide Residues
In fields where a carryover problem is suspected,
bioassays or soil tests may be performed to determine
if unacceptable levels of herbicide residue are present. With a bioassay, one or more sensitive species are
grown in the “suspect” soil and compared to the growth
in “check” soil not treated with an herbicide. This comparison makes it possible to separate carryover injury
from injury caused by plant disease, environmental
stress, or lack of soil moisture. It may be necessary to
bioassay soils with the plant species that will be planted
in the “suspect” field. For suspected triazine carryover, a
bioassay using oat plants is often effective. For sulfonylurea (e.g. Classic) and imidazolinone (e.g. Scepter),
herbicides, corn can be an effective bioassay species.
These classes of herbicide chemistry inhibit corn root
growth, so it is important to observe root growth when
conducting a bioassay.
Samples for bioassays should be taken from the
field in early to mid-spring, leaving enough time to observe the effects before making a recrop decision. The
method of sampling can be critical. A group of samples
mixed together may not be accurate because the resulting average will not show whether “hot spots” of high
herbicide concentration exist. Where soil has been
moldboard plowed, sample to the depth of tillage (about
6 inches). In no-till or where soil has been chisel plowed,
herbicides remain more concentrated in the upper few
inches of the soil, and samples should be taken from
fairly shallow depths (about 3 inches).
Commercial laboratories will test soil samples for
herbicide residues, but the procedure can be expensive. The interpretation of test results is difficult since
carryover potential depends upon both the actual
herbicide concentration detected and the availability of
the herbicide to plants. The availability of an herbicide
varies with soil texture, organic matter content, and
moisture. For the triazine herbicides and others that
have been used for a number of years, it is possible to
estimate carryover potential from test results. For some
of the newer herbicides, a lack of information in general
may preclude meaningful interpretation of test results.
The following table provides a rough guideline for
planting various crops based on laboratory soil test
results for triazine residues.
Triazine Residue Level
3 inch sample
(no-till)
6 inch sample
(moldboard plow)
“Safe” to
plant
less than 0.17 ppm
less than 0.08 ppm
oats, alfalfa
0.17 to 0.35 ppm
0.08 to 0.17 ppm
soybeans
greater than 0.35 ppm greater than 0.17
corn
Avoiding Water Contamination
Surface Water
Traces of several common herbicides have been
found in some municipal water sources in Ohio, Illinois,
and Indiana. Herbicides and other pesticides can reach
streams, lakes, and reservoirs from treated fields when
dissolved in runoff water or adsorbed onto the surface
of eroded soil particles. Runoff risk is greatest when
heavy rains closely follow herbicide application to fields
with steep slopes. Surface water quality can be protected by reducing water runoff and soil erosion from
treated fields.
Conservation tillage systems generally reduce water
runoff and soil erosion compared to conventional tillage
due to the crop residue remaining on the soil surface.
Incorporating herbicides may reduce runoff potential
by reducing the concentration of herbicide on the soil
surface. Grass strips are somewhat efп»їfective in reducing
herbicide runoff because they trap sediment carrying
herbicides and slow runoff water, allowing more herbicide to fall out of solution. Leaving untreated grass strips
13
next to streams and ponds will help protect water quality. Never clean or dump sprayers or dispose of empty
containers near streams, ponds, or lakes due to the risk
of contamination.
Some herbicide labels contain a surface water advisory stamement, indicating they may have a potential
for runoff into surface water under some conditions. All
products containing sulfentrazone, atrazine, isoxaflutole,
flufenacet, diflufenzopyr, terbacil, mesotrione, pyroxsulam, foramsulfuron, saflufenacil, terbacil, tembotrione,
and cloransulam-methyl have this advisory.
Groundwater
In Ohio, Illinois, and Indiana, the groundwater contamination from herbicides is minor compared to many
other states. However, herbicide users should be aware
that groundwater can become contaminated by herbicides. Most instances of groundwater contamination are
due to leaching of herbicides from loading or disposal
sites. The potential for groundwater contamination can
be reduced through careful application, handling, and
storage of herbicides.
Leaching. While the majority of herbicide applied
generally remains in the top few inches of soil and
degrade, a small percentage of certain herbicides can
leach below the root zone to possibly contaminate shallow groundwater. This is most likely to happen in sandy
soils, which have a low capacity for absorbing herbicide.
Herbicides are less likely to leach if they have low water
solubility, are strongly absorbed on soil particles, or are
fairly nonpersistent. Conversely, herbicides that are high
in solubility, weakly absorbed on soil, and very persistent are most likely to leach.
The potential for groundwater contamination can
be reduced by selecting and using herbicides with low
leaching potential. This is especially important where
soils are sandy. Applying lower herbicide rates and
reducing the total amount applied, as in banding, can
lower contamination potential.
Groundwater warning statements are required on the
labels of herbicides that have been detected frequently
in groundwater monitoring. Most groundwater statements have a similar wording: “This product is a chemical which can travel seep or leach) through the soil and
can contaminate groundwater which may be used as
drinking water. This product has been found in groundwater as a result of agricultural use. Users are advised
not to apply this product where the water table (groundwater) is close to the surface and where soils are very
permeable, i.e., well drained soils such as loamy sands.
Your local agricultural agencies can provide further information on the type of soil in your area and the location
of groundwater.”
All products containing any of the following active
ingredients are labeled with a groundwater advisory
statement:
acetochlor
alachlor
isoxaflutole
atrazine
metolachlor
flufenacet
cyanazine
clopyralid
diflufenzopyr
metribuzin
flumetsulam
terbacil
simazine
dimethenamid
hexazinone
sulfentrazone
cloransulam-methyl saflufenacil
tembotrione
sulfosulfuron
lactofen
tebuthiuron
halosulfufon
Leaching from mixing or disposal areas. High soil
herbicide concentrations occur through spillage or
improper disposal of herbicides in small areas. These
high concentrations can overload the ability of the soil to
adsorb and degrade herbicides. Leaching of herbicides
from these areas is much greater than in treated fields.
If sprayers are drained or cleaned out in the same place
over years, concentrated sources of herbicide are created. If this activity takes place near a well, contamination
risks increase, especially if the well is not properly cased
allowing surface runoff to enter the well. Herbicides
should be stored and mixed away from a water well.
The best method to dispose of excess spray mixture
and rinsate is to use them on a crop field. The excess
can sometimes be applied at low rates on a portion of
the field by increasing sprayer speed or diluting the
mixture with additional water. Be careful not to exceed
the total label rates for the crop, risking crop injury, carryover, or illegal applications.
Backsiphoning into wells can allow large quantities
of herbicide to directly enter groundwater. This happens
when the end of the water hose is allowed to extend
into the spray solution when filling sprayers. If the water
is shut off with the hose in the tank, the spray solution
can backsiphon down the well or into the water system.
To avoid backsiphoning, position the hose above the
spray solution while filling and remove the hose prior to
shutting off the water. Use an anti-backflow valve when
drawing water from a well or pond. Inexpensive antibackflow devices for hoses that are used to fill sprayers
can be purchased from sprayer equipment dealers. A
state regulation in Ohio requires an anti-backsiphoning
device in certain sprayer systems.
Herbicide Resistance in Weeds
A number of crops and weeds exhibit tolerance to
some herbicides by preventing their absorption and/or
translocation, or by rapidly metabolizing the herbicide
to a non-toxic form. These are the basic mechanisms of
14
herbicide selectivity upon which modern herbicide use
is based. Herbicide-resistant plants have biochemical
differences in the site of action normally attacked by a
herbicide in susceptible plants, thus leaving them unaffected by the herbicide. In weed populations throughout
the world, large populations of single weed species can
contain a relatively small number of biotypes that have
slight genetic difп»їferences from the rest of the population. Experience since the herbicide revolution began in
the 1940s indicates that some naturally occurring weed
biotypes can be resistant to herbicides that are normally
lethal to the majority of the population.
The phenomenon of resistance can be explained as
follows. When the same herbicide or herbicides having
the same site of action (for example, a photosynthesis
inhibitor) are applied to an area repeatedly over time,
the portion of a weed population susceptible to that
herbicide is gradually depleted. This creates an opportunity for other weeds naturally resistant to that herbicide (including resistant biotypes of species normally
susceptible to the herbicide) to become established. If
the same herbicide or others with an identical site of
action are applied on a year-to-year basis, there is no
interruption of the resistant weeds’ yearly reproductive
cycle, and the population will continue to expand rapidly
over time.
Common lambsquarters and pigweed species are
examples of weeds that have developed populations
resistant to the triazine herbicides. In Ohio, triazineresistant populations are most prevalent in areas where
atrazine and/or simazine have been applied annually
in continuous corn-growing areas. Some wild carrot
populations have developed resistance to 2,4-D in
Ohio. Elsewhere in the United States, there are reports
of triazine-resistant velvetleaf, triazine-resistant giant
foxtail, dinitroaniline-resistant goosegrass, and ACCase
resistant giant and green foxtail and johnsongrass. More
recently, there is growing concern because of reports
that some weed biotypes are showing resistance to the
newer herbicides, especially ALS inhibitors. The latter is
of special concern because both classes of herbicides
attack exactly the same site of action in plants, and evidence is growing that weeds resistant to imidazolinones
may also be resistant to sulfonylureas and sulfonamides,
a phenomenon known as cross-resistance. Populations
of several weeds in Ohio, Illinois, and Indiana have
developed resistance to ALS inhibitors, including: giant
and common ragweed, horseweed (marestail), waterhemp, cocklebur, Powell amaranth, smooth pigweed,
and shattercane. More recently, populations of horseweed (marestail), waterhemp, palmer amaranth, and giant and common ragweed with resistance to glyphosate
have been identified in Illinois, Indiana and Ohio, and
some populations are resistant to both glyphosate and
ALS inhibitors.
Prevention is the key to avoiding development of
herbicide-resistant weed populations in agricultural land.
The following management techniques help keep resistant populations from developing:
Crop rotation - Some weed problems are more easily
managed in some crops than others because different
control options may be available. Crop rotation also
helps disrupt weed life cycles and helps prevent any
single weed species from becoming firmly established.
Herbicide rotation - Herbicide rotation is generally
practiced along with crop rotation, and as long as herbicides used in one crop have a different site of action
from those used in other crops in the rotation, it will be
more difficult for resistant populations to become established. Herbicides should also be rotated in a continuous monoculture system. Where two herbicide applications are made to a crop in the same year, avoid using
herbicides with the same site of action in both applications. Be sure to understand the components of premix
herbicides when planning herbicide programs.
Timely postemergence practices - In general,
triazine-resistant weed populations appear to develop
more rapidly in no-till cropping systems. Timely cultivation and/or postemergence herbicide application are
possible control options for conventional tillage. No-till
growers have a number of postemergence herbicide options available for timely control of weed escapes. Control of escaped weeds is necessary to prevent reseeding and development of resistant weed populations.
When rotating herbicide site of action to minimize
resistance problems, it is essential to know the site(s) of
action for herbicide products. Site of action definitions
are as follows. - the group number refers to the Weed
Science Society of America approved codes for herbicide site of action, which also appear on some herbicide
labels.
Group 1. ACC-ase Inhibitors (ACC). The ACC‑ase
inhibitors block the activity of an enzyme (Acetyl‑CoA
Carboxylase) involved in fatty acid biosynthesis. Group 1
herbicides are applied postemergence, and translocate
within the plant.
Group 2. ALS Inhibitors (ALS). ALS (acetolactate
synthase) is an enzyme involved in the synthesis of
several amino acids. This enzyme is also referred to as
acetohydroxy acid synthase (AHAS). Group 2 herbicides
are applied preemergence and postemergence, and
translocate within the plant.
Group 3. Microtubule Assembly Inhibitors (MAI).
The dinitroanilines and other herbicides in this class
interfere with the organization of microtubules. They
prevent polymerization of the protein tubulin into micro-
15
tubules. Microtubules are involved in cell division and
cell wall structure. Preemergence activity only. Uptake
by roots only, not translocated.
Group 4. Synthetic Auxins (SA). The synthetic
auxins interfere with plant growth by disrupting hormone
balance and protein synthesis. The exact site of action is unclear, and it is believed these herbicides have
several sites of action. Applied preemergence and
postemergence, but have primarily foliar activity. Group
4 herbicides translocate within the plant.
Group 5. Photosynthesis Inhibitors Binding Site A
(PS2 - A). Several classes of herbicides disrupt photosynthesis by blocking electron transfer in Photosystem
II (PSII). Herbicides in Classes PS2-A, PS2-B, and PS2-C
bind to the same protein in PSII, but the herbicides
exhibit different binding characteristics. For example,
resistance to the triazine herbicides usually is due to
a modification of the binding site. This modification
usually provides resistance to herbicides in class PS2A, but not for herbicides in classes PS2-B and PS2-C.
Because of this, Basagran and Buctril will control triazine
resistant weeds, even though the binding site for these
herbicides has been modified. Applied preemergence
and postemergence, but no translocation when applied
postemergence.
Group 6. Photosynthesis Inhibitors Binding Site A
(PS2 - B). See Photosynthesis Inhibitors Binding Site A.
Group 7. Photosynthesis Inhibitors Binding Site A
(PS2 - C). See Photosynthesis Inhibitors Binding Site A.
Group 8. Lipid Synthesis Inhibitors (LSI). The
thiocarbamate herbicides inhibit lipid synthesis, but the
exact site and site of action is unclear. These herbicides
may have multiple sites of action. Premergence activity
only.
Group 9. EPSP Inhibitors (EPSP). Glyphosate inhibits EPSP synthase (5‑enolpyruvyl‑shikimate‑3 phosphate
synthase), an enzyme involved in the production of
several amino acids. Both ALS-inhibiting and EPSP-inhibiting herbicides inhibit amino acid synthesis, but their
target sites affect different enzymes and they disrupt the
synthesis of different amino acids. Foliar activity only,
translocate within the plant.
Group 10. Glutamate Synthetase Inhibitors (GSI).
Glufosinate inhibits glutamine synthetase, a key enzyme
in incorporating ammonium into amino acids. Blockage
of this enzyme allows a buildup of phytotoxic ammonia.
Foliar activity only, not translocated.
Group 13. Carotenoid Biosynthesis Inhibitors (CBI).
Clomazone inhibits the synthesis of carotenoids by
possibly inhibiting production of all diterpenes, although
the exact target site is unknown. A lack of diterpenes
results in the loss of carotenoids and other compounds.
A primary role of carotenoids is to protect chlorophyll
from photo-oxidation. These herbicides are known as
bleachers because sensitive plants turn white due to the
loss of chlorophyll. Applied preemergence.
Group 14. PPO Inhibitors (PPO). These herbicides
inhibit PPO (protoporphyrinogen oxidase). Inhibition of
this enzyme results in the accumulation of Proto IX, a
molecule that generates singlet oxygen. Singlet oxygen
is highly reactive and disrupts membranes, resulting in
rapid degeneration of plant tissues. Applied preemergence and postemergence, but not translocated (contact activity only).
Group 15. Cell Division Inhibitors (CDI). Herbicides
inhibit proper cell division. The exact site of action for
these herbicides is unknown, but they are believed to
inhibit synthesis of very-long-chain fatty acids (VLCFAs)
during cell division. There may be multiple sites of action. Applied preemergence.
Group 19. Auxin Transport Inhibitors (ATI). Herbicides inhibit the flow of natural and synthetic auxins,
which are necessary for proper plant growth. The
auxins become more concentrated in growing points,
causing abnormal growth similar to synthetic auxin
herbicides. Group 19. Applied postemergence, translocated within the plant.
Group 22. Photosytem I Inhibitors (PS1). These
herbicides intercept electrons moving through Photosystem I (PSI). These electrons are then passed on to
other compounds, resulting in the formation of hydrogen
peroxide, which disrupts cellular integrity. Foliar activity
only, not translocated (contact activity only).
Group 27. 4-HPPD Inhibitors (4-HPPD). Inhibit the
enzyme 4‑HPPD (4‑hydroxyphenyl‑pyruvate‑dioxygenase), an enzyme involved in the synthesis of carotenoids
(See Carotenoid Biosynthesis Inhibitors). Applied
preemergence and postemergence, translocated within
plant when applied postemergence.
Abbreviations in this guide
AMS =
ammonium sulfate
COC =
crop oil concentrate
MSO =
methylated seed oil
NIS
=
nonionic surfactant
HSOC =
high surfactant oil concentrate (specified as HSOB on some labels)
UAN =
urea ammonium nitrate solution (28%,
32%)
Burndown
16
Burndown Herbicide Programs for Corn and
Soybeans
In no-till corn and soybean fields, it is essential to
apply herbicides with foliar activity before crop emergence to control existing weeds. Depending upon the
herbicide approach used in the field for that year, herbicides used to control weeds at planting may include
glyphosate or Gramoxone Max, or it may be possible to
rely solely on PRE herbicides with foliar activity (atrazine, Lexar/Lumax, Canopy, etc) in combination with
2,4-D. The latter approach will be most suitable when
the field is only sparsely populated with small winter annual weeds, and herbicides are applied in late March or
early April. Use of herbicide combinations in burndown
treatments is justified in most no-till fields, due to the
variety of winter weeds that are present. Consider fall
herbicide treatments in fields that are heavily infested
with winter weeds, such as chickweed, dandelions, wild
carrot, and poison hemlock.
Glyphosate (Roundup, Touchdown, Cornerstone, etc)
Fields with quackgrass, Canada thistle, dandelion,
and other cool-season perennial weeds will almost
always require the use of glyphosate around the time
of planting. This treatment can reduce the population
of perennial weeds that reach an appropriate size by
the time of application, such as quackgrass. For other
perennials such as Canada thistle, the level of longterm control with glyphosate will be variable, since they
may be small at the time of application. Application of
glyphosate to small perennials often controls existing
foliage, but regrowth occurs later in the growing crop.
Cool-season perennials, legumes, and cool-season
grasses are more effectively controlled with glyphosate
the previous fall if crop rotation allows. Glyphosate
is also effective on most annual broadleaf and grass
weeds, although the addition of 2,4-D ester greatly
improves control of marestail (horseweed), atriplex, giant
ragweed, mustard species and some other key no-till
weeds. Activity of glyphosate on established dandelion
and some winter annuals can be extremely slow when
applied in the spring under cool conditions, and use of
fall application or alternative herbicides should be considered in fields where chickweed, purple deadnettle,
and dandelion have been problematic (see later section
on fall applications). Glyphosate is most effective when
applied alone or with 2,4-D, in spray volumes of 10 gpa
or less, and when AMS is included in the spray mix.
AMS helps maintain glyphosate efп»їfectiveness in hard
water, or when mixed with residual herbicides. Glyphosate activity can be reduced when mixed with certain
residual herbicides (metribuzin, for example), and when
applied using 28% nitrogen solution or a similar material
as the spray carrier. For this reason, glyphosate labels
often specify that these types of mixtures should be
used only for control of small annual weeds.
2,4-D ester (Weedone, Salvo, etc.)
In many no-till fields, vegetation up until early May
consists primarily of broadleaf weeds, and 2,4-D ester
is an economical and effective tool for control of these
weeds. 2,4-D ester is most often used in combination
with other herbicides to ensure that complete control of
emerged weeds is achieved. Weeds not well-controlled
by other herbicides that 2,4-D helps out on include
marestail, prickly lettuce, mustards, giant ragweed,
Pennsylvania smartweed, and dandelion. When applied too close to soybean or corn planting, 2,4-D can
potentially reduce crop stands and cause injury to new
seedlings. With regard to soybeans, restrictions are as
follows for most products: rates up to 0.5 lb ai/A must
be applied at least 7 days before planting; rates between 0.5 and 1 lb ai/A must be applied at least 30 days
before planting. Several 2,4-D ester products, including
Salvo, Weedone 650, and E-99, can be applied at a rate
of 1 lb ai/A up to 15 days before planting. With regard to
corn, some labels suggest that 2,4-D be applied at least
7 to 14 days before planting or 3 to 5 days after planting. Other labels allow application anytime after planting. The risk of corn injury seems to be primarily when
2,4-D is applied around the time of corn planting, and
application is followed by enough rain to move 2,4-D
into the soil where seeds are germinating. There is also
risk of injury when seed furrows fail to close completely
and rain washes herbicide into the seed furrow where
direct contact with seed is possible. Injury may be more
severe when 2,4-D is applied with chloroacetamide herbicides, especially to corn in the spike stage.
Liberty (glufosinate)
Liberty is a contact herbicide that can be applied
preplant in ni-till to control small. emerged weeds. It is
most effective when applied with metribuzin and 2,4-D
17
Saflufenacil (Sharpen, Verdict,
Optill)
Saflufencail is a contact herbicide with activity on
annual broadleaf weeds, and especially marestail.
Saflufenacil alone is not adequate on most weeds, so it
is always applied with other burndown herbicides. A mix
of glyphosate plus salflufenacil can be applied anytime
before crop emergence, so it can subsititute for 2,4-D
when time until planting is lacking. The higher saflufenacil rates have residual activity on broadleaf weeds
also, including marestail. Saflufenacil does not contribute to control of perennial or biennial weeds or legumes.
Saflufenacil should be applied with MSO in relatively
high spray volumes (at least 15 gpa), and spray volume
should be increased as weed density increases.
Paraquat (Gramoxone SL,
Parazone)
Use of paraquat in no-till systems has declined
greatly over the past decade due to reductions in the
price of glyphosate and the greater versatility of glyphosate across a range of weed life cycles (perennial, biennial, etc) and sizes. Paraquat is most effective on small
annual weeds, and when combined with photosynthetic
inhibitor-type residual herbicides (atrazine, metribuzin).
Mixing 2,4-D ester with paraquat also results in more
complete control of broadleaf weeds. Paraquat is
probably most useful when rapid dessication of weeds
is essential, in order to allow tillage or planting. For
example, a combination of paraquat plus atrazine or
metribuzin will result in more rapid death and dessication of chickweed or purple deadnettle, compared
to glyphosate, when applied in the spring under cool
conditions. Paraquat should not be used for control of
perennial or biennial weeds, legumes, or cool-season
grasses. Paraquat is most effective when applied with
2,4-D and COC in relatively high spray volumes (at least
15 gpa), and spray volume should be increased as weed
density increases.
Residual herbicides with foliar
activity (atrazine, Canopy, etc)
A number of residual herbicides also have foliar activity, and will control or help control small annual weeds.
Herbicides in this category include atrazine, Callisto,
Balance Flexx, Corvus, Verdict, metribuzin, Canopy/
Cloak, Gangster, Envive, Valor XLT, Sonic, Authority First,
and Hornet. These herbicides have activity primarily on
small weeds, and the spectrum of control varies by herbicide. All have activity on broadleaf weeds, but most
have little or no activity on emerged grasses. The most
effective strategy when using one of these herbicides,
in order to minimize the need for glyphosate or paraquat, is to apply prior to early April with 2,4-D ester. If
emerged grasses are present, consult the product label
to make sure it will provide adequate grass control, and
supplement the spray mix with glyphosate or paraquat
as needed. Mixtures of residual herbicides with 2,4-D
and/or paraquat should generally be applied with COC.
Mixtures with glyphosate should include only AMS and
possibly NIS, depending upon the glyphosate product
used.
Fall herbicide treatments for
winter annuals and dandelions
Fall herbicide treatments have become a fairly common practice for some no-till producers, who recognize
their value for managing certain tough winter weeds and
providing a weedfree seedbed in the spring. The most
effective treatments based on our research include:
Any crop
next spring
Glyphosate + 2,4-D
Autumn/Autumn Super + glyphosate or 2,4-D
Metribuzin + 2,4-D (excluding dandelions)
dicamba + 2,4-D
Soybeans
next spring
Canopy EX/Cloak EX/Fallout + 2,4-D
Canopy/Cloak DF + 2,4-D (excluding chickweed)
2,4-D + Basis/Harrow (rate limited in areas)
Corn next
spring
Simazine + 2,4-D
2,4-D + Basis/Harrow
For control of winter annual weeds, apply herbicide
anytime after early October. For the most effective
dandelion control, delay application until after a frost.
We have applied as late as early December for control
of winter annual weeds, but we generally recommend
Burndown
ester, although 2,4-D ester is not needed for control of
most anual weeds. This can be an effective alternative
to combinations of glyphosate and 2,4-D ester where
glyphosate-resistant marestail occurs, or when there is
not enough time between application and planting to
use 2,4-D ester. Liberty is most effective when applied
under relatively warm, sunny conditions. It should be
applied in a spray volume of at least 15 gpa, and this
should be increased to 20 to 40 psi in dense weed
canopies. Avoid use of nozzles that result in coarse
spray droplets.
Burndown
18
application when dandelions are still mostly green, or by
mid-November if possible. Apply glyphosate-containing
treatments with AMS, and additional NIS if specified
by the product label. Treatments that do not contain
glyphosate should generally be applied with COC for
best results.
The treatments listed should cost producers no more
than about $8 to $15 per acre, excluding application
costs. It is not necessary to use more expensive treatments, and we really question the value of treatments
where the cost of the herbicide is more than about $12
per acre. One of the reasons for this is that the use of
a fall treatment, even one with residual activity, does
not guarantee that only one herbicide treatment will be
required in Roundup Ready soybeans the following year.
Excess money spent on fall treatments results in less
money available for weed control in the crop, where it
usually is greatly needed.
Our experience has been that the primary benefit of
fall treatments is control of weeds that are present at
the time of treatment, not residual control of weeds that
emerge the following year. The primary exception to this
is chlorimuron (Canopy/Cloak), which provides a longer
period of residual control of more weed species than
other fall-applied herbicides. An effective fall treatment
usually results in a field that is mostly free of weeds until
about late April, and this goes for treatments without
residual as well as those with residual. In other words,
in late April we cannot usually discern much difference
between a fall treatment of glyphosate plus 2,4-D versus
chlorimuron plus 2,4-D, even though the chlorimuron
provides residual activity into the spring. However, the
effect of the residual herbicide becomes much more
apparent by the end of May, when its activity on summer
annual weeds comes into play.
The issue here is not really control at the time of soybean planting, since any effective fall treatment results
in a relatively weed-free field at the end of April. The
issue is how well the residual herbicide controls weeds
after planting, in order to build more flexibility into the
postemergence application window. This flexibility can
result in less risk of early-season yield loss from weed
interference and result in a better chance of getting
the postemergence herbicides applied to the right size
weeds. We also look to the residual herbicide to help
control several weeds that glyphosate can be somewhat
variable on, such as giant ragweed and lambsquarters.
It is our opinion that, if glyphosate is being managed
properly, it is typically going to be extremely difficult to
get by with one postemergence glyphosate application
unless the residual herbicide applied in the fall provides
substantial weed control into late May.
Herbicides other than chlorimuron can provide residual control of certain weeds when applied in the fall,
but they tend to control fewer weed species and/or be
generally less effective than chlorimuron. For example,
Valor provides residual control of lambsquarters into
early June, but is less effective than Canopy EX and
provides very little control of giant ragweed. Scepter
provides very little control of lambsquarters or giant
ragweed when applied in the fall, whereas it can provide
substantial residual control of these weeds when applied in the spring.
19
Table 1. Weed Response to “Burndown” Herbicides
Deadnettle, henbit
Carolina Foxtail
Dandelion
9
9
9
9
9
9
9
8
-/7
7
9
8+
9
9
8
8
9
8
9
8+
9
9
9
9
8
7
8
6/7 9/9
7 9
8 9
8 9
9 9
9 9
7 9
8 9
8 9
7 9
7 9
7 9
8
9
9
9
9
9
9
7
8
9
6
-
6
8
6
6
6
6
6
6
6
6
6
6
6
6
8
9
8
8
9
9
9
9
9
9
8
8
8
8
9
9
9
-/7
9
9
9
9
9
9
8
7
9
9
9
9
9
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
6/7 7/8
8 9
6 8
9
8
8+ 8
8+ 9
8+ 9
8 9
7
7 7
8 9
6 7
8+ 8
8 8
8+ 8
8+ 9
6 9
8 8
8 8
Cressleaf groundsel
Annual Bluegrass
9
9
9
9
9
9
9
9
9
9
8
9
8
9
9
9
9
9
9
9
-/6 6/8 -/7 6/8 8/9 8/9
7 9 8 9 9 9
6
6 9 9
6 6
6 9 9
6
6 9 9
6
6 9 9
6 6
6 9 9
9 8 8 8
8
8 9 9 9 9 9
8 7 7 7 9 9
6 9 9
6 9 9
Prickly Lettuce
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8
8
-
Marestail (group 9-R)1
9
9
9
9
9
9
8
9
9
9
8
9
9
9
9
9
9
9
9
9
9
9
8
-
Hairy Vetch
NR
NR
7
9
7
9
9
9
9
NR
9
9
9
8
9
6
6
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
Alfalfa
Common chickweed
7
9
9
7
9
9
9
9
9
7+
9
Red Clover
Annual Smartweeds
-
Canada Thistle
Giant Ragweed
-
Orchardgrass/Fescue Sod
Common Ragweed
-
Winter Wheat, Rye Cover
Lambsquarters
-
Mustards, Shepherd's-purse
Giant Foxtail
-
Fall application
2,4-D (0.5 lb/1.0 lb)
2,4-D + dicamba
Autumn Super + glyphosate
Basis/Harrow + 2,4-D
Chlorimuron2 + 2,4-D
CanopyEX/CloakEX + 2,4-D
Tribenuron3 + 2,4-D (1.0 lb)
Glyphosate
Glyphosate + 2,4-D
Glyphosate + Sharpen
Metribuzin + 2,4-D
Simazine + 2,4-D
Spring application
2,4-D (0.5 lb/1.0 lb)
2,4-D + dicamba
Atrazine + 2,4-D
Atrazine + paraquat
Atrazine + Hornet/SureStart
Rimsulfuron4 + atrazine + 2,4-D
Chlorimuron2 + glyphosate
Chlorimuron2 + glyphosate + 2,4-D
Cloransulam2 + glyphosate + 2,4-D
Dicamba
Glyphosate
Glyphosate + 2,4-D
Glyphosate + Vida
Instigate + atrazine
Liberty/Cheetah + atrazine or metribuzin
Lumax/Lexar
Lumax/Lexar + 2,4-D
Metribuzin + paraquat + 2,4-D
Saflufenacil2 + glyphosate or Ignite
Saflufenacil2 + atrazine + glyphosate
1Ratings are for control of emerged marestail only.
7/8 - 8/9
9 6 9
9 8+ 9
9 9 9
9 8 8
9 9 9
9 7 8
9 7 9
9 7 9
9 6 7
7 7 8
8 7 9
7 7 8
9 9 8
9 9 9
9 9 8
9 9 9
9 9 9
9 8 9
9 9 9
7/8 7/8 8/9 7/8 8/9
9 8 9 9 9
8 7 8 9 9
7
8 9 9
6 6 7 8 9
7 7 8 9 9
7 6 6 8 8+
8 8 8 9 9
8 8 8 9 9
9 8 8 7 9
7 6 6
8
8 8 8 8+ 9
7 6 6
8
7 8 9
6 8+ 9
7 8 9
7 7 8 9 9
7 7 8 8+ 9
7 6 6 9 9
7 6 8 9 9
Marestail emerges in fall, spring, and early summer, and use of burndown plus residual herbicides in early spring results in
most effective control. See "horseweed (marestail)" in the "Problem Weed" section for more information.
2Chlorimuron products: Canopy/Cloak DF and EX, Valor XLT, Fierce XLT, Envive, and Authority XL/MAXX. Clorsansulam products: Authority First, Sonic, FirstRate, and Gangster. Saflufenacil products: Sharpen, Optill PRO, Verdict.
3Tribenuron products: Express, Panoflex, Nuance.
4Rimsulfuron products: Basis, Resolve, Harrow, Prequel, Crusher.
Burndown
This table gives a general comparative rating of “burndown” herbicides used in no-till corn and/or soybean production. Under
unfavorable conditions, some herbicides may not perform as well as indicated below. Under very favorable conditions, control may
be better than indicated. Herbicide rate, weed size and stage of growth, and environmental conditions interact to influence herbicide performance.
Weed control rating: 9 = 90% to 100%; 8 = 80% to 90%; 7 = 70% to 80%; 6 = 60% to 70% control; and - = less than 60% control,
not recommended.
Ratings are for control of existing vegetation only (not residual control). Treatments containing glyphosate should be applied with
AMS (and surfactant if required by the glyphosate product label). Most other treatments should be applied with a COC or MSO (plus
UAN if recommended by the label). Ratings for 2,4-D are based on a rate of 0.5 lb ai/A unless otherwise indicated - increasing the
2,4-D rate to 1.0 lb ai/A will improve control of legumes, dandelion, marestail, and some other weeds.
20
Burndown
Table 2. Application Intervals for Early Preplant Herbicides
This table gives the time interval, in days, that herbicides and herbicide combinations can be applied before planting corn or
soybeans. Herbicide rates may increase when applied early preplant; consult labels for detailed information on application rates.
Soil-applied herbicides not included in this table are not labeled for early application, and should be applied close to the time of
planting or as directed by the label. Fall applications are usually targeted for control of emerged winter annuals, biennials, and dandelion, and herbicides applied in fall usually provide only limited control of weeds that emerge the following spring.
Corn
Single Preplant Application in Spring
Labeled for Fall Application
Zidua, Anthem
up to 45 days
Yes
Acetochlor, acetochlor+atrazine, Anthem ATZ
up to 45 days
No
FulTime NXT
up to 40 days
No
up to 30 days
Yes
up to 30 days
No
Balance Flexx, Corvus, Prequel
up to 21 or 30 days2
No
Lumax, Lexar, Zemax, Instigate
up to 14 days
No
Metribuzin, simazine
up to 14 days
Yes
Valor, Fierce
7 to 30 days before planting
Yes
Soybeans
Single Preplant Application in spring
Labeled for Fall Application
anytime
Yes
anytime up to 1 or 7 days before planting
Yes
anytime, but no later than 3 days after planting
Yes
up to 45 days, no later than 3 days after planting
Yes
at least 7 to 14 days before planting3
Yes
Authority XL/MAXX
up to 60 days
Yes
Torment
up to 45 days
No
Canopy/Cloak DF, Scepter, pendimethalin, Zidua,
Anthem
up to 45 days
Yes
Optill PRO, Sharpen (residual use), Python
up to 30 days
Yes
Boundary/Tailwind/Ledger, Intimidator, Matador,
Pummel, metolachlor, Synchrony XP, Outlook1
up to 30 days
No
Metribuzin
up to 15 days
Yes
Prefix/Vise/Statement
up to 15 days
No
Gangster/Surveil
up to 14 days
Yes
up to 14 days before, no later than 3 days after plant
Yes
SureStart/TripleFLEX/TripleFLEX II, Python,
Sharpen, Verdict
Atrazine, Hornet, metolachlor,
metolachlor+atrazine, Expert, Outlook1
Sharpen (burndown use), Sonic
Afforia
Envive/Enlite, Trivence, Valor XLT, Fierce/Fierce XLT
Authority First/MTZ/Assist, Latir
Canopy EX/Cloak EX/Fallout3
Valor/Encompass/Outflank/Panther
1Early application of Outlook not recommended in areas where average annual rainfall exceeds 40 inches.
2Can be applied 30 days before planting if followed with planned postemergence treatments - otherwise it can be applied 21 days before planting.
3Canopy/Cloak EX rates of 2.2 oz or less should be applied at least 7 days before planting; rates of 2.2 to 3.3 oz should be applied at least 14 days before planting.
21
Burndown Herbicides in No-Tillage Corn and Soybeans
Herbicide
Formulation
Product Rate Range
Autumn Super
51 WDG
0.5 oz
в– в– Autumn Super (iodosulfuron-methyl and thiencarbazone) can be applied in fall before corn or soybeans planting, or
early spring at least 30 days before corn planting, for control of winter annual weeds and dandelion. Most effective
control occurs when mixed with glyphosate or 2,4-D and applied in the fall. Apply with 2,4-D for control of marestail
resistant to group 2 and/or 9.
в– в– Provides some residual control of winter annual grasses.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply with COC, MSO or oil blend (1% v/v) plus UAN (1.5 - 2 qts/A) or AMS (1.5 - 3 lbs/A).
в– в– Do not apply to frozen ground.
Herbicide
Formulation
Rimsulfuron + thifensulfuron (active ingredient)
Basis Blend
30DF
Resolve Q
22.4WDG
Crusher
50DF
Harrow
75DF
Product Rate Range
0.825 - 2 oz
1.25 - 2.5 oz
1 - 1.8 oz
0.33 - 1.0 oz
Burndown
Herbicide
Formulation
Product Rate Range
2,4-D Amine
Various
0.5 - 1 lb ai/A
2,4-D Ester Various
0.5 - 1 lb ai/A
в– в– Apply in fall or spring for control of emerged annual broadleaf weeds, including ragweeds, lambsquarters, mustard
species, marestail, prickly lettuce, and dandelion. Controls or suppresses perennial broadleaf weeds and legume
sods (alfalfa, clover).
в– в– Site of action: group 4 (see pages 14-15).
в– в– 2,4-D ester or amine can be applied preplant or preemergence to corn, but labels vary with regard to specific recommendations on timing of application. Labels for some products recommend application either 7 to 14 days before
planting or 3 to 5 days after planting before the corn has emerged, while others specify application any time after
planting.
в– в– Applications of 2,4-D around the time of planting can injure corn. This is more likely to occur in coarse-textured
soils with low organic matter content, and when above-average rainfall and prolonged soil moisture occur within
a week after planting. When applied preemeergence, 2,4-D amine is more likely to injure corn than 2,4-D ester.
Labels for some products do not allow preplant or preemergence use of 2,4-D on light, sandy soils. Injury may be
more severe when 2,4-D is applied with chloracetamide herbicides.
в– в– Many 2,4-D products are labeled for use in the spring prior to no-till soybean planting. OSU and Purdue University
recommend the use of only 2,4-D low-volatile ester (LVE) or similar products for this application. 2,4-D amine products are more water soluble and may leach into the seed zone. For 2,4-D LVE, rates up to 0.5 lb active ingredient
per acre must be applied at least 7 days before soybean planting. Application rates of more than 0.5 lb up to 1.0 lb
active ingredient per acre generally must be applied at least 30 days before planting. Several 2,4- ester products,
including E-99, Salvo, and Weedone 650, can be applied at a rate of 1.0 lb ai/A up to 15 days before planting. Do
not apply more than 1 lb ai per acre. Only one spring application is allowed per year.
в– в– 2,4-D is more effective than glyphosate for control of legume sods, marestail, dandelion, and prickly lettuce. For
best control of alfalfa prior to corn planting, apply in combination with 1/2 pint of dicamba. If legume sods are cut
prior to application of 2,4-D or 2,4-D plus dicamba, allow sufficient regrowth (4 to 6 inches) before herbicide application, or poor control may result.
в– в– When applied at rate of 1 lb ai/A in the fall, 2,4-D will control mustards, marestail, purple deadnettle, and many other
broadleaf weeds. Add glyphosate for effective control of common chickweed, wild carrot, poison hemlock, cressleaf groundsel, Canada thistle, dandelion, and grasses.
22
Burndown
Burndown Herbicides in No-Tillage Corn and Soybeans
Thifensulfuron + tribenuron (active ingredient)
Harmony Extra
50DF
0.75 - 0.9 oz
Nimble
75WDG
0.5 - 0.6 oz
Panoflex
50SG
0.3 - 0.6 oz
Tribenuron (active ingredient)
Express
50DF
0.25 - 0.5 oz
Nuance
75WDG
1/6 - 1/3 oz
в– в– Tribenuron products can be applied in the fall and/or spring before planting corn or soybeans for control of wild
garlic and other broadleaf weeds. When used in the spring, replant intervals for tribenuron products are generally
14 days between application and planting of corn and soybean. Thehe Panoflex label specifies 1 and 7 days until
soybean planting for rates up to 0.3 and 0.6 oz, respectively.
в– в– The premix of thifensulfuron and tribenuron-methyl controls wild garlic and annual broadleaf weeds, including
lambsquarters, mustard species, Pennsylvania smartweed, field pennycress, and shepherd's purse. Tribenuron
controls purple deadnettle, chickweed, and field pennycress, and provides partial control of shepherd's-purse and
other mustard species. Apply with 2,4-D ester for best results.
в– в– Premixes of rimsulfuron plus thifensulfuron can be applied in the fall or spring before planting corn for control of
winter annual weeds. When mixed with 2,4-D ester, these herbicides control chickweed, deadnettle, henbit, dandelion, mustards. and other winter weeds. Spring applications with other corn herbicides (2,4-D ester, atrazine) before
corn planting can provide burndown of small annual grass and broadleaf weeds, and several weeks of residual
control of foxtails, lambsquarters, and pigweeds. See labels for adjuvants recommednations. Can be mixed with
other herbicides approved for these uses.
в– в– The 0.825 oz rate of Basis Blend can be applied up to 15 days before soybean planting. South of I-70, Basis can be
applied at rates up to 1.25 oz/A in the fall prior to soybean planting. Crusher can be applied at rates up to 1 oz/A in
fall or early spring, at least 30 days before soybean planting.
в– в– Site of action: group 2 (see pages 14-15).
в– в– To control wild garlic, apply the higher rates of thifensulfuron+tribenuron when garlic plants are less than 12 inches
tall with 2 to 4 inches of new growth. Control will be better if applied during warm weather (60 F or more) to actively
growing garlic plants. Thorough spray coverage of garlic plants is essential.
в– в– All of these products should be applied with NIS or COC, and UAN or AMS can be added, See labels for specific
adjuvant recommendations. Use flat fan or low-volume flood nozzles for best results.
Herbicide
Formulation
Product Rate Range
Chlorimuron (active ingredient)
Canopy EX/Cloak EX/Fallout
29.5 DF
1.1 to 3.3 oz
Canopy/Cloak DF
75 DF
2.25 to 7 oz
Envive
41 DG
2.5 to 5 oz
Enlite
47.9 DG
2.8 to 4.235 oz
Valor XLT
40 WDG
2.5 to 5 oz
Fierce XLT
62.4 WDG
3.75 to 5.25 oz
Authority XL
70 DF
3 to 9.6 oz
Authority MAXX
66DF
6 to 9.6 oz
Trivence 61.3 WDG
6 to 10 oz
в– в– These products provide residual control of broadleaf weeds, and the chlorimuron component helps control many
emerged no-till weeds in mixtures with 2,4-D and glyphosate in preplant burndown treatments. See descriptions of
these herbicides in "Soybean: Soil-Applied Herbicides" section for more information.
в– в– Do not apply to frozen or snow-covered ground.
в– в– Maximum rate on soils where the composite pH exceeds 7.0 (pH 6.8 for Valor XLT/Fierce XLT): Canopy/Cloak EX -
23
Burndown Herbicides in No-Tillage Corn and Soybeans
в– в– в– в– в– в– Herbicide
Formulation
Product Rate Range
Dicamba
4L
1/2 - 1 pt
Distinct
76.4DF
2 - 3 oz
в– в– Dicamba is sold under a number of trade names, including Banvel, Clarity, Sterling Blue, and Oracle. Dicamba is a
translocated herbicide that can be applied before, during, or after no-till corn planting for control of emerged broadleaf weeds.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Use 1/2 pint on coarse-textured soils, and 1 pint on medium- or fine-textured soils containing at least 2 percent
organic matter.
в– в– Dicamba is more effective than glyphosate for control of legume sods, especially when applied in combination with
2,4-D. When planting into a legume sod, apply dicamba after regrowth of 4 to 6 inches has occurred.
в– в– The addition of crop oil, surfactant, or fluid fertilizer may improve control of emerged weeds. Do not apply with crop
oil when corn is more than 5 inches tall.
в– в– Corn should be planted at least 1ВЅ inches deep with good-seed furrow closure. May injure corn if recommended
rates are exceeded, application is not uniform, or corn is planted too shallow.
в– в– The 1 pint rate provides limited residual control of small-seeded, annual broadleaf weeds.
в– в– Some dicamba products are labeled for application in the spring prior to soybean planting, but there is more risk of
injury to soybeans compared with preplant application of 2,4-D ester. Labels specify at least 14 to 28 days between
application and soybean planting, and the waiting period starts after the accumulation of one inch of rain. For
example, the Clarity label states the following: following application of Clarity and a minimum accumulation of one
inch of rain, a waiting interval of 14 days until planting is required for rates of 8 oz/A or less, and 28 days for rates up
to 16 oz/A”.
в– в– Distinct is a premix of dicamba and diflufenzopyr, and is more active that dicamba on a number of weeds. Distinct
rates: corn - 2 to 3 oz/A applied at least 14 days before planting; soybeans - 2 to 4 oz/A, at least 30 days. Following
application, at least 1 inch of rain must occur before the 14 or 30-day waiting period starts.
Herbicide
Formulation
Product Rate Range
Dicamba + 2,4-D premix
3.87L
0.5 - 6 pts
в– в– This product is available from various manufacturers, and product names and rates vary. It controls emerged
weeds in the fall after corn or soybean harvest, or in the summer or fall after wheat harvest. Similar products are
available from other manufacturers.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Controls mustards, marestail, cressleaf groundsel, dandelion and some other winter annual weeds, but is weak on
purple deadnettle and common chickweed.
Burndown
в– в– 1.1 oz; Canopy/Cloak DF - 2.25 oz; Valor XLT and Envive - 2.5 oz; Fierce XLT - 3.75 oz; Trivence - 6 oz. Authority XL
cannot be applied on soils with pH greater than 7.6. Authority XL rates are not pH-dependent, but XL rotation intervals for most crops are extended to at least 18 months for soil pH between 7.2 and 7.6 regardless of rate. Authority
MAXX and Enlite rates and rotation intervals are not pH-dependent.
These products can be applied to no-till or conservation tillage fields in the fall for burndown of existing vegetation
and limited residual control into the following growing season. 2,4-D should be included with all fall-applied treatments. Do not apply to frozen ground.
Canopy/Cloak EX controls common chickweed, but the other products listed here require the addition of glyphosate or Express for chickweed control.
Spring treatments should include 2,4-D ester and/or glyphosate for most effective control of emerged weeds.
Glyphosate should be included if applied later than early April and where marestail, dandelion, and other perennials
are present.
Apply with COC (1 gallon/100 gallons spray) for best control of emerged weeds, unless glyphosate is included in the
treatment.
24
Burndown
Burndown Herbicides in No-Tillage Corn and Soybeans
в– в– Apply when annual weeds are less than 6 inches tall, when biennials are in the rosette stage, and when perennials
are at least 6 inches tall or in the bud to bloom stage.
в– в– Any crop can be planted 120 days after application of rates up to 6 pints per acre. For some products/rates, crops
may be planted sooner than 120 days, enabling preplant use in spring. See labels for more information.
в– в– Can be applied prior to wheat planting, but allow an additional 10 days between application and planting for each
pint applied (e.g. for a 2 pint rate allow 20 days).
в– в– The standard adjuvant recommendation is 2 to 4 pints of NIS per 100 gallons of spray solution.
Herbicide
Formulation
Product Rate Range
Dicamba + atrazine premix
3.2L
2 - 3 1/2 pt
в– в– Dicamba plus atrazine is sold under a number of trade names, including Marksman, Sterling Plus, BanvelK+atrazine, and Stratos. These products control most emerged annual broadleaf weeds, and suppress or control
perennial broadleaf weeds, and provide some residual control of broadleaf weeds.
в– в– Site of action: group 5 (atrazine), group 4 (dicamba). See pages 14-15.
в– в– Can be applied before, during, or after planting to emerged, actively growing weeds. Apply 2 pints on coarse soils
with at least 2 percent organic matter, and 3ВЅ pints on medium- or fine-textured soils with at least 2 percent organic
matter.
в– в– The addition of crop oil, surfactant, or fluid fertilizer may improve control of emerged weeds. Do not apply with crop
oil after corn is 5 inches tall.
в– в– When planting into a legume sod, apply after regrowth of 4 to 6 inches has occurred.
в– в– Corn should be planted at least 1ВЅ inches deep with good seed-furrow closure. May injure corn if recommended
rates are exceeded, application is not uniform, or corn is planted too shallow.
Herbicide
Formulation
Expert4.88L
в– в– Expert is a premix of glyphosate, s-metolachlor (Dual II Magnum), and atrazine for burndown and residual control of grass and broadleaf weeds in no-till and conservation tillage corn. See descriptions of glyphosate and
metolachlor/s-metolachlor plus atrazine for more information on these herbicides.
в– в– Site of action: group 9 (glyphosate), group 5 (atrazine), group 15 (s-metolachlor). See pages 14-15.
в– в– Use rates provide the equivalent of 0.4 to 0.75 lbs of glyphosate acid and 1.75 to 2.6 quarts/A of Bicep II Magnum.
Use rate ranges from 2.5 to 3.75 qts/A on coarse-textured soils with less than 3% organic matter, and from 3 to 3.75
on all other soils.
в– в– Apply before, during, or after planting but before crop emergence.
в– в– Can be applied postemergence to glyphosate-resistant corn. Use water as the spray carrier for postemergence
applications.
в– в– Can be applied in water or UAN (28% or 32% only). Control of emerged weeds, especially perennial and large annual weeds, may be reduced if fertilizer is used as the carrier.
в– в– The addition of AMS (17 lbs/100 gallons) can improve control of emerged annual weeds under cool or dry conditions.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
0.75 - 1.5 lbs acid/A
в– в– Do not apply broadcast after the crop has emerged, unless the crop has resistance to glyphosate (Roundup Ready,
Agrisure GT, etc).
в– в– To reduce the risk of developing glyphosate-resistant weed populations, OSU and Purdue University recommend
application of glyphosate with 2,4-D ester wherever practical, including preplant applications to no-till corn and
soybeans, in the summer/fall following wheat harvest, and in the fall for control of winter annuals and dandelion. An
exception to this occurs when Canada thistle is the primary weed target for a fall application, in which case the 2,4D ester should be omitted.
25
Burndown Herbicides in No-Tillage Corn and Soybeans
Herbicide
Formulation
Product Rate Range
Gramoxone SL
2L
2 - 4 pts
Parazone
3SL
1.3 - 2.7 pts
в– в– Do not apply broadcast after the crop has emerged.
в– в– Gramoxone SL and Parazone contain paraquat, a nonselective contact herbicide that controls emerged annual
grass and broadleaf weeds. Paraquat usually provides acceptable control of a rye cover, but is less effective than
glyphosate for control of forage grasses such as orchardgrass and tall fescue. Paraquat is not effective for control
of perennial broadleaf weeds, legume sods, perennial grass sods, or volunteer wheat although some suppression
of these may occur.
в– в– Site of action: group 22 (see pages 14-15).
в– в– May not control marestail and prickly lettuce. May not control smartweed, giant ragweed, and fall panicum that are
more than 4 to 6 inches tall. Control of these and many other weeds will be improved when paraquat is mixed with
Burndown
в– в– Glyphosate is a nonselective, translocated herbicide that controls emerged annual and perennial grass and broadleaf weeds, volunteer cereals, and grass cover crops. Table 24 contains a list of some currently available glyphosate products. Application rates, adjuvant recommendations, and other guidelines for use vary among glyphosate
products, and users should consult labels and local product use guides for more specific information. The following
comments are meant as general guidelines for the use of glyphosate.
в– в– Site of action: group 9 (see pages 14-15).
в– в– The minimum glyphosate rate for most situations where weeds are no more than about 6 inches tall should be 0.75
lbs of glyphosate acid/A. Rates should be increased accordingly as weeds become taller. Pennsylvania smartweed, atriplex, giant ragweed, crabgrass, fall panicum, barnyardgrass, marestail, dandelion, and a number of winter
annual weeds can be difficult to control, and should be as small as possible at the time of application. A mixture of
glyphosate plus 2,4-D ester (0.5-1 lb ai/A) will improve control of most broadleaf weeds.
в– в– Glyphosate resistance has developed in populations of marestail, waterhemp, and Palmer amaranth, and common
and giant ragweed in Ohio, Indiana, and Illinois, and some lambsquarters populations appear to have become less
sensitive to glyphosate. To improve control of these populations and reduce the risk of resistance, apply a mixture
of glyphosate plus 2,4-D ester at least 7 days before soybean planting, and include preemergence herbicides that
have residual activity on these weeds (e.g. Valor, metribuzin, Gangster). Avoid use of herbicide programs in glyphosate-resistant crops consisting solely of multiple glyphosate applications. See the “Problem Weeds” section of this
guide for additional information on management of these weeds.
в– в– For control of rye or overwintered wheat, apply in a spray volume of 10 gpa or less and use the appropriate rate for
small grain size. Wheat should be treated before reaching a height of 18 inches.
в– в– A number of glyphosate products can be applied immediately prior to alfalfa harvest in spring or fall, and the treated alfalfa then harvested and fed to livestock. This application is useful where corn will be planted immediately after alfalfa harvest, since it provides more effective alfalfa and perennial grass control, compared to application after
harvest. Allow a minimum of 36 hours between application and harvest. Alfalfa should be harvested 3 to 7 days
after application to avoid loss of quality and maximize perennial control. The preemergence herbicide program for
corn should include atrazine at a rate of 1Вј to 1ВЅ quarts (or the equivalent amount in a premix).
в– в– Glyphosate activity will be maximized when applied in water in a spray volume of 10 gpa or less. When mixing with
residual herbicides, apply in 10 or more gallons of water or UAN per acre.
в– в– Glyphosate activity on perennial and large annual weeds may be reduced when mixing with residual herbicides
or applying in UAN. Residual herbicides with contact activity on emerged weeds (Valor, metribuzin, atrazine, etc)
are most likely to reduce glyphosate activity. Consult labels for rates and precautions when mixing with residual
herbicides.
в– в– Recommendations for the use of AMS (17 lbs/100 gallons of water) with glyphosate vary among products. Addition
of AMS may improve control, and is recommended under the following conditions: when mixing with residual corn
or soybean herbicides, when air temperature is 55 degrees or less, or when hard or high pH water is used as the
carrier.
26
Burndown
Burndown Herbicides in No-Tillage Corn and Soybeans
в– в– в– в– в– в– в– в– в– в– photosynthetic inhibitor herbicides (atrazine, metribuzin, and Lorox). Paraquat should generally be applied with a
metribuzin-containing product and 2,4-D ester in no-till soybeans.
Application rates for Gramoxone SL: 2 to 2.5 pints for 1- to 3-inch weeds; 2.5 to 3 pints for 3- to 6-inch weeds; and 3
to 4 pints for weeds more than 6 inches tall. Application rates for Parazone: 1.3 to 1.7 pints for 1- to 3-inch weeds; 1.7
to 2 pints for 3- to 6-inch weeds; and 2 to 2.7 pints for weeds more than 6 inches tall
Apply with COC (1 gallon/100 gallons spray) or NIS (1 quart/100 gallons). COC is the preferred spray adjuvant, especially when mixing with other herbicides.
When using flat fan nozzles spaced at 20 inches or less, apply in a spray volume of at least 10 gpa with a pressure
of at least 30 psi. Increase spray volume to at least 15 to 20 gpa if weeds are more than 3 inches tall. For large
spray equipment with flood type nozzles, use a spray volume of at least 20 gpa with a pressure of at least 30 psi.
Allow 30 minutes between application and rainfall.
Do not apply with suspension or high-phosphate liquid fertilizers.
Herbicide
Formulation
Product Rate Range
Liberty 280 SL/Cheetah
2.34L
29 - 36 oz
в– в– Liberty/Cheetah (glufosinate) is a contact herbicide that controls small, annual grass and broadleaf weeds, and suppresses some perennials.
в– в– Site of action: group 10 (see pages 14-15).
в– в– Application of glufosinate alone controls marestail and ragweeds, but may not provide adequate control of all of
the weeds that can found in a typical no-till burndown situation. Apply in combination with 2,4-D ester and/or a
metribuzin-containing herbicide (at least 0.2 lb ai metribuzin) for most effective control, or with Sharpen, especially
where the field was not treated the previous fall.
в– в– Maximum amount of Liberty that can be applied per season (burndown + POST) in LibertyLink crops: corn - 44 oz;
soybeans - 65 oz. See Cheetah label for information on maximum amount per season.
в– в– Apply in a minimum spray volume of 15 gpa, and use 20 to 40 gpa in dense weed canopies. Apply using nozzles
and spray pressures that result in medium-size spray droplets (250 to 350 microns). Control can be reduced when
nozzles and pressure result in coarse droplets.
в– в– Control can be reduced when applied to weeds under stress from drought or cold conditions.
Herbicide
Formulation
Lumax4L
Lexar3.7L
в– в– Lumax and Lexar are premixes of atrazine plus s-metolachlor (Dual II Magnum) plus mesotrione (Callisto). A use rate
of Lexar contains a higher amount of atrazine per acre, compared with Lumax, and a lower amount of s-metolachlor.
в– в– Site of action: group 5 (atrazine); group 15 (s-metolachlor); group 27 (mesotrione). See pages 14-15.
в– в– Lexar and Lumax have been among the most effective preplant burndown treatments for no-till corn in OSU and
Purdue University research, for control of dandelion and most winter annual weeds. These products also provide
residual control of annual grass and broadleaf weeds. See descriptions of these products in the corn herbicide section for more information.
в– в– Lexar use rates: soils with less than 3% organic matter - 3 qts/A; soils with more than 3% organic matter - 3.5 qts/A.
Lumax use rates: soils with less than 3% organic matter - 2.5 qts/A; soils with more than 3% organic matter - 3.0
qts/A.
■■See descriptions of these products in “Corn: Soil-Applied Herbicides” section for additional information.
Herbicide
Formulation
Product Rate
Prequel
45WDG
1.66 to 2.5 oz
в– в– Prequel is premix of isoxaflutole (Balance Pro) and rimsulfuron that provides residual control of grass and broadleaf
weeds, and also controls some small (less than 3 inches), emerged weeds in no-till burndown situations. See Prequel description in “Corn: Soil-applied Herbicides” section for more information.
27
Burndown Herbicides in No-Tillage Corn and Soybeans
Herbicide
Formulation
Product Rate
Sharpen (corn)
2.85SC
2 to 3.5 oz
Sharpen (soybeans)
1 to 2 oz
Sharpen (wheat)
1 to 2 oz
Optill PRO (soybeans)
co-pack
Verdict (corn)
5.57 EC
10 to 18 oz
Verdict (soybeans)
5 to 10 oz
в– в– These products contain saflufenacil, which can help control emerged weeds, especially marestail, in preplant no-till
burndown treatments. When used in soybeans, saflufenacil products should be combined with glyphosate or Liberty for broad-spectrum burndown. The combination of Verdict/Sharpen and atrazine may provide adequate burndown of small weeds in no-till corn, but glyphosate should be added when weeds are more than about 4 inches
tall, and for weeds Verdict/Sharpen does not control (see label). For more information on these products, see their
descriptions in “Soybeans: Soil-applied Herbicides” and “Corn: Soil-applied Herbicides.”
в– в– Can be applied in the fall prior to soybeans. The lower rates for soybeans can be applied anytime prior to crop
emergence, unless mixed with products that contain flumioxazin, sulfentrazone, or fomesafen. The higher rates
must be applied 14 to 44 days before planting depending upon rate and soil type. See rate tables for these products in the “Soybeans: Soil-applied Herbicides” section for detailed information.
в– в– Burndown activity requires the addition of MSO (1% v/v) plus either AMS (8.5 to 17 lbs/100 gallons) or UAN (1.25 to
2.5% v/v). Use a spray volume of 15 to 20 gpa in fall/spring no-till burndown situations, or where emerged weeds
are present. Flat fan nozzles are recommended for burndown applications.
в– в– Salfufenacil products used in soybeans cannot be mixed with or applied within 30 days of products containing
flumioxazin (Valor products, Envive, Gangster, etc), sulfentrazone (Sonic, Authority products), or fomesafen (Prefix,
Intimidator, etc), with the following exception: Sharpen can be applied 14 days before planting when mixed with
these herbicides except on coarse-textured soils with less than 2% organic matter.
Herbicide
Formulation
Product Rate Range
Vida
0.208L
1 - 2 oz
в– в– Vida (pyraflufen ethyl) is a contact herbicide with limited activity on primarily small annual broadleaf weeds, for use
in mixtures with other effective burndown herbicides. The addition of this product to other herbicides may result in
more rapid development of symptoms on weeds but has not generally improved overall control.
в– в– Site of action: group 14 (see pages 14-15).
в– в– If using a water source with pH greater than 5.0, add an approved agricultural bufferung agent to reduce pH to 5.0
or less.
Burndown
в– в– Control of emerged weeds can be improved with the addition of one or more of the following: 2,4-D, atrazine,
glyphosate, or paraquat. Control of emerged weeds requires the addition of NIS or COC plus AMS or UAN. When
mixed with Liberty or a glyphosate product that contains adjuvants, no additional NIS or COC is needed.
■■See description of this product in “Corn: Soil-Applied Herbicides” section for additional information.
28
Corn
Corn Herbicide Management Strategies
Preemergence herbicide programs have long been
the mainstay of weed management in corn, due in large
part to the low cost of atrazine and its broad spectrum
of control. A total preemergence approach can still be
effective in fields with low to moderate populations of
most annual weeds. The commonly used premix of
atrazine plus an acetamide herbicide (Bicep II Magnum,
Degree Xtra, Keystone, etc) can be supplemented as
necessary with Balance, Python, Callisto (Lexar, Lumax), Hornet, or simazine to improve control of weeds
such as fall panicum, triazine-resistant lambsquarters,
giant ragweed, and velvetleaf. In fields with moderate to high weed populations, a preemergence plus
postemergence approach will provide more consistent
control with less risk of corn injury. A number of options
are available for this type of program at a reasonable
cost. A preemergence plus postemergence approach
is especially effective in fields with giant ragweed,
burcucumber, moderate to high annual populations of
annual grasses and triazine-resistant lambsquarters, and
perennial weeds. A number of effective total postemergence herbicide programs are also available. However,
research indicates that total postemergence programs
lacking residual activity should be used only in fields
with low weed populations. A total postemergence herbicide program should be applied before most weeds in
a field exceed 2 to 4 inches in height, and reinfestation
with later-emerging weeds is likely if a herbicide with
residual activity is not included.
Preemergence Corn Herbicide
Programs
Total preemergence (PRE) herbicide programs fit
fields with:
в– в– low to moderate annual grass populations
в– в– low giant ragweed populations
в– в– any level of population of most annual broadleaf
weeds
Total preemergence programs do not fit fields with:
в– в– high grass populations
в– в– moderate to high giant ragweed, cocklebur, velvetleaf, and annual morningglory populations
в– в– perennial weeds
в– в– waterhemp, Palmer amaranth, and burcucumber
Advantages of PRE programs:
в– в– one-pass, can apply while planting
в– в– with adequate rain, provides control through the first
6 weeks, and later-emerging weeds have little impact
on corn yield
в– в– effective on many annual grass and broadleaf weeds
Disadvantages of PRE programs:
в– в– dependence upon adequate rain within narrow period of time
в– в– not effective enough on tough broadleaf or perennial
weeds or in high grass populations
в– в– corn needs to be competitive with weeds earlier in
season compared to PRE plus POST programs
Approaches:
Atrazine premix products (Lexar, Harness Xtra, etc) or
similar mixes are effective broad-spectrum treatments
for fields suited to total preemergence.
в– в– can add simazine or Balance Flexx to improve grass
control (or use a mixture of Radius + atrazine)
в– в– can add Balance Flexx to improve consistency under
low rainfall conditions
в– в– can add Balance Flexx, Callisto, Python, or Hornet
to improve triazine-resistant lambsquarters, giant
ragweed, and velvetleaf control, or apply premix
products that contain these herbicides.
в– в– atrazine rates of 1.5 to 2 lb/A can improve control of
velvetleaf and giant ragweed. Some premix products
have less than 1.5 lbs/A
Preemergence plus Postemergence Corn Herbicide Programs
Preemergence (PRE) plus Postemergence (POST)
herbicide programs fit any field, but are especially
well-suited for fields with:
в– в– moderate to high annual grass populations
в– в– moderate to high giant ragweed, cocklebur, velvetleaf, and annual morningglory populations
в– в– perennial weeds
в– в– waterhemp, Palmer amaranth, and burcucumber
Advantages of PRE plus POST programs:
в– в– very consistent, as long as some rain on PRE
в– в– creates wider window for POST application, compared to total POST programs
29
Disadvantages of total POST with residual:
Disdvantages of PRE plus POST programs:
в– в– should be applied before weeds exceed 2 to 4
inches in height to avoid yield loss
в– в– application too early for best perennial weed control
в– в– need rain within 2 weeks of application for residual
activity
в– в– dependence upon rain for PRE activity (although
have planned POST backup)
в– в– two-pass
в– в– cost
Approaches:
In fields with low to moderate grass populations, can
take an approach of preemergence grass herbicide followed by postemergence broadleaf herbicide (without
much grass activity). Examples:
в– в– Outlook followed by dicamba + atrazine
в– в– Surpass followed by Hornet + Clarity
To provide postemergence control of a few grass escapes, can take an approach of a preemergence grass
or grass and broadleaf herbicide followed by a postemergence broadleaf herbicide that also has activity on
small grasses. Examples:
в– в– Dual II Magnum followed by NorthStar
в– в– Outlook followed by Status + atrazine
In fields with moderate to high grass and/or problem broadleaf populations, can take an approach of
preemergence grass or grass+broadleaf herbicide (full
or reduced rate) followed by broad-spectrum postemergence herbicide with grass and broadleaf activity.
Examples:
в– в– Corvus followed by Liberty (Liberty Link corn)
в– в– Harness Xtra followed by glyphosate (RR corn)
Total Postemergence Corn Herbicide Programs (with residual)
Total postemergence (POST) herbicide programs
that provide substantial residual control can be
used in fields with:
в– в– most annual weed populations
Avoid use in fields with:
в– в– perennial broadleaf weeds (might emerge too late for
control)
в– в– high giant ragweed and annual grass populations
Advantages of total POST with residual:
в– в– one-pass, can plant first and apply later
в– в– not dependent upon rainfall for postemergence
activity (although soil moisture status affects weed
response to herbicides)
в– в– consistent control of many annual weed populations
Approaches:
Can make a single postemergence application
before weeds exceed 4 inches in height with mix of postemergence herbicides with grass and broadleaf activity
and residual herbicides with primarily broadleaf activity
(if grass population not high). Examples:
в– в– Liberty + atrazine (Liberty Link corn)
в– в– glyphosate plus atrazine (glyphosate-resistant corn)
In fields with moderate to high grass pressure, may
need residual component with more activity on grasses
than those listed above. Examples:
в– в– Glyphosate + Degree Xtra (glyphosate-resistant corn)
в– в– Halex GT (glyphosate-resistant corn)
в– в– Liberty + atrazine/chloroacetamide premix (Liberty
Link corn)
Corn
в– в– good on many tough weeds
30
Weed control rating: Crop tolerance rating:
9 = 90% to 100% control
0 = Excellent
8 = 80% to 90% control
1 = Good
7 = 70% to 80% control
2 = Fair
6 = 60% to 70% control
3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
8
8
8
Yellow Nutsedge
2
2
Woolly cupgrass
7
3
Quackgrass
8
8
8
8
7
8+
8
6
8+
8+
8
8
8
6
7
8
8
8+
8
Rhizome Johnsongrass
9
9
8
8
7
6
8+
8
6
9
9
9
8+
7
6
7
8
8
9
8
Shattercane
Fall Panicum
9
9
8
8
8
7
8
8
7
9
8
9
8
8
7
8
8
8
8
8
Yellow Foxtail
Crabgrass
1
1
1
1
0
1
1
1
1
2
1
1
1
1
1
2
2
1
1
0
2
1
1
1
1
Giant Foxtail
Barnyardgrass
15
5/15
15
5/15
5
27
27
2/27
14/15
2/4
2/28
5/27/15
15
5/15
15
2/27
2
2
14
5
2/4/15
14
14/15
15/27
15
Field Sandbur
Crop Tolerance
Grasses
Site of Action
Corn
Table 3. Weed Response to Preplant/Preemergence Herbicides in Corn—Grasses
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for additional information on site of action classification.
7
7
6
6
6
6
6
6
6
6
6
6
6
6
6
6
9
9
9
9
7
7
8+
8
7
9
9
9
8+
8
7
8
8
8
9
9
9
9
8
8
7
6
8+
8
7
9
9
9
8+
7
7
8
8
8
9
8
6
7
6
-
6
7
6
-
6
6
8
6
6
6
-
7+
7+
6
6
8
7
6
6
7
7
7
7
6
6
7
7
6
8+
8+
6
7
7
8
8+
8
8
7
8+
-
8
8
6
6
-
8
-
Preplant or Preemergence
Acetochlor1
Acetochlor+atrazine1
Anthem
Anthem ATZ
Atrazine
Balance Flexx
Callisto
Corvus
Fierce2,3
Hornet
Instigate
Lumax/Lexar EZ
Metolachlor1
Metolachlor + atrazine1
Outlook
Prequel2
Python
Resolve Q/Crusher
Sharpen2
Simazine
SureStart/TripleFlex2
Valor3
Verdict2
Zemax
Zidua
Preemergence
Lorox/Linex
Pendimethalin
7
1Acetochlor, alachlor, metolachlor, and s-metolachlor, and premixes of these with atrazine are available from a number of manufacturers - see corn herbicide descriptions for
more information. Broadleaf weed control ratings assume an atrazine rate of 1.5 lbs ai/A - the atrazine rate in some premix products may be lower.
2SureStart/TripleFlex, Verdict, Sharpen, Fierce, and Prequel are intended for use in planned preemergence followed by postemergence programs, and ratings indicate earlyseason effectiveness, not full-season control. PRE application of these products should be followed with a POST application of Liberty, glyphosate, or other herbicides as
necessary.
3Valor and Fierce must be applied at least 7 days before corn planting. Use only in no-till fields.
31
Table 4. Weed Response to Preplant/Preemergence Herbicides in Corn—Broadleaf Weeds
Weed control rating: Crop tolerance rating:
9 = 90% to 100% control
0 = Excellent
8 = 80% to 90% control
1 = Good
7 = 70% to 80% control
2 = Fair
6 = 60% to 70% control
3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
Annual Morningglory
Black Nightshade
Burcucumber
Cocklebur
Common Ragweed
Common ragweed (group 2-R)
Giant Ragweed
Giant ragweed (group 2-R)
Jimsonweed
Kochia
Lambsquarters
Lambsquarters (group 5-R)
Palmer amaranth (group 2-R)
Pigweed (redroot/smooth)
Smartweed
Velvetleaf
Waterhemp (group 2-R)
Broadleaf Weeds
8
7
8
6
7
6
6
8
8
7
7
8
7
6
7
8
6
-
8+
9
8
9
9
9
9
9
9
8+
9
9
8
9
8+
8
8
8
9
8+
9
9
9
8
6
6
6
7
7
7
7
7
6
7
?
6
7
-
8
7
8
7
8
7
8
8
7
8
7
8
8
7
-
7
9
7
9
9
9
7
9
8
8+
8
9
9
8
7
7
8
9
8+
7
9
7
7
7
9
7
9
9
9
7
9
8
8+
7
9
9
8
8
9
8+
7
9
7
7
8
6
8
6
6
6
7+
6
8
8
6
8
7
7+
8
6
-
8
6
8
6
6
6
7+
6
8
8
6
8
7
7+
8
6
-
9
7
9
9
9
8
9
9
8
7
7
8
8
8
8
-
9
7+
9
9
9
6
9
7
8
7
9
9
9
7
8
8
9
7
8
8
7+
7+
9
8
9
9
9
9
9
9
9
9
9
6
9
6
9
9
7
9
9
9
9
9
9
8
7+
7+
8
8
9
9
9
9
9
9
9
6
6
6
9
9
7
9
9
9
9
9
8
8
9
8
8+
8
8
7
8
8
7
9
7
8+
7+
8
8
8
7
8
9
8
8
8+
9
8
9
9
9
9
9
9
9
9
9
8
9
8
9
9
7
9
9
9
9
9
9
8
9
9
9
8
9
8
7
8+
9
9
9
8
8
7
8
8+
8+
7
9
9
-
8
7
8
8
9
9
9
7
9
9
9
8
9
8+
6
8
7
8+
7
8
9
7
8
9
8
8+
8
8
7
8
8
7
9
7
8+
7+
8
8
8
7
8
9
8
8
-
7
-
-
6
-
8
-
8
-
-
-
6
-
6
7
9
8
9
8
7
7
9
9
9
-
6
-
7
7
Preplant or Preemergence
Acetochlor1
Acetochlor+atrazine1
Anthem
Anthem ATZ
Atrazine
Balance Flexx
Callisto
Corvus
Fierce2,3
Hornet
Instigate
Lumax/Lexar EZ
Metolachlor1
Metolachlor + atrazine1
Outlook
Prequel2
Python
Resolve Q/Crusher
Sharpen2
Simazine
SureStart/TripleFlex2
Valor3
Verdict2
Zemax
Zidua
Preemergence
Lorox/Linex
Pendimethalin
1Acetochlor, alachlor, metolachlor, and s-metolachlor, and premixes of these with atrazine are available from a number of manufacturers - see corn herbicide descriptions for
more information. Broadleaf weed control ratings assume an atrazine rate of 1.5 lbs ai/A - the atrazine rate in some premix products may be lower.
2SureStart/TripleFlex, Verdict, Sharpen, Fierce, and Prequel are intended for use in planned preemergence followed by postemergence programs, and ratings indicate earlyseason effectiveness, not full-season control. PRE application of these products should be followed with a POST application of Liberty, glyphosate, or other herbicides as
necessary.
3Valor and Fierce must be applied at least 7 days before corn planting. Use only in no-till fields.
Corn
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for additional information on site of action classification.
32
Table 5. Weed Response to Postemergence Herbicides in Corn—Grasses
Site of Action
Crop Tolerance
Barnyardgrass
Crabgrass
Fall Panicum
Field sandbur
Giant Foxtail
Yellow Foxtail
Shattercane
Seedling Johnsongrass
Rhizome Johnsongrass
Quackgrass
Woolly cupgrass
Yellow Nutsedge
Corn
Grasses
4
14
5
6
2
2
5
5/6
14
27
9/28
5/27
2/27
4
4/5
9
9/27/15
2/4
28
5/27
27
5/27
5/6
10
2
2/4
2
2/27
2
14
4/5
14/27
2
4
4/19
2
4
4
2/4
2
2
1
0
2
2
1
1
2
1
1
1
1
2
2
0
1
1
0
0
0
0
1
0
1
2
1
1
1
2
2
2
2
1
1
1/2
0
1
2
7
7
8
8
8
9
7
8
8
8
6
8+
7
7
6
8
-
7*
8
7*
8
8
9
7
8
8
8
8
4
7*
6
-
8
7
8
8
8
9
6
6
8
8+
7
7
7
7
6
8
-
6
6
9
8
9
9
6
6
7
8
6
6
6
8
-
8
7
7
9
8+
9
9
7+
8+
7
8
8
9
6
7
7
6
6
6
9
-
8
7
7
9
9
9
9
7
7+
9
9
6
9
6
7
7
6
6
6
9
-
9
7
9
8
9
9
6
6
8
8
8
9
9
7
7
9
9
-
9
7
9
8
9
9
7
7
8
8
8
9
9
7
7
9
9
-
7
9
7
9
9
7
7
7
9
6
6
8
-
7
8+
9
7
9
9
7
7
6
9
7
7
8
-
7
9
6
9
9
6
6
7+
7+
8+
8
7
7
7
-
7
8
6
7
7
7
8+
6
9
9
Postemergence
2,4-D
Aim
Atrazine
Basagran/Broadloom
Beacon
Bestow
Bromoxynil
Bromoxynil+Atrazine
Cadet
Callisto/Zemax
Callisto GT2
Callisto Xtra
Capreno
Dicamba
Dicamba+atrazine
Glyphosate2
Halex GT2
Hornet
Impact/Armezon
Impact/Armezon + atrazine
Laudis
Laudis + atrazine
Laddok
Liberty1
Nicosulfuron
NorthStar
Permit/Sandea/Halomax
Realm Q
Resolve Q
Resource
Shotgun
Solstice
Spirit
Starane
Status
Steadfast Q
Stinger
WideMatch
Yukon
1Apply to Liberty Link (glufosinate-resistant) corn only.
2Apply to glyphosate-resistant (Roundup Ready, AgriSure GT, etc) corn only.
*Large crabgrass only
33
Table 6. Weed Response to Postemergence Herbicides in Corn—Broadleaf Weeds
Black Nightshade
Burcucumber
Cocklebur
Common Ragweed
Common ragweed (group 2-R)
Giant Ragweed
Giant ragweed (group 2-R)
Jimsonweed
Kochia
Lambsquarters
Lambsquarters (group 5-R)
Palmer amaranth (group 2-R)
Palmer amaranth (group 2+9-R)
Pigweed (redroot/smooth)
Smartweed
Velvetleaf
Waterhemp (group 2-R)
Waterhemp (group 2+9-R)
Waterhemp (group 2+9+14-R)
9
8
9
6
8
9
7
7
8
8
7
9
9
6
8
7
7
8
7
8
8
8
8
8
6
7
9
8
7
9
9
6
9
8
7
8
9
8
9
9
9
9
9
9
8
9
8
9
7
9
9
9
9
8
9
9
9
9
9
8
7
8
8
7
7
8
9
7
9
8
8
8
8
7
9
8
8
6
7+
8
7
8
6
8
8
9
7+
7
8
9
7
7
7
7
7
9
9
9
9
6
9
9
7+
9
9
8
9
9
9
9
9
8
9
8
9
9
9
9
9
8
6
7
9
8
9
8
9
6
9
9
9
9
6
9
7
9
6
9
9
7
9
9
8
9
9
8+
9
9
7
9
8
9
9
9
9
8
8
6
7
9
7
9
9
9
9
9
9
9
6
9
7
9
9
7
9
9
8
9
9
8+
9
9
7
9
8
9
9
9
7
7
7
9
7
9
9
9
9
7
9
8
6
9
8
9
8
9
9
8
9
9
8+
8+
9
7
9
8
9
9
9
9
8
8
9
8
9
9
9
9
9
9
8
6
8
9
8
9
9
8
9
9
8+
8+
9
7
9
8
9
9
9
6
8
9
8
9
9
9
7
7
9
9
9
9
9
9
9
9
9
9
9
9
9
7
9
9
9
9
9
9
8
9
8
9
7
9
9
9
7
9
6
8
8
9
7+
7+
9
7
8
7+
8
9
6
8
8
9
8+
8
9
8
8
7
8+
9
8
9
9
8
8
7
8
7+
8
8
8
9
8
9
8
9
7
9
6
6
9
9
7
9
9
9
9
8
9
8+
9
7+
9
9
9
9
9
7
9
9
7
7
9
9
6
9
8
9
7
6
6
9
9
7
9
9
9
9
8
9
8+
9
7+
9
9
9
9
5
7
9
9
7
7
9
9
6
9
8
8
8+
8
8
9
9
8
8
9
8
9
8
9
8
9
7+
8
7
8
8
9
8
7+
8
8+
8
8
8
9
8
8
9
8
8
9
8
9
7+
8
7
8
8
8
8
7+
9
8+
9
9
8
7
9
8
8
9
9
9
8
9
9
9
7+
9
9
9
9
9
8
9
9
9
9
8
9
9
9
9
9
9
9
6
9
9
8
6
8
9
9
9
9
8
8
9
8
9
9
8
9
8
9
9
9
8
9
7
9
6
9
9
8+
7
8+
7
7
9
8
9
8
8+
8
6
8
9
9
9
9
9
9
7+
9
8
9
8+
9
9
9
9
9
8
8+
8
9
7
9
8+
9
8+
8
8
8
9
8
8+
8
8
9
9
8
8
9
9
9
8
9
8
9
7+
8
7
8
8
9
8
7+
8
8+
8
8
8
9
8
8
9
8
8
9
8
9
7+
8
7
8
8
9
8
7+
8
8+
8
8
8
9
8
8
9
8
8
9
8
9
7+
8
7
8
8
8
8
7+
Postemergence
2,4-D
Aim
Atrazine
Basagran/Broadloom
Beacon
Bestow
Bromoxynil
Bromoxynil+Atrazine
Cadet
Callisto/Zemax
Callisto GT2
Callisto Xtra
Capreno
Dicamba
Dicamba+atrazine
Glyphosate2
Halex GT2
Hornet
Impact/Armezon
Impact/Armezon + atrazine
Laudis
Laudis + atrazine
Laddok
Liberty1
Nicosulfuron
NorthStar
Permit/Sandea/Halomax
Realm Q
Resolve Q
Resource
Shotgun
Solstice
Spirit
Starane
Status
Steadfast Q
Stinger
WideMatch
Yukon
1Apply to Liberty Link (glufosinate-resistant) corn only.
2Apply to glyphosate-resistant (Roundup Ready, AgriSure GT, etc) corn only.
*Large crabgrass only
Corn
Annual Morningglory
Broadleaf Weeds
34
Corn
Corn: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
AAtrex/atrazine
4L
2 - 4 pt
90DF
1.1 - 2.2 lbs
в– в– Site of action: group 5 (see pages 14-15).
в– в– Atrazine is generally applied at a rate of 1.4 to 2 pounds active ingredient per acre to control broadleaf weeds.
в– в– Rates approaching 2 pounds active ingredient can improve control of velvetleaf, giant ragweed, cocklebur, and
morningglory. Velvetleaf can be effectively controlled when atrazine is mixed with Balance, Callisto, or Hornet, but
the latter three weeds are most effectively controlled with a combination of preemergence and postemergence
herbicides. Atrazine will not control fall panicum, regardless of rate.
в– в– Maximum soil-applied rate on soils not highly erodible is 2 pounds of active ingredient per acre. Maximum rate on
highly erodible soils is 2 pounds active ingredient on fields with at least 30% crop residue, and 1.6 pounds active
ingredient on fields with less than 30% crop residue. Soil applications may be followed with a postemergence application of atrazine, but total of all treatments cannot exceed 2.5 pounds active ingredient per acre per year.
в– в– Preplant application of atrazine with COC and/or UAN can control small, emerged annual weeds.
в– в– Plant only corn or sorghum the year (including fall) of atrazine application.
в– в– Where oats, forage legumes, or forage grasses will be planted the following spring, do not apply more than 0.8
pounds active ingredient per acre.
Herbicide
Formulation
Acetochlorvarious
в– в– Acetochlor (plus safener) is sold under various trade names, including Harness, Breakfree NXT, Surpass, Degree,
Confidence, Warrant, and Volley.
в– в– Acetochlor controls annual grasses, pigweed, and black nightshade, and control or suppresses yellow nutsedge,
lambsquarters, and common ragweed. Control of lambsquarters and common ragweed will generally be less effective compared to most broadleaf herbicides, but more effective than other acetamide herbicides.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Can be applied to field corn, popcorn, and production seed corn, but should generally not be used on corn seed
stock. See labels for precautions. Acetochlor can be applied preplant or preemergence to sweet corn, but not
postemergence.
в– в– Degree is an encapsulated product that can provide a longer period of annual grass control compared to other
acetochlor products.
в– в– Most acetochlor products can be applied after planting but prior to weed emergence, and before corn height exceeds 11 inches. Warrant can be applied anytime after corn has emerged until corn reaches 30 inches in height. All
acetochlor products except Degree must be applied using water as the spray carrier after the corn has emerged.
в– в– Degree or Degree plus atrazine can be applied to emerged corn in water or UAN, but corn should not exceed 6
inches in height if fertilizer solution is used as the carrier. Do not apply in fertilizer solution when air temperatures
exceed 85 degrees. Mixtures with products other than atrazine should be applied only in water if the corn has
emerged. Leaf burn may occur when acetochlor is applied to emerged corn.
Degree 3.8L Use Rates (pts/A)a
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
2.25 to 3.25
3.25
Medium
3.25 to 4.25
3.25 to 4.25
Fine
3.25 to 4.25
4.25 to 5
a. On soils with 6 to 10% organic matter, use 4.25 to 6.25 pts/A.
35
Corn: Soil-Applied Herbicides — Preplant or Preemergence
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
1.5 to 2.25
1.5 to 2.5
Medium
1.5 to 2.5
1.5 to 2.5
Fine
1.5 to 2.75
2 to 3
a. Use higher end of rate range if OM content is at higher end of rate range or under anticipated heavy weed infestations.
Breakfree NXT/Surpass NXT/Volley 6.4EC Use Rates (pts/A) in Reduced or No-till System or Conventional System When Applied More than 14 Days Before Planting
Soil Texture Group
Less Than 3% OM
3% or More OM
Coarse
2
2
Medium
2 to 2.5
2.25
Fine
3
3
Warrant Use Rates (qt/A)
Soil Texture
Soil Organic Matter Content
Less than 3%
3% or greater
Coarse
1.5 to 2
2
Medium
1.5 to 2.75
2.0 to 2.75
Fine
1.5 to 2.75
2.75 to 3
Herbicide
Formulation
Product Rate Range
Acetochlor + atrazine
Various
в– в– Acetochlor plus atrazine (plus safener) is sold under various trade names, including Harness Xtra, Degree Xtra, Fultime, Keystone, Confidence Xtra, Breakfree ATZ, and Volley ATZ. These premix products control annual broadleaf
and grass weeds in corn. The ratio of atrazine to acetochlor varies among products, and some products require the
addition of atrazine or another broadleaf herbicide for effective control of broadleaf weeds.
в– в– Degree Xtra and Fultime are encapsulated formulations that can provide a longer period of annual grass control
compared to other acetochlor products.
в– в– Site of action: group 5 (atrazine), group 15 (acetochlor). See pages 14-15.
в– в– Can be applied to field corn, popcorn, and production seed corn, but should generally not be used on corn seed
stock. See labels for precautions. Can be applied preplant or preemergence to sweet corn, but not postemergence.
в– в– Can be applied after planting and before corn height exceeds 11 inches and before weeds reach the 2-leaf stage.
When mixing with postemergence herbicides to control larger weeds, follow the most restrictive label with regard
to maximum corn size.
в– в– All acetochlor products except Degree Xtra should be applied using water as the spray carrier after the corn has
emerged.
в– в– Degree Xtra can be applied in water or UAN, but corn should not exceed 6 inches in height if fertilizer solution is
used as the carrier. Do not apply in fertilizer solution when air temperatures exceed 85 degrees. Mixtures with
Corn
Breakfree NXT/Surpass NXT/Volley 6.4EC Use Rates (pts/A) in
Conventional Tillage Systems When Applied within 14 Days before Plantinga
36
Corn
Corn: Soil-Applied Herbicides — Preplant or Preemergence
products other than atrazine should be applied only in water if the corn has emerged. Leaf burn may occur when
applied to emerged corn.
в– в– Can be mixed with Balance to improve control of velvetleaf, annual grasses, triazine-resistant lambsquarters, and
burcucumber. See Balance description for precautions to avoid crop injury.
Degree Xtra 4L Use Rates (qts/A)
Soil Texture Group
Coarse
2.9
Mediuma
2.9 to 3.7
Fine
3.2 to 3.7
a. In areas of heavy weed pressure rates can be increased to 4.3 qts/A.
FulTime NXT Use Rates (qts/A) in Conventional Tillage Systems When Applied within 14 Days Before
Planting
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
2.25 to 2.7
2.7 to 3
Medium
2.7 to 3.3
3 to 3.3
Fine
3 to 3.5
3 to 5
Harness Xtra 5.6L/Confidence Xtra 5.6L Broadcast Rates (qts/A)a
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
1.4
1.75
Medium
1.75 to 2.4
2.3 to 2.6
Fine
2.3 to 2.6
2.3 to 3.0
a. In areas of heavy infestations use up to 2.3 qts/A on coarse-textured soils and 2.3 to 3.0 qts/A on medium- and fine-textured soils, but do not exceed 2.4 qts/A on highly
erodible soils with less than 30% plant residue.
Breakfree NXT ATZ/Keystone NXT/Volley ATZ 5.25L Use Rates in Conventional Tillage (qts/A)
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
2.2 to 2.4
2.4 to 2.6
Medium
2.4 to 2.8
2.6 to 2.8
Fine
2.6 to 3
2.6 to 3.4
Herbicide
Formulation
Anthem2.15L
Anthem ATZ
4.5L
в– в– Anthem (pyroxasulfone + fluthiacet-methyl) and Anthem ATZ (atrazine + pyroxasulfone + fluthiacet) can be applied
preplant, preemergence, or early postemergence in field corn, seed corn, popcorn, and sweet corn for residual control of annual grasses and broadleaf weeds. These products should be combined with other preemergence corn
herbicide(s) to improve the longevity and spectrum of weed control, or followed with a postemergence herbicide
treatment.
в– в– Site of action: Anthem - group 14/15; Anthem ATZ - group 5/14/15 (see pages 14-15).
в– в– Corn seed must be planted a minimum of one inch deep.
37
Corn: Soil-Applied Herbicides — Preplant or Preemergence
Anthem Broadcast Rates (oz/A)a
Soil Texture Group
Coarse
Medium
Fine
Less than 3% OM
7-8
8 - 10
9 - 11
3% or Greater OM
7-8
8 - 11
10 - 13
a. Rates may increase when applied more than 14 days prior to planting, and decrease when used postemergence - see label.
Anthem ATZ Broadcast Rates (pt/A)a
Soil Texture Group
Coarse
Medium
Fine
Less than 3% OM
1.75 - 2
2 - 2.5
2.25 - 3
3% or Greater OM
1.75 - 2
2 - 2.75
2.5 - 4
a. Rates may increase when applied more than 14 days prior to planting, and decrease when used postemergence - see label.
Herbicide
Formulation
Balance Flexx
2L
в– в– Balance Flexx (isoxaflutole + cyprosulfamide, a safener) can be applied preplant, preemergence, or early postmergence (up to V2 corn) for control of annual broadleaf weeds and early-season control of annual grasses. Balance
Flexx can help control cocklebur, giant ragweed, and morningglory in mixtures with atrazine.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Can be applied up to 30 days prior to planting of LibertyLink, glyphosate-resistant, or Clearfield hybrids, where a
postemergence treatment is planned.
в– в– Preplant application of of Balance Flexx plus atrazine (1 lb ai/A) will control small, emerged annual weeds (3 inches
or less) in no-till, including field pennycress, shepherd's-purse, chickweed, henbit, and marestail. Apply with COC or
MSO. Can be mixed with 2,4-D, Gramoxone, or glyphosate for improved burndown activity on larger weeds.
в– в– Postemergence application of Balance Flexx will not generally control weeds larger than the 1-leaf stage, but can be
mixed with atrazine to improve control. Do not apply with adjuvants or other herbicides after corn has emerged.
в– в– Isoxaflutole has occasionally injured corn, especially during extended periods of cold, wet conditions during corn
seed germination and early crop development. The risk of injury is reduced with Balance Flexx due to the inclusion of a safener. To reduce the risk of injury, do not exceed recommended rate for soil type, plant corn at least 1ВЅ
inches deep, and make sure seed is completely covered with soil and the seed furrow is firmed.
в– в– Consult seed company for information on inbred tolerance to isoxaflutole before using Balance Flexx on seed corn
inbreds.
Balance Flex Use Rates (floz/A)
Timing
8 to 21 days before planting
0 to 7 days before planting or early POST
Soil Texture Group
Coarse
Medium
Fine
Organic matter
Less than
Greater Less than Greater Less than
Greater than
1.5%
than 1.5%
1.5%
than 1.5%
1.5%
1.5%
4.0
5.0
6.0
6.0
6.0
6.0
3.0
4.0
5.0
5.0
6.0
6.0
Corn
в– в– Anthem will not generally provide adequate control of emerged weeds when applied early postemergence. The
addition of atrazine in Anthem ATZ improves activity on emerged weeds but will generally still require the addition
of glyphosate or other postemergence herbicide.
38
Corn
Corn: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
Callisto
4L
6 - 7.7 oz
в– в– Callisto (mesotrione) can be applied preplant or preemergence for control of annual broadleaf weeds, including
lambsquarters (including triazine-resistant), Pennsylvania smartweed, pigweeds, waterhemp, velvetleaf, and black
nightshade. Callisto can help control giant ragweed, cocklebur, and morningglory in mixtures with atrazine.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Callisto does not control grass weeds, and should be applied in combination with Harness, Dual, TopNotch, or another acetamide grass herbicide, or an acetamide/atrazine premix (Bicep II, Magnum, Degree Xtra, etc.).
в– в– Can be applied preplant, preemergence, or postemergence to field corn, seed corn, sweet corn, and yellow popcorn. Do not apply to white popcorn.
в– в– Postemergence rate should not exceed 3 oz/A. To avoid crop injury, do not apply postemergence with emulsifiable
concentrate herbicides or MSOs.
Herbicide
Formulation
Corvus2.63SC
в– в– Corvus is a premix of isoxaflutole and cyprosulfamide (Balance Flexx), and thiencarbazone-methyl that can be applied preplant, preemergence, or early postmergence (spike to V2 corn) for control of annual broadleaf and grass
weeds. The addition of atrazine will improve control of large-seeded broadleaf weeds such as cocklebur, giant
ragweed, and morningglory.
в– в– Site of action: group 27 (isoxaflutole); group 2 (thiencarbazone). See pages 14-15.
в– в– Corvus rates: coarse-textured soils with less than 2% OM - 3.33 oz; medium- or fine-textured soils and coarse-textured soils with more than 2% OM - 5.6 oz.
в– в– Can be applied up to 30 days prior to planting of LibertyLink, glyphosate-resistant, or Clearfield hybrids, where a
postemergence treatment is planned.
в– в– Preplant application of Corvus can control small, emerged annual weeds (6 inches or less) in no-till, especially when
combined with atrazine. Apply with COC or MSO. Can be mixed with 2,4-D, Gramoxone, or glyphosate for improved burndown activity on larger weeds or weeds not controlled by Corvus and atrazine.
в– в– Postemergence application of Corvus will control small-emerged weeds. Mixing with atrazine will improve control.
Do not apply with adjuvants or other herbicides after corn has emerged
в– в– Corvus should not be applied to corn that will receive soil or seed treatment with organophosphate or carbamate
insecticides. See product label and Table 10 for additional information on herbicide-insecticide interactions.
в– в– Isoxaflutole has occasionally injured corn, especially during extended periods of cold, wet conditions during corn
seed germination and early crop development. The risk of injury is reduced with Corvus due to the inclusion of a
safener. To reduce the risk of injury, do not exceed recommended rate for soil type, plant corn at least 1ВЅ inches
deep, and make sure seed is completely covered with soil and the seed furrow is firmed.
в– в– Consult seed company for information on inbred tolerance to isoxaflutole before using Corvus on seed corn inbreds.
Herbicide
Formulation
Fierce76WDG
в– в– Fierce is a premix of flumioxazin (Valor) and pyroxasulfone (Zidua) that controls or suppresses annual grass and
broadleaf weeds. See Valor and Zidua descriptions for more information.
в– в– The application rate, 3 oz/A, is intended to provide early-season control only. Preplant application of Fierce should
be followed with a broad-spectrum postemergence herbicide treatment.
в– в– Site of action: group 14 (flomioxazin), group 15 (pyroxasulfone). See pages 14-15.
в– в– Fierce can be applied between 7 and 30 days prior to planting field corn. Do not apply to popcorn, sweet corn, or
corn grown for seed.
39
Corn: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Hornet78.5WDG
в– в– Hornet is a premix of flumetsulam (Python) plus clopyralid (Stinger). In addition to the broadleaf weeds controlled
by Python, Hornet controls cocklebur and common ragweed. Expect partial control of giant ragweed.
в– в– Site of action: group 2 (flumetsulam), group 4 (clopyralid). See pages 14-15.
в– в– Hornet can be mixed at a rate of 3 to 4 oz/A with atrazine premix products (Bicep, Harness Xtra, etc) to improve
control of triazine-resistant lambsquarters, giant ragweed, and other broadleaf weeds.
в– в– Apply preplant, preemergence, or at the spike stage. When using the rates shown here, apply before the corn is 2
inches tall. Preplant application with COC can control emerged Canada thistle and small annual broadleaf weeds,
including mustards, shepherd's-purse, ragweeds, and Pennsylvania smartweed.
в– в– Do not apply to sweet corn or popcorn. Corn inbred lines should be tested for crop tolerance before treating large
acreages.
в– в– Preemergence applications of Hornet can occasionally injure corn, primarily when growing conditions are unfavorable soon after application. This injury appears as stunting, temporary yellowing, and reduction in root growth. To
avoid injury, plant at least 1ВЅ inches deep and do not use Hornet in soils with an average of less than 1ВЅ percent
organic matter.
в– в– Soil-applied organophosphate insecticides may increase the risk of crop injury, especially when applied in-furrow.
See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– Corn treated with Hornet that is stressed or damaged by herbicide or other factors should not be treated with Accent, Permit, Basis, Beacon, or other group 2 herbicides.
в– в– Do not apply where soil pH is greater than 7.8. Do not apply to soils with a combination of pH less than 5.9 and
organic matter content greater than 5%.
Hornet WDG Use Rates (oz/A)a
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
4
4 to 5
Medium or Fine
4 to 5
5 to 6
a. Use higher rate in recommended range in areas of high weed infestations.
Herbicide
Formulation
Instigate45.8%WDG
в– в– Instigate is a premix of rimsulfuron (Resolve) and mesotrione (Callisto) for preplant and preemergence control or
suppression of annual grass and broadleaf weeds. Instigate should generally be mixed with an atrazine premix or
similar product to improve the longevity and spectrum of control. Mixing with an atrazine premix results in overall
burndown and residual activity similar to Lexar/Lumax. Can also be applied alone where followed by postemergence herbicides.
в– в– Site of action: group 2 - rimsulfuron; group 27 - mesotrione. See pages 14-15.
в– в– Do not apply to popcorn, sweet corn, or corn grown for seed.
в– в– The rate range is 5.25 to 7 oz/A, but 6 oz/A is the appropriate rate is 6 oz/A for most soils and application situations.
Do not apply to coarse soils with less than 1% OM.
в– в– Can be applied postemergence through the 2-collar corn stage, at rates of 5.25 to 5.4 oz/A. The preferred adjuvant system for postemergence applications is COC or MSO (1% v/v) plus UAN (2 qt/A) or AMS (2 lb/A). NIS can be
Corn
в– в– Use only in no-till fields where last year's crop residue has not been incorporated into the soil. Do not conduct any
tillage operations after the Fierce has been applied.
в– в– Do not apply in a mixture with any of the following herbicides unless following directions on a Valent supplemental
label: flufenacet, metolachlor or s-metolachlor, alachlor, dimethenamid-p, or acetochlor.
40
Corn
Corn: Soil Applied Herbicides — Preplant or Preemergence
used instead of COC/MSO. Consult label for adjuvant recommendations when mixing with other herbicides. Do not
use spray additives that adjust the spray solution pH below 5 or above 9 as rapid product degradation can occur.
Do not use UAN as the spray carrier if corn has emerged.
в– в– Do not apply another HPPD inhibiting herbicide (Callisto, Impact/Armezon, Laudis, Capreno) in the same season
that Instigate was used. To avoid crop injury where using insecticides, consult the label and Table 10 for precautions about herbicide-insecticide interactions.
Herbicide
Formulation
Product Rate Range
Lorox
50DF
2/3 - 3 lb
Linex 4L
2/3 - 3 pts
в– в– Lorox/Linex (linuron) controls broadleaf weeds. Linuron is generally applied at a rate of 3/4 to 1 lb/A in combination
with other corn herbicides for control of triazine-resistant pigweed and lambsquarters.
в– в– Site of action: group 7 (see pages 14-15).
в– в– Do not use on soils with more than 3 percent organic matter.
в– в– Apply after corn planting, but before emergence.
в– в– To avoid injury, corn should be planted at least 1Вѕ inches deep and adequately covered with soil.
в– в– Do not apply to emerged corn.
Herbicide
Formulation
Lumax EZ
3.67L
Lexar EZ
3.7L
в– в– Lumax and Lexar are premixes of atrazine, s-metolachlor (Dual II Magnum), and mesotrione (Callisto) for control of
grass and broadleaf weeds in corn. A use rate of Lexar contains a higher amount of atrazine per acre, compared
with Lumax, and a lower amount of s-metolachlor.
в– в– Site of action: group 5 (atrazine); group 15 (s-metolachlor); group 27 (mesotrione). See pages 14-15.
в– в– Controls most annual broadleaf weeds, but expect partial control of giant ragweed, cocklebur, and annual morningglory.
в– в– Lexar and Lumax have been among the most effective preplant burndown treatments for no-till corn in OSU and
Purdue University research, for control of dandelion and most winter annual weeds.
в– в– Lexar use rates: soils with less than 3% organic matter - 3 qts/A; soils with more than 3% organic matter - 3.5 qts/A.
Lumax use rates: soils with less than 3% organic matter - 2.7 qts/A; soils with more than 3% organic matter - 3.25
qts/A. Rates when followed with a postemergence herbicide application, or applied early postemergence in a
mixture with glyphosate or Liberty: Lexar - 2.25 qts/A; Lumax - 2 qts/A.
в– в– Lumax and Lexar can be applied preplant, preemergence, or postemergence before field and seed corn exceeds
12 inches in height. Broadleaf weeds should be less than 3 (Lumax) or 5 (Lexar) inches tall at the time of postemergence application. Control of emerged grasses (up to 1.5 inches tall) will require additional atrazine.
в– в– Can be applied preplant or preemergence on yellow popcorn and sweet corn.
в– в– NIS can be used when Lumax or Lexar is applied to emerged corn. AMS can be added when mixed with glyphosate or Liberty. Use of COC may result in temporary crop injury. Otherwise, do not apply with MSO or nitrogen
based adjuvants (AMS, UAN, etc), or use fertilizer solution as the carrier after corn has emerged.
в– в– Lumax/Lexar may be applied postemergence in a mixture with glyphosate on glyphosate-resistant corn at a rate as
low as 2 qts/A (Lumax) or 2.25 qts/A (Lexar).
в– в– Applying Lexar/Lumax postemergence to corn treated with Counter insecticide at planting may result in severe crop
injury. See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– If applied after June 1, rotating to crops other than corn or sorghum may result in crop injury.
41
Corn: Soil Applied Herbicides — Preplant or Preemergence
Dual II Magnum, Cinch, Parallel, and Stalwart Use Rates (pts/A)
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
1 to 1.33
1.33
Medium
1.33 to 1.67
1.33 to 1.67
Fine
1.33 to 1.67
1.67 to 2
Herbicide
Formulation
S-metolachlor + atrazine
5.5L
Metolachlor + atrazine
5.5L
в– в– S-metolachlor plus atrazine (Bicep II Magnum, Brawl II ATZ, Cinch ATZ) and metolachlor plus atrazine (Stalwart Xtra,
Parallel Plus, Trizmet) control annual grass and broadleaf weeds in corn.
в– в– Site of action: group 5 (atrazine), group 15 (s-metolachlor/metolachlor). See pages 14-15.
в– в– Can be applied preplant, preemergence, and after corn emergence until corn plants are 5 inches tall and before
weeds exceed the 2-leaf stage. Do not apply using fertilizer solution as the spray carrier after the crop emerges.
Bicep II Magnum, Cinch ATZ, and Stalwarta Use Rates Up to 14 Days Before Planting (qts/A)
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
1.3
1.6
Medium
1.6
2.1
2.1
2.1b
or
2.1 to 2.58
Fine
a. When using Stalwart, use 2.1 to 2.6 qts/A on fine-textured soils when applying on non-erodible land with 30% or more residue cover.
b. Do not exceed this rate on highly with less than 30% plant residue cover.
Herbicide
Formulation
Product Rate Range
Metribuzin 75DF
2 - 5 1/3 oz
4L
3 - 8 oz
в– в– Metribuzin (Dimetric, Tricor) is labeled in combination with other corn herbicides to improve residual control of
broadleaf weeds, including lambsquarters, pigweed, common ragweed, Pennsylvania smartweed, and velvetleaf.
In mixtures with 2,4-D, Gramoxone, and/or atrazine, metribuzin can also improve burndown of emerged weeds in
no-till.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Apply before or after planting, but before corn emergence. Application rates increase when applied more than 10
days before planting.
Corn
Herbicide
Formulation
S-metolachlor7.64E
Metolachlor7.8E
в– в– S-metolachlor (Dual II Magnum, Cinch) and metolachlor (Stalwart C, Parallel) control annual grasses and pigweed,
and control or suppress waterhemp, black nightshade, and yellow nutsedge.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Can be applied preplant or preemergence before the crop and weeds emerge. Can be applied broadcast with
atrazine up to 5-inch corn or as a directed spray up to 12-inch corn, and before grass and broadleaf weeds exceed
the 2-leaf stage. Do not apply using fertilizer solution as the spray carrier after the corn has emerged.
в– в– May be applied up to 30 days before planting as a single application.
в– в– Incorporation to a depth of 2 inches will improve yellow nutsedge control and reduce dependence upon rainfall.
42
Corn
Corn: Soil Applied Herbicides — Preplant or Preemergence
в– в– Observe the following precautions to avoid corn injury: Do not apply where soil pH is 7.0 or greater or on coarsetextured soils with less than 1ВЅ% organic matter; do not apply more than 4 ounces/A of metribuzin 75DF on soils
with less than 2% organic matter; plant corn seed at least 1ВЅ inches deep.
в– в– Metribuzin can be used on field corn and in hybrid seed corn production fields. Both inbred lines should have
known tolerance to metribuzin before using in seed production.
Herbicide
Formulation
Outlook6EC
в– в– Outlook (dimethenamid-P) controls annual grasses and pigweed, and controls or suppresses yellow nutsedge and
black nightshade.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Can be applied after crop emergence, but must be applied before weed emergence, or in a tank mixture with herbicides that control emerged weeds. Do not apply to corn that is more than 12 inches tall.
в– в– May be applied after corn has emerged with surfactant or low rates of nitrogen fertilizer solution. Do not use fertilizer solution as the spray carrier after the crop has emerged. COC should not be added after the crop has emerged
unless specified for a particular tank mixture.
Outlook Use Rates (floz/A)a
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
12 to 14
14 to 18
Medium and fine
14 to 18
18 to 21
a. When making applications 15 to 45 days before planting or applying on muck soils, use 21 fl oz/A.
Herbicide
Formulation
Pendimethalin/Pendimax/Pendant/others3.3EC
Prowl H2O, Satellite Hydrocap
3.8CS
в– в– The active ingredient in these products, pendimethalin, controls annual grasses, pigweed, and lambsquarters
(including triazine-resistant biotypes), and helps control smartweed, velvetleaf, and seedling johnsongrass. Pendimethalin is often combined with atrazine for control of grass and broadleaf weeds where triazine-resistant pigweed
and lambsquarters are a problem.
в– в– Site of action: group 3 (see pages 14-15).
в– в– Can be applied postemergence until field corn is in the V8 stage or is 30 inches tall, and other types of corn are 20
to 24 inches tall. Where the corn canopy prevents spray particles from reaching the soil, use drop nozzles and apply as a directed spray. Postemergence applications provide residual control only, not control of emerged weeds.
в– в– Apply only after planting. Do not incorporate or severe corn injury may result.
в– в– To reduce the risk of corn injury, plant at least 1ВЅ inches deep and ensure good seed to soil contact. Combining
pendimethalin with dicamba may increase the potential for crop injury, especially when corn is under stress from
cool, wet conditions.
Prowl H2O/Satellite Hydrocap Use Rates (pt/A)
Soil Texture
Soil Organic Matter Contenta
Less than 3%
More than 3%
Coarse
2 to 3
3
Medium
3
4
Fine
3 to 4
4
43
Corn: Soil Applied Herbicides — Preplant or Preemergence
Pendimethalin 3.3EC Use Rates (pt/A)
Soil Organic Matter Content
Less than 3%
More than 3%
Coarse
1.8 to 3.6
3.6
Medium
2.4 to 3.6
3.6 to 4.8
Fine
2.4 to 4.8
3.6 to 4.8
The high rates for each soil texture above should be used if heavy weed populations are anticipated, extensive crop residues were present prior to seedbed preparation, or in no-till.
Herbicide
Formulation
Product Rate
Prequel
45WDG
1.66 to 2.5 oz
в– в– Prequel is premix of isoxaflutole (Balance Pro) and rimsulfuron that provides residual control of grass and broadleaf
weeds, and also controls some small (less than 3 inches), emerged weeds in no-till burndown situations. Residual
control can be improved with the addition of atrazine. Control of larger emerged weeds can be improved with the
addition of one or more of the following: 2,4-D, atrazine, glyphosate, or paraquat.
в– в– Site of action: group 2 (flumetsulam); group 27 (isoxaflutole). See pages 14-15.
в– в– This product is intended for use in a planned preemergence followed by postemergence program, and the product rates are not intended to provide full-season weed control. Preemergence or preplant application of Prequel
should be followed by a postemergence application of glyphosate (glyphosate-resistant corn), Liberty (Liberty Link)
corn, or conventional herbicides as needed.
в– в– Use on field corn hybrids only.
в– в– Control of emerged weeds requires the addition of NIS or COC, plus AMS or UAN. When mixed with Liberty or a
glyphosate product that contains adjuvants, no additional NIS or COC is needed.
в– в– Crop injury can increase and rate of crop recovery from injury can slow when corn is growing slowly under adverse
environmental conditions, including extremely wet, cold, or dry soils, high pH, or low fertility. Do not use on coarse
soils with less than 1% organic matter. Application to caorse soils with less than 1.5% organic matter or pH greater
than 7.5 can cause adverse crop response. Plant corn at least 1ВЅ inches deep, and make sure that the seed furrow
is firmed and seed is completely covered with soil.
Herbicide
Formulation
Princep/simazine4L
90DF
в– в– Simazine is often applied at reduced rates in combination with atrazine or atrazine premix products to improve or
extend grass control.
в– в– Site of action: group 5 (see pages 14-15).
в– в– Simazine rates will vary depending upon the herbicides in the mixture, but when used alone, rates are as follows
(for simazine 4L): sand, silt, ot loam with low OM - 4 pts/A; soil with moderate amounts of clay and organic matter 4.8 pts/A; loams high in OM and clay - 6 pts/A.
в– в– Simazine is more effective than atrazine for control of fall panicum and crabgrass, but is less effective for control of
cocklebur, quackgrass, yellow nutsedge, velvetleaf, and giant ragweed.
в– в– Can be applied at a rate of 1 lb active ingredient/A in the fall prior to corn planting for control of winter annual
weeds such as chickweed, mustards, and deadnettle. Apply with 2,4-D for best results. If weeds are more than an
inch or two tall, apply with Gramoxone or glyphosate.
Corn
Soil Texture
44
Corn
Corn: Soil Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Python80WDG
в– в– Python (flumetsulam) controls annual broadleaf weeds, including triazine-resistant lambsquarters and velvetleaf.
Control of common ragweed and cocklebur is variable, and Python does not control giant ragweed or annual
morningglory.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Python use rates range from 0.8 to 1 oz/A in coarse-textured soils, and 0.9 to 1.33 oz/A in medium or fine-textured
soils. Reduced rates of Python can be mixed with atrazine premix products (Bicep, Harness Xtra, etc) to improve
control of triazine-resistant lambsquarters.
в– в– Can be applied postemergence, from spike stage to 20-inch or V6 stage, for residual control of pigweeds, lambsquarters, and velvetleaf.
в– в– Do not apply to soils with a combination of pH less than 5.9 and organic matter content greater than 5%. Do not
apply where soil pH is greater than 7.8.
в– в– Python can occasionally injure corn, primarily when growing conditions are unfavorable soon after application. This
injury appears as stunting, temporary yellowing, and reduction in root growth. To avoid injury, plant at least 1ВЅ inches deep and do not use Python in soils with an average of less than 1ВЅ percent organic matter.
в– в– Soil-applied organophosphate insecticides may increase the risk of crop injury, especially when applied in-furrow.
See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– Corn treated with Python that is stressed or damaged by herbicide or other factors should not be treated with Accent, Permit, Basis, Beacon, or other group 2 herbicides.
в– в– Do not apply to sweet corn or popcorn. Inbred lines should be tested for crop tolerance before treating large acreages.
Herbicide
Formulation
Product Rate Range
Resolve Q
22.4 WDG
1.25 - 2.5 oz
Crusher
50DF
1.0 - 1.8 oz
в– в– Resolve Q/Crusher (rimsulfuron plus thifesnsulfuron) can provide residual control of annual grasses, pigweeds, and
lambsquarters. Can be combined with atrazine or other preemergence herbicides for residual control of additional weeds. Preplant or preemergence application of these products plus atrazine should be followed with a
broad-spectrum postemergence herbicide program.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Preplant application of Resolve Q/Crusher and atrazine can control small, emerged weeds in no-till corn, especially
when mixed with 2,4-D.
Herbicide
Formulation
Sharpen2.85SC
в– в– Sharpen (saflufenacil) controls annual broadleaf weeds in field corn and popcorn. The addition of atrazine will improve control of large-seeded broadleaf weeds such as giant ragweed, morningglory, and cocklebur. Sharpen can
also be added to other preemergence corn products to improve residual control of broadleaf weeds. Do not apply
Sharpen after corn has emerged.
в– в– Site of action: group 14. See pages 14-15.
в– в– This product is intended for use in a planned preemergence followed by postemergence program when applied
alone, and the product rates will nor provide full-season weed control. Preemergence or preplant application of
Sharpen should be followed by a postemergence application of glyphosate (glyphosate-resistant corn), Liberty (Liberty Link) corn, or conventional herbicides as needed.
в– в– Sharpen rates are based on soil texture as follows: coarse - 2 to 2.5 oz; medium - 2.5 to 3 oz; fine - 3 to 3.5 oz.
в– в– Do not apply Sharpen where an at-planting application of an organophosphate or carbamate insecticide us planned
or has occurred because severe injury may occur. See product label and Table 10 for more information on herbicide-insecticide interactions.
45
Corn: Soil Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
SureStart/TripleFlex/TripleFLEX II
4.25L
в– в– SureStart/TripleFlex/TripleFLEX II is a premix of acetochlor, clopyralid (Stinger), and flumetsulam (Python) that provides
residual control of grass and broadleaf weeds.
в– в– Site of action: group 2 (flumetsulam); group 4 (clopyralid); group 15 (acetochlor). See pages 14-15.
в– в– This product is labeled for use only in glyphosate-resistant and Liberty Link corn, and is intended for use in a planned
preemergence followed by postemergence program. Preemergence or preplant application of SureStart/TripleFlex
should be followed by a postemergence application of glyphosate (glyphosate-resistant corn), Liberty (Liberty Link
corn), or conventional herbicides as needed.
в– в– Preplant/preemergence application rates: coarse texture - 1.5 pts; medium texture with less than 3% OM - 1.5 to 1.75
pts; medium texture with >3% OM - 1.75 pts; fine texture - 2 pts.
в– в– SureStart/TripleFlex can also be applied early postemergence (up to 11-inch corn) in a mixture with glyphosate or Liberty, using the appropriate type of corn. This mixture will control emerged weeds and provide residual weed control
after application.
в– в– To reduce risk of crop injury, plant corn at least 1ВЅ inches deep, and make sure seed furrow is closed. Do not use
where soil pH is greater than 7.8 or soil organic matter is less than 1.5%.
в– в– Do not apply Counter insecticide to corn that has been or will be treated with SureStart/TripleFlex. See product label
and Table 10 for more information on herbicide-insecticide interactions.
Herbicide
Formulation
Product Rate Range
Valor SX
51WDG
2 oz
в– в– Valor (flumioxazin) can be applied between 7 and 30 days prior to planting field corn. Valor controls lambsquarters
(including triazine-resistant), black nightshade, and pigweeds. Valor suppresses or provides partial control of common ragweed, morningglory, velvetleaf, waterhemp, smartweed, and some annual grasses.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Do not apply to popcorn, sweet corn, or corn grown for seed.
в– в– Use only in no-till fields where last year's crop residue has not been incorporated into the soil. Do not conduct any
tillage operations after the Valor has been applied.
в– в– Do not apply in a mixture with any of the following herbicides unless following directions on a Valent supplemental
label: flufenacet, metolachlor or s-metolachlor, alachlor, dimethenamid-p, or acetochlor.
Herbicide
Formulation
Verdict5.57EC
в– в– Verdict is a premix of dimethenamid-P (Outlook) and saflufenacil (Sharpen) that controls annual grass and broadleaf
weeds in field corn, popcorn, and seed corn. The addition of atrazine will improve control of large-seeded broadleaf
weeds such as giant ragweed, morningglory, and cocklebur. Do not apply after corn has emerged.
в– в– Site of action: Group 15 (dimethenamid-P); group 14 (Saflufenacil). See pages 14-15.
в– в– This product is intended for use in a planned preemergence followed by postemergence program, and the product
rates are not intended to provide full-season weed control. Preemergence or preplant application of Verdict should
be followed by a postemergence application of glyphosate (glyphosate-resistant corn), Liberty (Liberty Link) corn, or
conventional herbicides as needed.
в– в– Verdict rates for field corn are based on soil texture as follows: coarse - 10 to 12 oz; medium - 13 to 15 oz; fine - 16 to
18 oz. Rates for seed corn: coarse soils - 5 oz; medium to fine textured soils - 5 to 10 oz.
Corn
в– в– Preplant application of Sharpen and atrazine can control small, emerged weeds in no-till, including marestail. Glyphosate should be added when weeds are more than about 4 inches tall and for weeds Sharpen does not control (see label). For control of emerged weeds, apply with MSO (1% v/v) and AMS (8.5 to 17 lbs/100 gallons) or UAN (1.25 to 2.5%
v/v). Use a spray volume of 15 to 20 gpa in no-till burndown situations, or where emerged weeds are present. Flat
fan nozzles are recommended for burndown applications.
46
Corn
Corn: Soil Applied Herbicides — Preplant or Preemergence
в– в– Do not apply Verdict where an at-planting application of an organophosphate or carbamate insecticide us planned
or has occurred to avoid severe injury. See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– Preplant application of Verdict and atrazine can control small, emerged weeds in no-till, including marestail.
Glyphosate should be added when weeds are more than about 4 inches tall and for weeds Verdict does not control
(see label). For control of emerged weeds, apply with MSO (1% v/v) and AMS (8.5 to 17 lbs/100 gallons) or UAN (1.25
to 2.5% v/v). Use a spray volume of 15 to 20 gpa in no-till burndown situations, or where emerged weeds are present. Flat fan nozzles are recommended for burndown applications.
Herbicide
Formulation
Zemax3.76ZC
в– в– Zemax is a premix of mesotrione (Callisto) and s-metolachor (Dual II Magnum) that controls annual grass and broadleaf weeds in corn. The addition of atrazine will improve control of large-seeded broadleaf weeds. See Callisto and
s-metolachlor descriptions for more information.
в– в– Site of action: group 14 (s-metolachlor); 27 (mesotrione). See pages 14-15.
в– в– Can be applied preemergence to most types of corn, including popcorn (yellow only), sweet corn, and corn grown
for seed. Can be applied postemergence to field corn and seed corn only, until corn reaches the 8-leaf stage or is
30 inches tall.
в– в– For postemergence applications, add either NIS (0.25% v/v) or COC (1% v/v). AMS or UAN can be added but this
increases the risk of crop injury. Do not apply with MSO or use UAN as the spray carrier.
в– в– Application rates: 2 qts/A - less than 3% soil OM; 2.4 qts/A - 3% or greater soil OM. Rate can be reduced to 1.6 qt/A
when applied early postemergence with glyphosate (glyphosate-resistant corn) or Liberty (LibertyLink corn).
в– в– Severe crop injury may occur if Zemax is applied postemergence to corn that was previously treated with organophosphate insecticides. See product label and Table 10 for more information on herbicide-insecticide interactions.
Herbicide
Formulation
Zidua85WDG
в– в– Zidua (pyroxasulfone) can be applied preplant, preemergence, or early postemergence in field corn, seed corn,
popcorn, and sweet corn for residual control of annual grasses and small-seeded broadleaf weeds. This product
should generally be combined with other preemergence corn herbicide(s) to improve broadleaf weed control, or
followed with a postemergence herbciide treatment.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Application rates based on soil texture: coarse - 1.5 to 2.75 oz; medium - 2 to 3 oz; fine - 2.5 to 4 oz. The label allows rates lower than those listed here when applied postemergence or used in a planned sequential (PRE + POST)
program.
в– в– Corn seed must be planted a minimum of one inch deep.
в– в– Early postemergence applications will not control emerged weeds.
47
Corn: Postemergence Herbicides — Contact
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
AAtrex/atrazine
4L
1.5 - 2 qt
1 - 1.5 qt
90DF
1.67 - 2.22 lb
1.1 - 1.7 lb
в– в– Site of action: group 5 (see pages 14-15).
в– в– Maximum rate for postemergence application to fields without soil-applied atrazine in the same year is 2 pounds
active ingredient/A. When applied postemergence to fields with soil-applied atrazine the same year, total amount of
atrazine applied may not exceed 2.5 pounds active ingredient.
в– в– For annual grass control, apply 2 lbs ai/A when grasses are no more than 1ВЅ inches tall. Atrazine will not control fall
panicum.
в– в– For control of broadleaf weeds, rates of 1.2 pounds active ingredient may be sufficient. Apply until broadleaf weeds
are 4 inches tall.
в– в– Apply with COC (1 qt/A) for best results. Mix atrazine with water first, and add oil last.
в– в– Apply before the crop reaches 12 inches in height.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
Herbicide
Basagran/Broadloom
Formulation
4L
Product Rate Range
1.5 - 2 pt
With Glyphosate or Liberty
1.5 - 2 pt
в– в– Basagran/Broadloom (bentazon) is a contact herbicide that controls annual broadleaf weeds, including cocklebur,
velvetleaf, and Pennsylvania smartweed. Controls or suppresses Canada thistle and yellow nutsedge.
в– в– Site of action: group 6 (see pages 14-15).
в– в– For best results, apply with COC when weeds are in the 2- to 6-leaf stage.
в– в– Apply in combination with atrazine for control of pigweed, lambsquarters, and ragweeds.
в– в– Add COC (1 qt/A) if mixing with glyphosate.
Corn
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Aim
2EC
0.5 -1 oz
Not addressed on label
в– в– Aim (carfentrazone-ethyl) is a contact herbicide that controls black nightshade, velvetleaf, redroot pigweed, and
small annual morningglories and lambsquarters. Aim is often added to herbicide programs to improve control of
velvetleaf.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply when weeds are 1 to 4 inches tall for best results. Velvetleaf can be controlled up to 36 inches tall. Apply
broadcast before corn exceeds the 8-collar stage, and as a directed spray with drop nozzles up to the 14-collar
stage.
в– в– Apply with NIS (0.25% v/v). UAN (2 to 4 gallons/100 gallons) or AMS (2 to 4 lbs/A) can be added if recommended for
use with other herbicides in a mix with Aim. The label does allow use of COC under dry conditions and in specific
tank mixtures. Add Aim to the spray tank before adding other products. Application with Buctril may cause unacceptable crop injury.
в– в– Aim can be applied with drop nozzles to seed corn production fields. Avoid directing herbicide into the whorl.
в– в– Apply in a spray volume of 10 to 20 gpa with a pressure of 20 to 40 psi. Flat fan nozzles are recommended for
adequate spray coverage.
в– в– Aim usually causes leaf speckling and necrosis. The severity of injury varies with environmental conditions, adjuvants, and other herbicides in the mixture. To reduce injury, 1) do not apply within 6 to 8 hours of rain, 2) make
sure spray nozzles are positioned at least 18 inches above the crop, and 3) avoid direction of excessive amounts of
herbicide into corn whorls.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
48
Corn
Corn: Postemergence Herbicides — Contact
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Bromoxynil
2S
1 - 1.5 pt
Not labeled
в– в– Bromoxynil is sold under various trade names, including Buctril, Moxy, and Broclean. Bromxynil is a contact herbicide that controls many annual broadleaf weeds, including black nightshade, cocklebur, ragweeds, lambsquarters,
and smartweed, but is weak on pigweed and large velvetleaf.
в– в– Site of action: group 6 (see pages 14-15).
в– в– Apply at a rate of 1 pint per acre from corn emergence until tassel emergence. The 1ВЅ-pint rate may be applied after
corn reaches the 4-leaf stage and before tassel emergence. Maximum corn size at the time of application varies
with the tank-mix partner.
в– в– Do not apply to seed corn inbreds or popcorn prior to the 3-leaf stage.
в– в– Do not use surfactant or crop oil when applying bromoxynil alone or with most other herbicides. NIS and UAN are
allowed in some mixtures.
в– в– Apply in a minimum volume of 10 gpa at a minimum pressure of 30 psi using flat fan nozzles.
в– в– May cause corn leaf burn, but effects are usually temporary.
Herbicide
Formulation
Product Rate Range
Bromoxynil + atrazine
3L
1ВЅ - 3 pt
в– в– Bromoxynil plus atrazine is sold under various trade names. It controls most annual broadleaf weeds.
в– в– Site of action: group 5 (atrazine); group 6 (bromoxynil). See pages 14-15.
в– в– Can be applied at a rate of 1ВЅ to 2 pints per acre after corn emergence and before corn is 12 inches tall. The 3-pint
rate may be applied after corn reaches the 4-leaf stage and before corn is 12 inches tall.
в– в– Do not use surfactant, crop oil, liquid fertilizers, or other additives when applying Buctril/atrazine or Moxy/atrazine
alone or with most other herbicides. NIS and UAN are allowed in some mixtures.
в– в– Apply in a volume of at least 10 gallons per acre at a minimum pressure of 30 psi using flat fan nozzles.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Cadet
0.91EC
0.4 - 0.9 oz
0.4 - 0.6 oz
в– в– Cadet (fluthiacet-methyl) is a contact herbicide that controls velvetleaf, and controls or suppresses small lambsquarters, pigweeds, black nightshade, and annual morningglory at the 0.9 oz rate.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Can be applied to field corn and seed corn from prior to planting up to 48 inches tall. Apply before tassel emergence.
в– в– Apply with NIS (0.25% v/v), COC, or MSO (1 to 2 pts/A). UAN (1 to 2 qts/A) or AMS can be added. When combined
with other herbicides, Cadet can generally be applied with any adjuvants required for those herbicides.
в– в– Apply in a minimum spray volume of 15 gpa and pressure of 20-40 psi. Increase volume and pressure in dense
crop and weed canopies.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
Herbicide
Formulation
Product Rate Range
Laddok S-12
5L
1 1/3 - 2 1/3 pt
в– в– Laddok/Headline is a 1:1 premix of bentazon (Basagran) plus atrazine for control of most broadleaf weeds, and suppression or control of yellow nutsedge, Canada thistle, and some perennial vines.
в– в– Site of action: group 5 (atrazine); group 6 (bentazon). See pages 14-15.
в– в– Application rate varies with weed species and size. Apply with UAN, AMS, or nonphytotoxic oil concentrate. The
label allows combinations of spray additives, which vary with the weed species present. UAN or AMS should be
added when velvetleaf is the target weed, and may also improve control of cocklebur and Pennsylvania smartweed.
49
Corn: Postemergence Herbicides — Contact
в– в– в– в– в– в– Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Resource
0.86EC
4 to 6 oz (broadcast)
Glyphosate: 2 - 4 oz
4 to 8 oz (directed)
Liberty: 2 oz
в– в– Resource (flumiclorac) is a contact herbicide that controls velvetleaf (up to 10 inches tall) and pigweeds. Control of
lambsquarters is variable, and some other broadleaf weeds will be suppressed.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply when corn is in the 2- to 10-leaf stage and broadleaf weeds are in the 2- to 3В­-leaf stage for best results. Use
a directed spray if corn size prevents adequate spray coverage of weeds.
в– в– COC should be included when Resource is applied alone. Use 1 pint/A for broadcast application and 1 quart/A for
directed application. UAN or AMS can be added to improve control of large velvetleaf. Adjuvant recommendations
vary with the other herbicides in the mixture. See the label for more information.
в– в– Apply in a spray volume of at least 10 gpa with a spray pressure of 30 to 60 psi.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
Corn
в– в– COC should also be added when common lambsquarters, common ragweed, Canada thistle, yellow nutsedge, or
field bindweed is present.
Apply in a spray volume of at least 10 gpa with a minimum pressure of 40 psi. Increasing the spray volume (up to 50
gpa) will improve control when the crop and weed foliage is dense.
To suppress Canada thistle, apply 2 1/3 pints when thistle plants are 8 to 10 inches tall until the bud stage.
A single application of 2 1/3 pints of Laddok can suppress yellow nutsedge that is 1 to 4 inches tall.
Provides better control of velvetleaf, annual morningglory, lambsquarters, and pigweed than Basagran alone, but is
no more effective on triazine-resistant lambsquarters.
50
Corn
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate
Beacon
75DF
3/8 - 3/4 oz 3/8 - 3/4 oz
в– в– Beacon (primisulfuron) is a systemic sulfonylurea herbicide that controls or suppresses annual and perennial grasses and controls annual broadleaf weeds. Beacon provides only partial control of foxtail species and may be less
effective than Accent for rhizome johnsongrass and quackgrass control, but is generally more effective than Accent
for broadleaf weed control. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Mixtures of Beacon plus dicamba or 2,4-D will suppress a number of perennial broadleaf weeds.
в– в– Beacon is labeled for use on field corn, popcorn, and seed corn. Popcorn and inbred lines grown for seed may be
severely injured by Beacon and should be thoroughly tested for potential sensitivity to Beacon before treating large
acreage. Do not use Beacon on sweet corn.
в– в– Apply broadcast or as a directed spray when field corn is between 4 and 20 inches tall, and as a directed spray
after corn is 20 inches tall and before tassel emergence. All applications to inbred lines and popcorn should be
made post-directed or semi-directed (nozzles positioned to avoid placing spray in whorl) after corn is 10 inches tall
but before tassel emergence.
в– в– Apply with NIS (0.25% v/v) or COC (1 to 4 pints per acre); COC is generally the preferred additive. Liquid nitrogen
fertilizer (2 to 4 quarts/A) or AMS (2 to 4 lbs/A) may be added, but should not substitute for surfactant or oil concentrate. COC plus nitrogen fertilizer can be use when mixing with atrazine, Accent, or 2 oz/A or less of dicamba.
Mixtures with most other herbicides should be applied with NIS. See label for detailed information on mixtures with
other herbicides.
■■Apply when grasses are at the following heights: shattercane and seedling johnsongrass — 4 to 12 inches; rhizome
johnsongrass — 8 to 16 inches; quackgrass — 4 to 8 inches; fall panicum — less than 2 inches. Beacon will control
common and giant ragweed that are 2 to 9 inches tall. Most other broadleaf weeds should be 1 to 4 inches tall
when Beacon is applied.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Bestow
25DF
0.5 - 2.0 oz
Gly - 1.0 oz; Lib -0.75 oz
в– в– Bestow (rimsulfuron) controls or suppresses small (1 to 2 inch) annual grass and broadleaf weeds, including foxtails,
lambsquarters, and pigweed. When mixed with glyphosate in postemergence treatments to glyphosate-resistant
corn, Bestow provides residual control of annual grasses and some small-seeded broadleaf weeds The 1.0 oz rate
is recommended for most situations. .
в– в– Site of action: group 2 (see pages 14-15).
в– в– Can be applied broadcast to field corn with up to 5 collars, or up to 12 inches tall (whichever is more restrictive).
в– в– Apply with NIS (0.25% v/v) plus UAN (2 qt/A) or AMS (2 lb/A). No additional adjuvants are needed when applying
with Liberty or a glyphosate product that contains surfactant.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Callisto
4L
3 oz
3 oz
в– в– Callisto (mesotrione) is a systemic herbicide that controls annual broadleaf weeds. The addition of atrazine (1/2 pint)
improves control of a number of weeds, and is required for consistent control of common ragweed and morningglory. Where corn is more than 12 inches tall and atrazine cannot be used, a mixture of Callisto plus bromoxynil can
improve control of ragweeds.
51
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Callisto Xtra
3.7L
20 to 24 oz
20 to 24 oz
в– в– Callisto Xtra is a premix of mesotrione (Callisto) and atrazine that controls annual broadleaf weeds.
в– в– Site of action: group 27 (mesotrione); group 5 (atrazine). See pages 14-15.
в– в– Apply when weeds are less than 5 inches tall for best results. Can be applied to field corn, seed corn, and yellow
popcorn from emergence up to 12 inches tall.
в– в– Apply with COC (1% v/v) or NIS (0.25% v/v) plus UAN (2.5% v/v) or AMS (8.5 lb/100 gallons). COC is the preferred
adjuvant to maximize activity. Do not use MSO (MSO) or MSO blend adjuvants.
в– в– Apply in a spray volume of 10 to 30 gpa, but use a volume of at least 15 gpa if weed foliage is dense.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– Do not apply Callisto Xtra postemergence in a mixture with emulsifiable concentrate grass herbicides, unless specifically addressed under one of the mixture sections of the label, or crop injury may occur.
в– в– Do not use COC or UAN when mixing with Liberty. Do not use UAN, COC or MSO when mixing with glyphosate. If
glyphosate has an adjuvant system, add AMS (8.5 - 17 lb/100 gal). If the glyphosate does not contain adjuvants, add
NIS (0.25% v/v) and AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Capreno
3.45SC
3 oz
Glyphosate - 3 oz
Liberty - 2 oz
в– в– Capreno is a premix of tembotrione (Laudis) and thiencarbazone-methyl that controls annual grass and broadleaf
weeds in field corn and seed corn. This product will provide residual control of grasses also. The addition of atrazine (0.5 lb/A) will generally improve the speed and effectiveness of control.
в– в– Site of action: group 27 (tembotrione), group 2 (thiencarbazone). See pages 14-15.
в– в– Apply with COC (1% v/v, minimum of 1.25 pt/A) and 28% UAN (1.5 qts/A) or AMS (8.5 lbs/100 gallons, minimum of 1.5
lbs/A). High surfactant oil blends at their recommended rates can replace COC, but do not use NIS or MSO.
в– в– Can be applied broadcast from the V1 to V6 stage of corn, and as a directed spray up to V7. Capreno is most
effective when broadleaf weeds are less than 4 to 6 inches tall, and grasses are less than 3 inches tall and not tillering.
Corn
в– в– Site of action: group 27 (see pages 14-15).
в– в– Apply when weeds are less than 5 inches tall for best results. Apply with atrazine (1/2 pint) if weeds are more than
5 inches tall.
в– в– Callisto can be applied to field corn and seed corn up to 30 inches tall or the 8-leaf stage. Callisto plus atrazine can
be applied to corn up to 12 inches tall.
в– в– Apply with COC (1% v/v) plus UAN (2.5% v/v) or AMS (8.5 lb/100 gallons). Do not use MSO (MSO) or MSO blend
adjuvants.
в– в– Callisto can be applied at the rate of 2.5 oz/A when weeds are less than 5 inches tall and it is mixed with either
atrazine (0.5 lbs ai/A) or glyphosate.
в– в– Apply in a spray volume of 10 to 30 gpa, but use a volume of at least 20 gpa if weed foliage is dense.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– Do not apply Callisto postemergence in a mixture with emulsifiable concentrate grass herbicides, unless specifically
addressed under one of the mixture sections of the label, or crop injury may occur.
в– в– Do not use COC when mixing with Liberty. Do not use UAN, COC or MSO when mixing with glyphosate. If glyphosate has an adjuvant system, add AMS (8.5 - 17 lb/100 gal). If the glyphosate does not contain adjuvants, add NIS
(0.25% v/v) and AMS.
52
Corn
Corn: Postemergence Herbicides — Systemic
в– в– Apply in a minimum spray volume of 10 gpa, but use a volume of 15 to 20 gpa if weed foliage is dense.
в– в– Consult seed company for information on inbred tolerance before using Capreno on seed corn inbreds.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– Use 2 oz/A of Capreno and 22 oz/A of Liberty when mixing in Liberty Link corn. Do not use any adjuvants except
AMS.
в– в– Use 3 oz/A of Capreno when mixing with glyphosate in glyphosate-resistant corn. AMS should always be included
with this combination. The addition of a glyphosate-compatible high surfactant oil blend is also recommended, and
required if the glyphosate does not contain adjuvants.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Dicamba
4L
1/2 - 1 pt
Not addressed on label
в– в– Dicamba is sold under a number of trade names, including Banvel, Clarity, Sterling Blue, and Oracle. Dicamba is
a translocated herbicide that controls many annual broadleaf weeds, including pigweeds, ragweeds, black nightshade, cocklebur, and Pennsylvania smartweed. Control of velvetleaf can be variable. Dicamba will control or suppress perennial broadleaf weeds, especially when applied with group 2 herbicides.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply 1/2 to 1 pint when corn is in the spike to five-leaf stage, or until corn is 8 inches tall, whichever occurs first. Do
not apply more than 1/2 pint on coarse-textured soils. If the 6th true leaf is emerging from the whorl, or corn is more
than 8 inches tall, a rate of 1/2 pint can be applied until corn is 36 inches tall, or until 15 days before tassel emergence. Apply as a directed spray when corn leaves prevent proper spray coverage, or sensitive crops are growing
nearby.
в– в– The 1 pint rate provides limited residual broadleaf weed control.
в– в– Apply with 1/2 to 1 gallon per acre of UAN (28%) when velvetleaf is a target weed. Can be applied with surfactant
or crop oil to improve control in dry growing conditions. Do not apply with crop oil when corn exceeds 5 inches in
height.
в– в– With any dicamba product, risk of corn injury increases when corn exceeds 8 to 10 inches in height. To reduce risk
of injury, make sure nozzle spacing and spray boom height are set to minimize interception of spray by the corn
plants.
в– в– Soybeans and vegetables are extremely susceptible to dicamba drift and vapors. Apply in a spray volume of 20 gpa
at a pressure of less than 20 psi to reduce drift. Do not apply where sensitive crops are growing nearby if winds
over 5 MPH are moving in the direction of sensitive crops, corn is more than 24 inches tall, soybeans are more than
10 inches tall, or soybeans have begun to bloom. Most dicamba products should not be applied when air temperatures on the day of application will exceed 85 degrees.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Dicamba + atrazine premix
3.2L
3 1/2 pt
Not addressed on label
в– в– Dicamba plus atrazine is sold under a number of trade names, including Marksman, Sterling Plus, BanvelK+atrazine, and Stratos. These products control most annual broadleaf weeds, and suppress or control perennial
broadleaf weeds.
в– в– Site of action: group 5 (atrazine), group 4 (dicamba). See pages 14-15.
в– в– Apply when corn is in the spike to five-leaf stage, or until corn is 8 inches tall, whichever comes first. The rate is 3
1/2 pints on medium- or fine-textured soils with at least 2 percent organic matter, and 2 pints on coarse-textured
soils. Provides some residual broadleaf weed control.
в– в– The addition of crop oil, surfactant, or liquid nitrogen fertilizer may improve control, especially when weeds are
drought-stressed. Apply with UAN if velvetleaf is a target weed. Application with crop oils may cause crop injury.
Do not apply with crop oil after corn exceeds 5 inches in height.
в– в– Precautions on spray drift, volatility, and corn injury are the same as for dicamba. See dicamba description for more
information.
53
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Impact/Armezon
2.8L
0.75 oz
0.5 - 0.75 oz
в– в– Impact/Armezon (topramezone) controls many broadleaf weeds, including biotypes resistant to group 2 herbicides,
glyphosate, and triazines. Impact controls or suppress small annual grasses. Impact/Armezon is most effective
when applied in combination with 0.25 to 1.5 lbs ai/A of atrazine. The higher atrazine rates will provide residual
weed control.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Can be applied to field corn, seed corn, popcorn, and sweet corn. Check with seed supplier for information on
tolerance prior to use on inbreds grown for seed production.
в– в– Apply when most broadleaf weeds are emerged and less than 6 inches tall.
в– в– Impact can be applied postemergence up to 45 days before crop harvest. Apply with drop nozzles if the crop canopy prevents adequate spray coverage on weeds.
в– в– For best results, apply with a MSO (1 to 1.5% v/v) plus either UAN (1.25 to 2.5% v/v) or AMS (8.5 to 17 lbs/100 gallons
of water). NIS can be used instead of methylated seed soil if required in mixtures with other herbicides.
в– в– Apply in a minimum spray volume of 10 gpa, and apply in 15 gpa when treating large weeds or high-density weed
infestations.
в– в– Impact/Armezon should not be relied upon to provide complete control of grasses, but can control small (less than
3-inch) grasses that escape preemergence herbicides.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
Corn
Hornet 78.5WDG
2 - 5 oz
2 - 4 oz
в– в– Hornet is a premix of flumetsulam (Python) and clopyralid (Stinger) that controls annual broadleaf weeds, and suppresses certain perennial broadleaf weeds. Hornet controls ragweeds, velvetleaf, cocklebur, Pennsylvania smartweed, and small marestail, but is not effective for control of lambsquarters, pigweeds, black nightshade, and annual
morningglory. The higher rates can suppress or control some perennial weeds, including dandelion and Jerusalem
artichoke.
в– в– Site of action: group 2 (flumetsulam), group 4 (clopyralid). See pages 14-15.
в– в– Hornet will control the above-ground growth of Canada thistle, but may be less effective than labeled rates of
Stinger for long-term control of thistle. Mixing Hornet with Stinger will improve long-term control. Apply before
thistle plants are in the bud stage for best results.
в– в– Apply broadcast when weeds are 2 to 8 inches tall and field corn is up to 20 inches tall or at the 6-collar stage,
whichever occurs first. Hornet can be applied as a directed postemergence application using drop nozzles to corn
that is 20 to 36 inches tall.
в– в– Apply with NIS (1 quart/100 gallons) or COC (1 gallon/100 gallons). Under dry conditions, the addition of UAN (2 1/2
gallons/100 gallons) may improve control.
в– в– Apply in a spray volume of 10 to 40 gpa with a spray pressure of 20 to 40 psi.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– Do not apply to corn that shows symptoms of injury from previously applied herbicides. Corn inbred lines may be
injured by Hornet.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
54
Corn
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Laudis
3.5L
3 oz
Glyphosate: 3 oz
Liberty: 2 - 3 oz
в– в– Laudis (tembotrione) controls many broadleaf weeds, including biotypes resistant to groups 2, 5, and 9. Laudis
controls or suppress small annual grasses. Laudis is most effective when applied in combination with 0.5 lbs ai/A of
atrazine.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Can be applied to field corn, seed corn, popcorn, and sweet corn. Check with seed supplier for information on
tolerance prior to use on popcorn, sweet corn, or inbreds grown for seed production.
в– в– Apply when broadleaf weeds are less than 6 inches tall. For most grass species, grasses should be less than 3
inches tall at time of application.
в– в– Apply broadcast up to the V8 stage of field corn.
в– в– Apply with MSO (1% v/v, minimum of 1.25 pt/A) plus either UAN (1.5 qt/A) or AMS (1.5 lb/A).
в– в– Apply in a minimum spray volume of 10 gpa, and apply in 15 to 20 gpa in dense weed populations or under adverse
environmental conditions. Use nozzles and pressure that result in medium spray droplets, and increase application
volume when using nozzles that produce coarse spray droplets. Flat fan nozzles of 80 or 110 degrees will provide
optimum postemergence spray coverage.
в– в– Laudis should not be relied upon to provide complete control of grasses, but can control small (less than 3-inch)
grasses that escape preemergence herbicides.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
Herbicide
Formulation
Product Rate Range
Nicosulfuron (active ingredient)
Accent Q
54.5WDG
0.9 oz
NIC-IT
2L
2 oz
в– в– These products contain nicosulfuron, a translocated sulfonylurea herbicide. Accent Q contains nicosulfuron plus
isoxadifen, a safener to reduce the risk of corn injury. Nicosulfuron controls annual and perennial grasses and a few
annual broadleaf weeds. Does not control crabgrass.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Accent Q and NIC-IT are labeled for use on field corn, popcorn, seed corn, and some sweet corn hybrids grown for
processing and fresh market. Growers should contact seed suppliers for recommendations and information on hybrid tolerance, and use of soil-applied organophosphate insecticides, prior to application to popcorn or seed corn.
Accent and NIC-IT can be used on High Lysine, Waxy, White or other Food Grade hybrids.
в– в– Can be applied broadcast or as a directed spray to field corn that is up to 20 inches tall or up to 6 collars (whichever occurs first). Apply as a directed spray when corn is 20 to 36 inches tall. Do not apply to corn that is at or past the
10-collar stage or more than 36 inches tall. Best results occur occur when corn is less than 12 inches tall and weeds
are small.
в– в– Can be applied broadcast to seed corn that is less than 20 inches tall or up to 5 collars (whichever occurs first).
в– в– For best results, apply with COC (1 gallon/100 gallons spray) plus UAN (2 to 4 quarts/A) or AMS (2 to 4 lbs/A). Substituting a MSO for COC can improve control under drought-stressed conditions. NIS (1 to 2 qts/100 gallons spray)
can be used instead of crop oil if required in a mixture with another herbicide.
в– в– Apply in a spray volume of at least 10 gpa with a pressure of 20 to 40 psi. Increase volume to at least 15 gpa in
heavy weed pressure. Avoid spraying excessive amounts of herbicide directly into the corn whorl.
■■Apply when grasses are at the following heights: foxtails and fall panicum — 2 to 4 inches; quackgrass — 4 to 10
inches; shattercane and seedling johnsongrass — 4 to 12 inches; rhizome johnsongrass — 8 to 18 inches.
в– в– Control of yellow and green foxtail may be reduced in mixture with some broadleaf herbicides. Consult the label for
spray additive recommendations when mixing with broadleaf herbicides, and follow the most restrictive label with
55
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate
NorthStar
47DF
5 oz
2.5 - 5 oz
в– в– NorthStar is a premix of primisulfuron (Beacon) plus dicamba (Banvel) for control of annual broadleaf weeds and
suppression or control of annual and perennial grasses. NorthStar will suppress a number of perennial broadleaf
weeds. See Beacon and dicamba descriptions for more information and precautions on use.
в– в– Site of action: group 2 (primisulfuron), group 4 (dicamba). See pages 14-15.
в– в– Can be applied broadcast or directed to field corn that is between 4 and 20 inches tall. Apply using drop nozzles
when corn is 20 inches (V6) up to 36 inches tall or 15 days before tassel emergence, whichever occurs first.
в– в– For seed corn inbreds, apply as a directed spray using drop nozzles when corn is between 10 and 36 inches tall or
15 days before tassel emergence, whichever occurs first. Inbred lines should be thoroughly tested for sensitivity to
NorthStar before treating large acreages.
в– в– Apply with NIS (0.25% v/v) or COC (1 to 4 pints/A), but do not use COC if corn is more than 12 inches tall. UAN (2 to
4 qts/A) or AMS (2 to 4 lbs/A) may also be added.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– When mixing with glyphosate, add AMS if the glyphosate contains adjuvants. Otherwise, add adjuvants specified
on the glyphosate product label.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Peak
57DF
0.25 - 0.5 oz
0.25 - 0.5 oz
в– в– Peak (prosulfuron) can be mixed with other broadleaf herbicides to improve control of emerged weeds and provide
residual control of burcucumber and other weeds in field corn.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Peak can be applied to corn up to 30 inches tall, but should be applied as a directed spray using drop nozzles
when corn is past the 6-collar stage or more than 20 inches tall.
в– в– When mixing Peak with a herbicide that contains a fully loaded adjuvant system (e.g. Touchdown Total), no additional adjuvant is needed. All other herbicide mixtures should be applied with COC (1% v/v).
в– в– Check label for recrop information prior to use. Recrop to soybeans and other crops varies with rate applied,
whether mixed with Spirit, area of the state, and soil pH. The recrop interval for soybeans can be 18 months for
some rates and mixtures.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Permit/Sandea/Halomax
75DF
2/3 to 1 1/3 oz
Not addressed on label
в– в– These products contain halosulfuron, is a translocated sulfonylurea herbicide that controls yellow nutsedge and
annual broadleaf weeds, including velvetleaf, ragweeds, cocklebur, and redroot pigweed. Halosulfuron is weak on
lambsquarters and annual morningglory. A combination of halosulfuron plus dicamba will improve control of these
weeds and control or suppress perennial broadleaf weeds. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply when field corn is in the spike through layby stage and most annual weeds are 1 to 6 inches tall for best
results. When corn is more than 24 inches tall, mixtures of halosulfuron with other postemergence corn herbicides
Corn
regard to maximum corn size at the time of application.
в– в– Control may be reduced if applied during conditions of drought stress, abnormally hot or cold weather, when daytime temperatures do not exceed 50 degrees, or following periods of large day/night temperature fluctuations.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
56
Corn
Corn: Postemergence Herbicides — Systemic
should be applied with drop nozzles to ensure weed coverage and avoid spraying directly into the whorl. Follow
the most restrictive label with regard to maximum corn size when m
В­ ixing with other herbicides..
в– в– For control of yellow nutsedge, apply 1 to 1 1/3 ounces/A when nutsedge is 4 to 12 inches tall. Dense populations of
nutsedge may require a second application.
в– в– Apply in a minimum spray volume of 10 gpa with NIS (1 to 2 quarts/100 gallons) or COC (1 gallon/100 gallons). Include UAN (2 to 4 quarts/A) or AMS (2 to 4 lbs/A) when velvetleaf or redroot pigweed is present.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Realm Q
38.75WDG
4 oz
4 oz
в– в– Realm Q is a premix of rimsulfuron (Resolve) and mesotrione (Callisto). It also contains a safener, isoxadifen, that
reduces risk of corn injury and broadens the application window, compared with other rimsulfuron products.
в– в– Realm Q controls or suppresses small annual grass (1 to 2 inches) and broadleaf (less than 5 inches) weeds, and
provides limited residual control. Can be mixed with glyphosate (glyphosate-resistant corn), Liberty (LibertyLink
corn), and other herbicides to broaden the spectrum of control, or for control of larger weeds, or to extend residual
control.
в– в– Site of action: group 2 (rimsulfuron); group 27 (mesotrione). See pages 14-15.
в– в– Can be applied broadcast to field corn up to 20 inches tall and prior to the 7-collar stage (whichever is more restrictive).
в– в– The preferred adjuvant system for Realm Q is COC or MSO (1% v/v) plus UAN (2 qt/A) or AMS (2 lb/A). NIS can be
used instead of COC/MSO. Do not use spray additives that adjust the spray solution pH below 5 or above 9 as
rapid product degradation can occur.
в– в– Use a minimum spray volume of of 15 gpa for best performance. Volume of 10 gpa can be used for light, scattered
stands of weeds. To minimize drift, apply using nozzles that deliver coarse spray or larger spray droplets.
в– в– When applied in a tank-mix with a glyphosate that contains a built-in adjuvant, ensure the total adjuvant load is
equivalent to the recommendations on the Realm Q label.
в– в– Do not mix with Basagran. See label and Table 10 for information about possible interactions between this herbicide
and soil-applied/foliar insecticides.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Resolve Q
22.4 WDG
1.25 oz
1.25 oz
Harrow
75 DF
0.33 oz
0.33 oz
в– в– Resolve Q and Harrow are premixes of rimsulfuron and thifensulfuron. Resolve Q also contains a safener, isoxadifen, that reduces risk of corn injury and broadens the application window, compared with other rimsulfuron products.
в– в– Controls or suppresses small (1 to 2 inch) annual grass and broadleaf weeds, including foxtails, lambsquarters, and
pigweed. When mixed with glyphosate in postemergence treatments to glyphosate-resistant corn, Resolve/Harrow
provides residual control of annual grasses and some small-seeded broadleaf weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Resolve Q can be applied broadcast to field corn with up to 6 collars, or up to 20 inches tall (whichever is more
restrictive). Harrow can be applied to corn in the spike to 2-collar stage; do not apply to corn over 6 inches tall.
в– в– Resolve Q should be applied with NIS (0.25% v/v) plus UAN (2 qt/A) or AMS (2 lb/A). Harrow should be applied with
COC (1% v/v) or NIS (0.25% v/v) plus UAN (2 qt/A) or AMS (2 lb/A). No additional adjuvants are needed when applying with Liberty or a glyphosate product that contains surfactant.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
57
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Solstice
4L
2.5 - 3.15 oz
Not addressed on label
в– в– Solstice is a premix of fluthiacet-methyl (Cadet) and mesotrione (Callisto) for control of most annual broadleaf weeds
less than 5 inches tall. Mix with atrazine for improved control of ragweeds or larger weeds.
в– в– Site of action: group 14 (fluthiacet); group 27 (mesotrione). See pages 14-15.
в– в– Can be applied to field and seed corn up to 30 inches tall, or the V8 stage, whichever occurs first. Consult seed
company for recommendations before using on inbred lines.
в– в– Apply with COC (1% v/v) or NIS (0.25% v/v) plus UAN (2.5% v/v) or AMS (8.5 lb/100 gallons). COC is the preferred
adjuvant. Do not apply with MSO or MSO blends. Do not apply in a mixture with emulsifiable concentrate grass
herbicides.
в– в– Apply in a spray volume of 10-30 gpa, and minimum of 15 gpa in dense foliage. Use spray nozzles that provide medium droplet size, and pressure of 35-40 psi at the nozzle. Flat fan nozzles are recommended for optimum coverage.
в– в– Solstice can cause bleaching and speckling of leaves, which is typically short-lived Spray boom should be kept a
minimum of 18 inches above the crop canopy to ensure uniform spray distribution and to avoid concentrating spray
in corn whorls.
в– в– See label and Table 10 for information about possible interactions between Solstice and insecticides.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Spirit
57DF
1 oz (1 packet per 4 acres)
0.75 - 1 oz
в– в– Spirit is a premix of prosulfuron (Peak) plus primisulfuron (Beacon), translocated sulfonylurea herbicides. Broadleaf
weed control is similar to Beacon, although Spirit is more effective on a few broadleaf weeds. Mixing with dicamba,
2,4-D, or bromoxynil will improve annual weed control. Most effective control/suppression of perennial broadleaf
weeds will occur when mixed with 2,4-D or dicamba. Spirit is weak on annual morningglories and yellow nutsedge.
Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Follow these guidelines to avoid carryover of Spirit to subsequent crops: 1) Avoid use where soil pH is greater than
7.8. If used where soil pH is greater than 7.8, plant only field corn or small grains the following year; 2) where less
than one inch of rain occurs within one month of application, or less than 12 inches of rain occurs within 5 months
after application, plant only corn, small grains, or STS soybeans the following year ; 2) north of Interstate 80, do not
plant soybeans within 18 months of application; 3) south of I-80, soybeans can be planted 10 months after application where soil pH is less than 7.8; and 4) do not apply after June 30. See label for guidelines on rotation to other
crops.
в– в– Apply broadcast or directed when field corn is 4 to 24 inches tall. To avoid injury and improve spray coverage on
weeds, apply as a directed spray using drop nozzles when corn is more than 20 inches tall.
в– в– For seed corn inbreds, Spirit can be applied broadcast when corn is between 4 and 20 inches tall, or until the 6-collar stage, whichever occur first. Use drop nozzles when seed corn inbreds are 20 to 24 inches tall and before tassel emergence. Inbred lines should be thoroughly tested for sensitivity to Spirit before treating large acreages.
Corn
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Shotgun
3.25L
2 - 3 pints
Not addressed on label
в– в– Shotgun is a premix of atrazine plus 2,4-D for postemergence control of many broadleaf weeds in corn.
в– в– Site of action: group 5 (atrazine), group 4 (2,4-D). See pages 14-15.
в– в– Apply broadcast in a minimum spray volume of 10 gpa when corn is spike to 8 inches tall, and as a directed spray
when corn is 8 to 12 inches tall. Treated corn may be brittle and subject to breakage by wind during the 2 weeks
following application.
в– в– Follow precautions to prevent drift and volatility of 2,4-D, which will injure nearby broadleaf plants. Volatility is
more likely at air temperatures greater than 85 degrees.
58
Corn
Corn: Postemergence Herbicides — Systemic
в– в– Apply in a minimum spray volume of 10 gpa. Increasing the volume to at least 20 gpa can improve control in dense
weed infestations.
в– в– Apply with COC (1 to 4 pints/A) or NIS (1 to 2 quarts/100 gallons). UAN (2 to 4 quarts/A) or AMS (2 lbs/A) may be
added to improve control of velvetleaf and other weeds. COC is generally more effective than NIS. Use of a MSO
(Meth Oil, Priority MSO, Sun-It II, for example) may improve control when weeds are large or drought-stressed.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Starane
1.5L
2/3 pt
Not addressed on label
в– в– Starane (fluroxypyr) is a translocated herbicide that controls hemp dogbane, common ragweed and a few other
broadleaf weeds. Due to a relatively narrow spectrum of activity, Starane should be mixed with other herbicides to
improve control of specific problem weeds.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply broadcast up to the V5 stage of field corn and when weeds are less than 8 inches tall. Applications when
corn is past the V5 stage should be made as a directed spray using drop nozzles.
в– в– Crop injury, including stem curvature, stunting, and brace root injury can occur with some corn hybrids when Starane is applied as a broadcast treatment. Hybrids susceptible to phenoxy injury may also be susceptible to injury
from Starane.
в– в– When mixing with other herbicides, use adjuvants specified on the label of the partner herbicides.
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Status
56 WDG
2.5 - 10 oz
2.5 - 5 oz
в– в– Status is a premix of dicamba plus diflufenzopyr plus a safener, for control of most annual broadleaf weeds in corn.
Addition of the safener results in reduced risk of injury to corn, compared with other dicamba products. Status can
be weak on velvetleaf, although it is more effective than dicamba alone.
в– в– Site of action: group 4 (dicamba), group 19 (diflufenzopyr). See pages 14-15.
в– в– Status can control or suppress small annual grasses that have escaped premergence herbicide treatments. Effectiveness on grasses is variable, and can be reduced under dry conditions.
в– в– Status is generally more effective than other dicamba products on perennial broadleaf weeds, and has provided
excellent control of Canada thistle and hedge bindweed in OSU research.
в– в– Apply when corn is 4 to 36 inches tall, or from V2 to V10. The 5 oz rate should be used when Status is applied postemergence following preemergence herbicides. The 2.5 oz rate can be used to improve control in mixtures with
glyphosate, Lightning, or Liberty, but rate should be increased to 5 oz where weeds are resistant to any of these
herbicides.
в– в– Status can be applied with NIS (0.25% v/v), COC (1 to 2 pt/A), or a methylated seed soil (1 to 2 pt/A) plus UAN (1.25%
v/v) or AMS (5 to 17 lbs/100 gallons). To avoid mixing problems, add Status to spray tank first, and make sure it is
fully suspended in water before adding AMS.
в– в– Take precautions to avoid contact of Status with sensitive plants via drift or volatility. Exposure of soybeans to
status via sprayer contamination or spray particle drift will result in more severe injury compared to other dicamba
products. Thoroughly clean spray equipment, including tank, hoses, and screens, to make sure it is free of Status
prior to using the same equipment in soybeans.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
59
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Stinger
3L
1/4 - 2/3 pt
Not addressed on label
в– в– Stinger (clopyralid) is a translocated herbicide that controls ragweeds, cocklebur, jimsonweed, and Canada thistle.
Controls or suppresses Jerusalem artichoke and suppresses sowthistle.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply after corn emergence until corn is 24 inches tall, and us a spray volume of at least 10 gallons per acre.
в– в– For annual weed and Jerusalem artichoke control, apply 1/4 to 1/2 pint when weeds have 5 or fewer leaves.
в– в– For Canada thistle control, apply 1/3 to 2/3 pint when thistles are at least 4 inches tall or across, but before the bud
stage. The higher rate provides more complete plant kill and better control of dense patches. Do not cultivate prior
to or for 14 to 20 days following application. Although control of thistle with Stinger during the season of application
may appear similar to that from other corn herbicides, Stinger provides more complete kill of the entire plant (at a
greater cost).
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
WideMatch
1.5L
1.3 pts
Not addressed on label
в– в– WideMatch is a premix of clopyralid (Stinger) plus fluroxypyr (Starane) for control of broadleaf weeds in corn, including hemp dogbane, ragweeds, Canada thistle, marestail, and cocklebur.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply broadcast up to the V5 stage of field corn and when weeds are less than 8 inches tall. Applications when
corn is past the V5 stage should be made as a directed spray using drop nozzles.
в– в– Crop injury, including stem curvature, stunting, and brace root injury can occur with some corn hybrids when WideMatch is applied as a broadcast treatment. Hybrids susceptible to phenoxy injury may also be susceptible to injury
from WideMatch.
в– в– For most effective Canada thistle control, apply after the majority of the basal leaves have emerged and before bud
stage.
Corn
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Steadfast Q
37.7 WDG
1.5 oz
Not addressed on label
в– в– Steadfast Q is a 2:1 premix of nicosulfuron (Accent) and rimsulfuron , translocated sulfonylurea herbicides, that
controls annual and perennial grasses, including foxtails, fall panicum, quackgrass, and shattercane. Will control
large crabgrass up to one inch tall. Controls small annual morningglory, pigweed, Pennsylvania smartweed, and
sunflower. Steadfast Q contains isoaxadifen, a safener that reduces the risk of crop injury.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Can be applied broadcast or as a directed spray to field corn that is up to 20 inches tall or up to 6 collars (whichever comes first). Best overall performance will occur when applied to corn less than 12 inches tall. Do not apply to
seed corn seed inbreds.
в– в– For best results, apply with COC (1 gallon/100 gallons spray) plus UAN (28% - 2 quarts/A) or AMS (2 lbs/A). Substituting a MSO (Meth Oil, Priority MSO, Sun-It II, for example) for COC can improve control under drought-stressed
conditions. NIS (1 to 2 qts/100 gallons spray) can be used instead of crop oil if required in a mixture with another
herbicide, but grass control may be reduced.
в– в– Apply in a spray volume of at least 15 gpa with a pressure of 20 to 40 psi. Avoid spraying excessive amounts of
herbicide directly into the corn whorl.
■■Apply when grasses are at the following heights: foxtails, fall panicum, and barnyardgrass — up to 4 inches; quackgrass — 4 to 8 inches; shattercane — up to 6 inches; seedling johnsongrass — up to 8 inches.
в– в– Control may be reduced if applied during conditions of drought stress, abnormally hot or cold weather, when nighttime temperatures are less than 40 degrees, or following periods of large day/night temperature fluctuations.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
60
Corn
Corn: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Yukon
67.5WG
4 - 8 oz
2 - 8 oz
в– в– Yukon is a premix of halosulfuron (Permit) plus dicamba for control of most annual broadleaf weeds and yellow
nutsedge. Yukon will also suppress/control some perennial broadleaf weeds, primarily during the growing season
of application.
в– в– Site of action: group 2 (halosulfuron); group 4 (dicamba). See pages 14-15.
в– в– Can be applied broadcast or with drop nozzles from the spike stage through 36 inch-tall corn. Weeds should generally be less than 6 inches tall for best results. Use a rate of 6 to 8 oz for yellow nutsedge control.
в– в– Apply with NIS (1 to 2 quarts/100 gallons) or COC (1 gallon/100 gallons). COC may cause injury at the higher Yukon
rates. UAN (28% UAN, etc - 2 to 4 quarts/A) or AMS (2 to 4 lbs/A) can be added to improve control of certain weeds
or if required for another herbicide in the spray mix. Apply in a spray volume of at least 10 gpa.
в– в– Most of the precautions and restrictions on use of Permit and dicamba apply to Yukon also. See Permit and dicamba descriptions for more information.
в– в– When mixing with glyphosate, add NIS at 0.25% v/v if glyphosate product used does not contain adjuvants. Use of
AMS at 8.5 - 17 lb/100 gal is required. When mixing with Liberty, the addition of AMS is required. (but not NIS).
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
2,4-D LV Ester
Various
0.17 - 0.25 lb ai/A
Not addressed on label
2,4-D Amine
Various
0.34 - 0.5 lb ai/A
в– в– Site of action: group 4 (see pages 14-15).
в– в– Controls many annual broadleaf weeds, including ragweeds, cocklebur, lambsquarters, and pigweed. Will control or
suppress perennial broadleaf weeds, especially when applied with Beacon, Exceed, Spirit, or Permit.
в– в– For best results, apply when weeds are small.
в– в– If corn is more than 8 inches tall, use drop nozzles to reduce the risk of crop injury. Do not apply from the tasseling
stage to the dough stage.
в– в– Use precautions to prevent drift. The ester forms of 2,4-D can volatilize and injure nearby susceptible plants, including soybeans and vegetable crops. Amine formulations are less volatile than ester formulations, and should generally be used for postemergence applications in corn.
в– в– Injury may result when applied to corn growing rapidly under high temperatures and high humidity. Corn may be
brittle for 7 to 10 days after application, and is susceptible to stalk breakage from high winds or cultivation.
61
LibertyLink Corn — Postemergence Herbicides
Formulation
2.34L
Product Rate Range
22 oz
в– в– Liberty (glufosinate) is a contact, broad-spectrum herbicide for postemergence use only on LibertyLink (glufosinateresistant) corn.
в– в– Site of action: group 10 (see pages 14-15).
в– в– Liberty controls many annual grass and broadleaf weeds up to 3 to 6 inches tall when applied at a rate of 22 oz
per acre. Mixing with atrazine improves control of many weeds, including pigweeds, waterhemp, velvetleaf, annual morningglories, and lambsquarters, and provides several weeks of residual control. Maximum total amount of
Liberty that can be applied per season (burndown + POST) is 44 oz.
в– в– OSU and Purdue University research indicates that Liberty is most effective in a combined preemergence plus
postemergence program, where the preemergence herbicide will provide control of grass and broadleaf weeds for
several weeks to a month after corn planting. Postemergence applications of Liberty in this program should include
atrazine, Capreno, or Laudis where possible. Liberty is weak on yellow foxtail, barnyardgrass, and lambsquarters,
and the other PRE or POST herbicides used with Liberty should provide substantial control of these weeds.
в– в– Maximum height for grass weeds at the 22 oz/A rate: barnyardgrass, crabgrass, yellow foxtail, fall panicum - 3 inches; woolly cupgrass, shattercane, and green, giant, and robust foxtails - 6 inches; volunteer corn - 10 inches. Yellow
foxtail and crabgrass should be treated prior to tiller initiation for best results. Liberty is most effective on volunteer
corn (including glyphosate-resistant) that is 6 to 12 inches tall.
в– в– Maximum height for broadleaf weeds at the 22 oz/A rate: velvetleaf, pigweeds - 3 inches; lambsquarters, waterhemp - 4 inches; burcucumber, cocklebur, annual morningglories, black nightshade, ragweeds, and Pennsylvania
smartweed - 6 inches.
в– в– Liberty plus atrazine (1 lb ai/A) will control or suppress some perennial weeds, including dandelion, Canada thistle,
Jerusalem artichoke, and wirestem muhly. Liberty has activity on above-ground growth only, so regrowth of perennials may occur and retreatment may be necessary.
в– в– Apply with AMS at the rate of 3 lbs/A, or 17 lbs/100 gallons. When air temperatures are above 85 degrees, the rate
can be reduced to 1.5 lbs/A, or 8.5 lbs/100 gallons, to reduce the risk of leaf burn. Applying with surfactants or crop
oils may increase the risk of crop injury.
в– в– Apply broadcast from corn emergence through the V7 stage (7 collars), and as a directed spray up to 36-inch corn.
в– в– Apply in a minimum spray volume of 15 gpa. Use a volume of 20 to 40 gpa in dense weed/crop canopies. Liberty
should be applied with a nozzle type and spray pressure that results in medium spray droplets (250 to 350 microns).
в– в– Liberty is most effective when applied under warm, sunny conditions. Effectiveness may be reduced if applied
when heavy dew, fog and mist/rain are present, or if weeds are under stress due to drought, cool temperatures,
or extended periods of cloudiness. To avoid reduced weed control, apply between dawn and two hours before
sunset.
Corn
Herbicide
Liberty 280SL
62
Corn
Glyphosate-Resistant Corn — Postemergence Herbicides
Herbicide
Formulation
Product Rate Tange
Callisto GT
4.18L
2 pt
в– в– Callisto GT is a premix of glyphosate and mesotrione (Callisto) that controls emerged grass and broadleaf weeds in
glyphosate-resistant corn, and provides residual control of broadleaf weeds. See descriptions of glyphosate and
Callisto for more information on these herbicides.
в– в– Site of action: group 9 (glyphosate), group 27 (mesotrione). See pages 14-15.
в– в– Use rate provides the equivalent of 3 oz of Callisto and 0.85 lb ae glyphosate.
в– в– Apply before corn exceeds 30 inches in height, and prior to the V8 stage.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
в– в– Apply with NIS (0.25 to 0.5% v/v) and AMS (8.5 to 17 lbs/100 gallons). NIS can be replaced with COC (1% v/v) but
risk of crop injury increases. Do not use MSO or MSO-based adjuvants.
Herbicide
Formulation
Expert4.88L
в– в– Expert is a premix of glyphosate, s-metolachlor (Dual II Magnum), and atrazine that can be applied early postemergence to glyphosate-resistant corn. See descriptions of glyphosate and metolachlor/s-metolachlor plus atrazine for
more information on these herbicides.
в– в– Site of action: group 9 (glyphosate), group 5 (atrazine), group 15 (s-metolachlor). See pages 14-15.
в– в– Use rates provide the equivalent of 0.4 to 0.75 lbs of glyphosate acid and 1.75 to 2.6 quarts/A of Bicep II Magnum.
Use rate ranges from 2.5 to 3.75 qts/A on coarse-textured soils with less than 3% organic matter, and from 3 to 3.75
on all other soils.
в– в– Apply before corn exceeds 12 inches in height.
в– в– Use water as the spray carrier for postemergence applications. Do not mix other products with Expert when applying to emerged corn. Can cause minor corn leaf burn.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various - see Table 24
0.56 - 1.12 lb ae/A
в– в– Glyphosate is a translocated herbicide that controls emerged annual and perennial grass and broadleaf weeds.
Table 24 contains a list of currently available glyphosate products. Variations in the formulation may result in difп»їferences in product rate and adjuvant recommendations, and specified rainfast intervals. Users should consult labels
and local product use guides for more specific information.
в– в– Apply postemergence only to glyphosate-resistant corn hybrids (Roundup Ready, Agrisure GT, etc).
в– в– Site of action: group 9 (see pages 14-15).
в– в– The general recommendation on most labels for the initial postemergence glyphosate application is a rate of 0.56
to 0.75 lbs of glyphosate acid per acre (lbs ae/A) when weeds are less than 4 inches tall, or before weeds become
competitive with the crop (see Table 24 for product rates). Rates should be increased to 1.1 lbs ae/A where weeds
are more than 6 inches tall. Multiple postemergence applications of glyphosate are allowed. The maximim rate
per application is 1.1 lbs ae/A of glyphosate and the total amount that can be applied postemergence in one season
should not exceed 2.25 lbs ae/A. There are exceptions to this depending upon the glyphosate product used and
the type of glyphosate-resistant corn planted, and in some situations the maximum rate and amount that can be applied may be lower. Consult seed supplier and glyphosate product label prior to use.
в– в– University research has shown that postemergence glyphosate treatments should be applied when weeds are no
more than 2 to 4 inches tall in order to avoid corn yield loss from early-season weed competition. Where preemergence herbicides are applied, there may be more flexibility in the timing of postemergence glyphosate treatments.
в– в– The following management practices are most effective for minimizing the risk of glyphosate resistance in weeds,
maintaining adequate weed control, and preserving maximum crop yield: 1) start weed free at planting through
63
Glyphosate-Resistant Corn — Postemergence Herbicides
в– в– в– в– в– в– в– в– Herbicide
Formulation
Product Rate Range
Halex GT
4.38L
3.6 - 4 pts
в– в– Halex GT is a premix of glyphosate, mesotrione (Callisto), and s-metolachlor (Dual II Magnum) for postemergence
use in glyphosate-resistant corn (Agrisure GT, Roundup Ready 2, etc). This product controls emerged grass and
broadleaf weeds, and provides approximately 4 weeks of residual weed control.
в– в– Site of action: group 9 (glyphosate); group 13 (mesotrione); group 15 (s-metolachlor). See pages 14-15.
в– в– Weeds should be less than 2 to 4 inches tall at the time of application to minimize risk of yield loss from early-season weed interference. Apply with atrazine if weeds are more than 4 inches tall, or where weeds are resistant to
glyphosate.
в– в– Apply to glyphosate-resistant corn up to 30 inches tall or the 8-leaf stage, whichever occurs first. When mixed with
atrazine, apply to corn up to 12 inches tall.
в– в– Apply with NIS (1 to 2 qts/100 gallons) and AMS (8.5 to 17 lbs/100 gallons), using water as the spray carrier.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
Corn
в– в– use of tillage or a preplant burndown herbicide application; 2) Apply preplant/preemergence herbicides at rates
that provide 4 to 6 weeks of residual weed control; 3) make the first postemergence glyphosate application when
weeds are less than about 4 inches tall; and 4) make a second postemergence glyphosate application about 3
weeks later as needed to control late-emerging weeds and weeds that were no completely killed by the initial application.
A total postemergence approach can be effective in glyphosate-resistant corn, but only when: 1) the field is weed
free at the time of crop planting through use of tillage or preplant burndown herbicides; 2) the postemergence
treatment is applied soon enough after planting to small weeds (less than 2 to 4 inches tall), in order to avoid yield
loss from weed interference; and 3) when the postemergence treatment includes not only glyphosate, but also
residual herbicides that will control later-emerging weeds for several weeks to a month.
For Roundup Ready Corn 2, most glyphosate products can be applied broadcast or as a directed spray using drop
nozzles from corn emergence through the 8-collar stage or until corn is 30 inches tall, whichever occurs first. When
corn is 24 to 30 inches tall, use of drop nozzles will generally improve spray coverage on weeds. Drop nozzles can
be used to apply glyphosate to Roundup Ready Corn 2 up to 48 inches tall, but should be adjusted to keep spray
out of corn whorls. Similar guidelines apply to the use of Touchdown on Agrisure GT corn. However, not all glyphosate products are labeled similarly with regard to use on Agrisure GT corn. Consult seed supplier and glyphosate
product label prior to use.
Glyphosate resistance has developed in populations of marestail, Palmer amaranth, waterhemp, and common and
giant ragweed in Ohio, Indiana, and Illinois, and some lambsquarters populations appear to have become less
sensitive to glyphosate. Consider use of a preemergence herbicide that provides residual control of these weeds,
and avoid use of herbicide programs consisting solely of multiple glyphosate applications. In fields with a history of
poor glyphosate performance on lambsquarters and giant and common ragweed, include another postemergence
herbicide (Status, Callisto, etc) with the glyphosate to improve control.
Control of perennial weeds will require higher rates than annual weeds. Application when perennials are in the bud
to bloom stage (or boot to seedhead for grasses) will provide the most complete control of the entire plant. Minimum size of various perennial weeds for most effective control through the growing season: quackgrass, Canada
thistle, wirestem muhly, and yellow nutsedge - 6 inches; field bindweed and common milkweed -12 inches; johnsongrass and hemp dogbane - 18 inches.
Apply in a spray volume of 5 to 20 gpa. Take precautions to reduce spray drift, since corn, soybeans, and other
sensitive crops are likely to be growing in areas surrounding treated fields. The risk of spray drift can be reduced
by using a volume of 15 to 20 gpa, selecting the appropriate nozzles, and reducing spray pressure.
64
Corn
Glyphosate-Resistant Corn — Postemergence Herbicides
Herbicide
Formulation
Sequence5.25L
в– в– Sequence is a premix of glyphosate plus s-metolachlor (Dual II Magnum) that can be applied postemergence to
glyphosate-resistant corn to provide control of emerged weeds and residual control of annual grasses, black nightshade, pigweed, Palmer amaranth, and waterhemp.
в– в– Apply 2.5 to 3.5 pints/A up to the V8 stage or 30-inch corn (broadcast), or up to 48 inches tall (with drop nozzles).
Avoid application into whorls of corn plants.
в– в– Add AMS (8.5 to 17 lbs/100 gallons) where concentration of Ca, Mg, and Mn in water exceeds 150 ppm, and to generally improve control of some weeds.
65
Corn: Harvest Aid
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
See labels.
в– в– Many glyphosate products can be applied as a preharvest treatment to control perennial and annual weeds in corn.
Application rate varies with glyphosate product, type of application (ground vs aerial), type of corn (glyphosateresistant corn vs other), and amount of glyphosate previously applied. Consult labels for specific recommendations.
в– в– Preharvest applications of glyphosate may provide a good opportunity to control perennial weeds, such as pokeweed, because their growth is undisturbed compared to postharvest applications.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Apply when grain moisture is 35 percent or less. Corn should be physiologically mature (black layer formed) with
maximum kernel fill complete. Apply at least 7 days before harvest.
в– в– Depending upon the glyphosate product, the label prohibits or recommends avoiding preharvest application to
corn grown for seed, due to the potential for a reduction in germination or vigor.
Herbicide
Formulation
Product Rate Range
Gramoxone SL
2L
1.2 - 2 pt
Parazone
3SL
0.8 - 1.3 pt
в– в– Gramoxone and Parazone (paraquat) may be used for drying weeds in field corn, seed corn, and popcorn just before harvest. Apply when corn is mature - after the black layer has formed at the base of the kernels.
в– в– Site of action: group 22 (see pages 14-15).
в– в– Mature cocklebur and lambsquarters are tolerant of paraquat and may not desiccate completely.
в– в– For aerial application, use a spray volume of 5 gallons per acre; for ground application, use 20 gallons per acre.
Add NIS (0.25% v/v) or COC (1% v/v).
в– в– Apply at least 7 days before harvest.
Corn
Herbicide
Formulation
Product Rate Range
Aim
2EC
1 - 2 oz
в– в– Aim (carfentrazone) can be applied prior to harvest of corn for dessication of velvetleaf, morningglory, pigweeds,
and other weeds. Apply at least 3 days before harvest when the crop is mature and grain has begun to dry down.
в– в– Site of action: group 14 (see pages 14-15).
в– в– The total amount of Aim that can be applied to small grains in one season, including postemergence and harvest
aid treatments, cannot exceed 2 oz/A. UAN or AMS can be added.
в– в– Use a spray volume that results in complete coverage of foliage. Apply with NIS (0.25% v/v) or a COC (1 to 2% v/v).
UAN or AMS may also be added.
66
Corn
Table 7. Grazing and Forage (Silage, Hay, etc.) Intervals for Herbicide-Treated Corn
This table is a guide for grazing and feeding herbicide-treated corn, and shows the time that should occur between herbicide
application and grazing or harvest for silage. For premixes or combinations not listed below, the minimum interval equals the longer
of the two intervals for each individual product in the mix. Always consult herbicide labels for specific limitations.
Herbicide
Grazing
Forage (silage, etc.)
2,4-D
7 days
7 days
Aim
None
None
Anthem
70
30
Anthem ATZ
70
60
Atrazine
60 days
60 days
Balance Flexx
None
None
Basagran
12 days
None
Beacon
30 days
45 days
Bestow
30 days
30 days
Bicep II Magnum/Cinch ATZ
30 days
30 days
Breakfree NXT/Breakfree NXT ATZ
21 days
21 days
Bromoxynil
30 days
30 days
Cadet
90 days
30 days
Callisto
Do not graze
45 days
Callisto GT
45 days
45 days
Callisto Xtra
Do not graze
60 days
Capreno
45 days
45 days
Corvus
45 days
45 days
Define
None
None
Degree Xtra
60 days
60 days
Dicamba
Past “milk” stage
Past “milk” stage
Dicamba+atrazine
Past “milk” stage
Past “milk” stage
Distinct
32 days
32 days
Dual II Magnum/Cinch
30 days
30 days
Expert
60 days
60 days
Fierce
None
None
FulTime NXT
21 days
21 days
Gramoxone SL (at planting)
None
None
Harness
21 days
21 days
Harness Xtra
60 days
60 days
Harrow
30 days
30 days
Hornet
85 days
45 days
Impact/Armezon
45 days
45 days
Instigate
45 days
45 days
Keystone NXT
21 days
21 days
Laddok
21 days
21 days
Laudis
45 days
45 days
67
Table 7. Grazing and Forage (Silage, Hay, etc.) Intervals for Herbicide-Treated Corn (continued)
Grazing
Forage (silage, etc.)
Liberty
70 days
60 days
Lumax/Lexar
45 days
45 days
Metribuzin
60 days
60 days
Nicosulfuron
30 days
30 days
Northstar
30 days
45 days
Outlook
60 days
60 days
Parallel
30 days
30 days
Peak
30 days
40 days
Pendimethalin
21 days
21 days
Permit/Sandea/Halomax/Permit Plus
30 days
30 days
Prequel
30 days
30 days
Princep/simazine
Do not graze
None
Python
85 days
85 days
Radius
None
None
Realm Q
45 days
45 days
Resolve Q/Crusher
30 days
30 days
Resource
28 days
28 days
Roundup WeatherMax, Glyphomax, other
glyphosates
50 days
50 days
Sharpen
80 days
80 days
Shotgun
21 days
21 days
Spirit
30 days
40 days
Stalwart C, Stalwart Xtra
30 days
30 days
Solstice
30 days
30 days
Starane
47 days
47 days
Status
32 days
32 days
Steadfast
30 days
30 day
SureStart/TripleFlex
45 days
45 days
Surpass NXT
21 days
21 days
Stinger
40 days
40 days
Touchdown
50 days
50 days
Valor
None
None
Verdict
80 days
80 days
Volley/Volley ATZ
21 days
21 days
WideMatch
47 days
47 days
Yukon
30 days and past “milk” stage
30 days and past “milk” stage
Zemax
45 days
45 days
Zidua
No restriction
No restriction
Corn
Herbicide
68
Table 8. Rainfast Intervals, Spray Additives, and Crop Size for Postemergence Corn Herbicides
Corn
This table shows the required time interval between herbicide application and rainfall and summarizes label recommendations for
spray additives and maximum crop stage. Check herbicide labels for additive rates. Information in this table applies to field corn only.
Herbicide
2,4-D Amine
2,4-D Ester
Accent Q, NIC-IT
Aim
Rainfast
Interval
(hours)
6-8
2-3
4
1
Atrazine
Basagran
Beacon
Bestow
Bromoxynil
Bromoxynil+atrazine
Cadet
Callisto
Callisto GT
Callisto Xtra
Capreno
Dicamba
2
8
4
4
1
2
4
1
1
6-8
Dicamba/atrazine
6-8
Halex GT
Harrow
Hornet
2
4
2
Impact/Armezon
1
Laddok
Laudis
Laudis + atrazine
Liberty
Northstar
8
1
2
4
4
Peak
Permit/Sandea/
Halomax
Permit Plus
Realm Q
Resolve Q
Resource
Shotgun
Solstice
Spirit
4
4
4
4
4
1
6
1
4
Starane
Status
Steadfast Q
1
4
4
Stinger
WideMatch
Yukon
Zemax
6-8
6
4
1
Spray additives/Maximum Crop Size
No additives. Broadcast up to 8-inch corn; directed spray before tassel stage.
No additives. Broadcast up to 8-inch corn; directed spray before tassel stage.
MSO, COC or SURF (Addition of UAN or AMS is recommended). Broadcast up to 6 collars or 20-inch corn; directed spray
up to 10 collars or 36-inch field corn.
SURF. AMS or UAN may be added if required by tank-mix partner. Do not use COC or tank-mix with EC formulations of
other crop protection chemicals except as specifically directed by label. Apply up to 8-collar corn.
MSO or COC. Apply before corn is 12 inches tall.
COC, MSO, UAN, or AMS or COC or MSO + UAN or AMS, depending on weed species present.
MSO, COC, or SURF (UAN or AMS may be added). Broadcast 4 to 20-inch corn; directed spray before tassel emergence.
NIS + UAN or AMS. Broadcast up to 12 inches or 5-collar stage.
No additives. Apply before tassel emergence.
No additives. Apply before corn is 12 inches tall.
NIS, COC, or MSO. UAN or AMS can be added. Preplant up to 48 inches tall, and before tassel emergence.
COC + UAN or AMS. Apply up to 30-inch or 8-leaf corn.
NIS + AMS. COC can be used instead of NIS but increases risk of crop injury. Broadcast up to 30-inch or V8 corn.
COC or NIS + UAN or AMS. Apply up to 12-inch corn.
COC + UAN or AMS. Apply broadcast from V1 to V6 corn; directed spray up to V7 corn.
Add UAN if velvetleaf is present. SURF, COC, or UAN may be added under dry conditions. Do not apply with COC when
corn height exceeds 5 inches. Broadcast up to 5th-leaf stage or 8-inch corn; directed spray up to 36-inch corn.
Add UAN if velvetleaf is present. SURF, COC, or UAN may be added under dry conditions. Do not apply with COC when
corn height exceeds 5 inches. Apply broadcast up to 5-leaf stage or 8-inch corn.
SURF + AMS. Broadcast up to 30-inch or 8-leaf corn.
SURF, COC, or MSO plus UAN or AMS. Broadcast from spike to 2-collar stage, and not more than 6 inches tall.
SURF, COC, or MSO. UAN or AMS may be added under extremely dry conditions. Broadcast up to 20-inch corn or 6 collars; directed spray up to 36-inch corn.
MSO or COC + UAN or AMS. SURF can be used in combinations with other broadleaf herbicides. Apply broadcast or
directed up to 45 days before harvest.
MSO, COC, UAN, AMS, DASH, or combinations of these. Apply before corn is 12 inches tall.
MSO + UAN or AMS. Broadcast up to V8 corn.
COC + UAN or AMS. Broadcast up to 12-inch corn
AMS. Broadcast or directed up to 24-inch or V7 corn. Directed spray up to 36-inch corn.
SURF, COC or MSO up to 12-inch corn. Only SURF between 12 and 36-inch corn. UAN or AMS may be added. Broadcast 4
to 20-inch corn; directed spray up to 36-inch corn.
COC unless mixed with glyphosate. Broadcast up to V6 or 20-inch corn; directed spray up to 30 inches.
SURF, MSO, or COC. UAN or AMS may be added. Apply through layby stage of corn.
SURF or COC + UAN or AMS. Broadcast or directed from 1- to 5-collar stage.
SURF or COC + UAN or AMS. Broadcast or directed up to 20 inches and prior to the 7-collar stage.
NIS + UAN or AMS, unless mixed with a glyphosate product or Ignite. Broadcast up to 20-inch or 6 collar corn.
COC. UAN or AMS may be added to improve control of certain species. Apply up to the 10-leaf stage.
No additives. Apply before 12-inch corn.
COC or NIS + UAN or AMS. COC is preferred adjuvant. Do not use MSO. Up to V8 or 30-inch corn.
COC, MSO or SURF.UAN or AMS may be added. Broadcast 4 to 20-inch corn; directed spray up to 24-inch corn or after 6
collar corn.
An adjuvant can be used if required by tank-mix partner. Broadcast up to the V5 stage; directed spray after the V5 stage.
SURF, COC, or MSO + UAN or AMS. Broadcast from 4 to 36-inch corn (rates up to 5 oz/A)
COC, MSO, or SURF + UAN or AMS. COC or MSO is preferred over SURF. Broadcast up to and including 6 collars or 20inch corn
No additives. Up to 24-inch corn.
No additives. Broadcast up to the V5 stage; directed spray after the V5 stage.
SURF or COC. UAN or AMS may be added. Apply broadcast or directed up to 36-inch corn.
SURF or COC. Apply up to 30-inch or 8-leaf corn.
69
Table 9. Herbicides Labeled for Use on Field Corn, Seed Corn, Popcorn, and Sweet Corn
Field Corn
Field Corn Grown for Seed
Popcorn
Y
Y
Y
Y
Y
Y
Y
Y
Y5
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y5
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y5
Y5, 8
Y9
Y5
Y
Y5
Y
N
Y5, 7
N
Y
Y
2,
Y 5
Y
Y
Y5
Y5
Y
Y
Y5
Y5
Y
Y
N
Y
Y
N
Y5
Y5
N
Y3
Y
Y5
Y
N
Y5, 7
Y
Y
N
Y
Y
N
N
N
Y5
N
N
Y5
Y
Y5
Sweet Corn
Y
Y1, 5, 8
Y5, 8
Y
Y5
Y
N
Y
N
Y5, 7
N
Y
Y
Y2
Y
Y10
N
N
Y
Y
Y5
Y5
Y
Y
N
Y
Y
N
N
Y5
N
Y
Y
Y5
Y10
N
Y5, 7
Y
Y
N
Y
Y
N
N
N
N
N
N
N
Y5
Y5
Y5
Y
N
Y
N
N
N
Y
Y
N
Y
Y
N
N
Y
Y
N
N
Y
Y
N
Y
Y
N
N
Y5
N
Y
Y
Y5
Y
N
N
Y5
N
N
Y
Y5
N
N
N
N
N
N
N
N
Corn
2,4-D
Accent Q/NIC-IT
Aim
Anthem/Anthem ATZ
Atrazine
Balance Flexx
Basagran
Basis
Beacon
Bestow
Bicep II Magnum/Cinch ATZ
Breakfree NXT/Breakfree NXT ATZ
Bromoxynil
Cadet
Callisto, Callisto Xtra
Capreno
Corvus
Degree
Degree Xtra
Dicamba
Dicamba+atrazine
Dual II Magnum/Cinch
Expert
Fierce
FulTime NXT
Harness/Harness Xtra
Harrow
Hornet
Impact/Armezon
Instigate
Keystone NXT
Laddok
Laudis
Lumax/Lexar EZ
Metribuzin
Northstar
Outlook
Parallel/Parallel Plus
Peak
Pendimethalin
Permit/Sandea/Halomax
Permit Plus
Prequel
Princep/simazine
Python
Realm Q
Resolve Q/Crusher
Resource
Sharpen
70
Corn
Table 9. Herbicides Labeled for Use on Field Corn, Seed Corn, Popcorn, and Sweet Corn (continued)
Shotgun
Solstice
Spirit
Stalwart C/Stalwart Xtra
Starane
Status
Steadfast Q
Stinger
SureStart/TripleFlex
Surpass NXT
Valor
Verdict
Volley/Volley ATZ
Warrant
WideMatch
Yukon
Zemax
Zidua
Field Corn
Field Corn Grown for Seed
Popcorn
Sweet Corn
Y
Y
Y5
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
N
Y
5,
Y 7
Y
N
Y
N
Y5
N
Y
N
Y
Y
N
N
Y
Y
Y5
N
Y
5,
Y 7
Y
N
Y
N
N
N
Y
N
Y5
Y
N
N
N
Y10
Y5
N
Y
N
Y
Y
N
N
N
N
Y
N
N
Y
N
Y
N
Y
Y5
1Do not apply to any white popcorn inbred or hybrid unless approved by seed supplier.
2Do not apply prior to 3-leaf corn stage.
3Do not use on corn seed stock such as “Breeders,” “Foundation,” or “Increase.”
4Do not make postemergence application of Partner or Microtech to sweet corn.
5Check with seed supplier or chemical representative for sensitivity of inbreds/hybrids prior to use.
6Injury may occur on field corn hybrids with a Relative Maturity (RM) rating of less than 88 days or on waxy, Hi-Lysine, or food grade corn.
7Can be used if spray is directed using drop nozzles when seed corn is between 4 and 20 and 4 and 30 inches tall for Spirit and Exceed, respectively, when popcorn is be-
tween 10 and 24 and 10 and 30 inches tall for Spirit and Exceed respectively, and when seed corn and popcorn are between 10 and 36 and 10 and 48 inches tall for Northstar
and Beacon, respectively. All products must be applied before tassel emergence.
8Do not apply if corn is greater than 20 inches tall or exhibits 5 collars.
9Apply as directed spray only. Avoid herbicide application into the corn whorl.
10Yellow popcorn only.
71
Table 10. Herbicide and Soil Insecticide Use Precautions
Soil-applied Organophosphate Insecticides
Counter
20CR (in
furrow)
Counter
20CR
(banded)
Thimet/
phorate
Lorsban
Aztec
Fortress
Capture
LFR
Beacon
Do not use
NR
TI
TI
TI
TI
Y
Bestow
45 days
45 days
45 days
45 days
NR
NR
Y
NR
NR
See label
NR
See label
See label
Y
Callisto GT
Do not use
Do not use
Do no use
Do not use
See label
See label
Y
Capreno
Do not use
Do not use
Do not use
Do not use
Y
Do not use
Y
Crusher
60 days3
60 days3
NR
NR
Y
Y
Y
Corvus
Do not use
Do not use
Y
Y
Y
Y
Y
NR
NR
NR
NR
NR
NR
Y
Herbicide
Callisto, Callisto Xtra (POST)
Halex GT
Harrow (POST)
45 days
45 days
TI
TI
NR
NR
Y
Hornet (PRE)
Do not use
Do not use
Do not use
TI1
TI1
TI1
Y
Hornet (POST)
Do not use
Do not use
Do not use
TI
TI
TI
Y
Instigate (PRE)
Do not use
Do not use
Do not use
Do not use
Y
Y
Y
Instigate (POST)
Do not use
Do not use
TI
TI
Y
Y
Y
Lexar, Lumax EZ (POST)
NR
NR
TI
TI
TI
TI
Y
Nicosulfuron
Do not use
NR
TI
TI
Y
Y
Y
NorthStar
Do not use
NR
TI
TI
TI
TI
Y
Peak
Do not use
Do not use
TI
TI
TI
TI
Y
Permit/Sandea/Halomax
Y
Y
Y
Y
Y
Y
Y
Prequel
Do not use
TI
TI2
TI2
Y
Y
Y
Python
Do not use
Do not use
Do not use
TI1
TI1
TI1
Y
Realm Q
NR
NR
NR
NR
Y
Y
Y
60 days3
60 days3
Y
Resolve Q
Do not use
NR
NR
NR
Solstice
Do not use
Do not use
Do not use
Do not use
Y
Y
Y
Spirit
Do not use
NR
TI
TI
TI
TI
Y
Steadfast Q
Do not use
NR
NR
TI
Y
Y
Y
SureStart/TripleFLEX
Do not use
Do not use
Do not use
TI1
TI1
TI1
Y
Verdict, Sharpen
Do not use
Do not use
Do not use
Do not use
Y
Y
Y
Yukon
Y
Y
Y
Y
Y
Y
Y
Zemax (POST)
NR
NR
NR
NR
NR
NR
Y
1Apply the soil insecticide in a T-band or a band to reduce risk of crop injury.
2Do not use herbicide if soil insecticide is applied in furrow.
Herbicide may be used if soil insecticide is applied in a band, but temporary corn injury may still occur.
3Do not apply herbicide within 60 days of insecticide application.
Corn
This table is a guide to using herbicides on field corn where an organophosphate (OP) insecticide is used at planting. Do not mix
an OP insecticide with the herbicides shown below, as severe injury will occur. Read the herbicide label before applying OP insecticides postemergence when using any of these herbicides.
Definitions and Abbreviations:
Do not use = do not apply the herbicide if corn has been previously treated with soil insecticide.
NR = not recommended to apply the herbicide if corn has been previously treated with soil insecticide.
TI = Temporary injury may occur if the herbicide is applied to corn previously treated with soil insecticide.
Y = The herbicide can be used with nearly no risk of injury when applied to corn previously treated with soil insecticide.
72
Popcorn and Sweet Corn
Popcorn and Sweet Corn Weed Management
Weed management in popcorn and sweet corn is
similar to field corn in many respects. However, there
are a few important points to keep in mind when planning a weed management strategy for these specialty
crops. First, not every product labeled in field corn is
labeled in popcorn or sweet corn. Second, the sensitivity of popcorn and sweet corn inbreds and hybrids to
herbicides varies. Popcorn and sweet corn inbreds and
hybrids are generally selected based on their performance, but the selection can determine which herbicides can be used.
White popcorn lines are often more sensitive to
herbicides than yellow corn lines. Tolerance of sweet
corn to herbicides has been intensively studied, but the
sensitivity of the many new varieties introduced every
year is often uncertain. Labels for several new herbicides contain statements that limit the herbicide manufacturer's liability should sweet corn be damaged. Many
sweet corn varieties are sensitive to mesotrione and
sulfonyl urea herbicides. A few varieties are sensitive
to Laudis while nearly all varieties tolerate Impact. For
more information on sweet corn varietal response to
herbicides visit the web sites listed below. It is always a
good idea to address this issue with your seed supplier
before selecting herbicides to use in popcorn or sweet
corn. Finally, most popcorn and some sweet corn is
grown under contract, and seed company contracts may
specify herbicide programs to be used on their varieties.
в– в– Ranking of sweet corn variety tolerance to nicosulfuron and Callisto:
http://ipcm.wisc.edu/WCMNews/tabid/53/EntryId/656/Sweet-Corn-Tolerance-Results-from-2008.aspx
http://ag.udel.edu/rec/WeedScience/Research_reports/Sweet%20Corn%20Hybrid%20Tolerance%20Rating%202007.pdf
в– в– Response of sweet corn varieties to Impact and
Laudis:
http://ag.udel.edu/rec/WeedScience/Research_reports/Sweet_Corn_Tolerance_laudis_impact_07.pdf
The number of broad-spectrum postemergence
herbicides labeled for popcorn and sweet corn is somewhat limited. Annual grasses should be controlled with
preemergence herbicides, such as acetochlor (Degree,
Harness, Surpass, and Topnotch), metolachlor, (Dual II
Magnum), and dimethenamid-P (Outlook). Accent can
be applied for postemergence grass control in popcorn,
but it cannot be used on some hybrids and inbreds. Impact is much less likely to cause injury to popcorn than
Accent, and it can be applied postemergence for control
of small grasses and many broadleaf weeds. Shattercane, johnsongrass, and quackgrass can be particularly
difficult to manage in these speciality crops. Fields infested with these weeds should probably not be planted
to popcorn or sweet corn.
Many of the broadleaf herbicides labeled for field
corn can also be used in popcorn and sweet corn. Atrazine is probably the most commonly used herbicide,
and has activity on many broadleaf weeds such as black
nightshade, common ragweed, and lambsquarters. It
is somewhat less effective on giant ragweed, annual
morningglories, and velvetleaf. Atrazine premix products, such as Degree Xtra, Bicep II Magnum, Keystone,
Guardsman Max, are commonly used broad spectrum
herbicides for popcorn and sweet corn, although not all
premixes are labeled for both types of corn. Application of a three-way premix, such as Lumax or Lexar, will
improve control of the broadleaf weeds that atrazine
premix products fail to adequately control.
73
Table 11. Weed Response to Herbicides in Popcorn and Sweet Corn—Grasses
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for additional information on site of action classification.
Site of action
Barnyardgrass
Crabgrass
Fall panicum
Field sandbur
Giant foxtail
Yellow foxtail
Shattercane
Seedling johnsongrasss
Rhizome johnsongrass
Quackgrass
Woolly cupgrass
Yellow nutsedge
Grasses
15
5/15
14/15
5/15
5
27
5/27/15
15
5/15
15
3
14
14/15
14/27
15
9
9
8
8
8
9
8
9
8
8
8
8
8
9
9
8
8
6
9
9
9
8+
8
8
9
8
8
8
8
8
8
8+
8
8
8
8
8+
8
7
7
6
6
6
6
6
6
6
7
6
6
6
9
9
9
9
7
9
9
9
8+
8
8
9
9
9
9
8
8
7
9
9
9
8+
8
8
9
8
6
-
6
-
-
6
6
8
6
6
-
7+
7+
6
6
7
7
7
7
8
7
7
6
8+
8+
6
7
8
8+
8
8
8
8+
-
4
14
5
6
2
6
14
27
5/27
2/27
4
9
27
5/27
5/6
27
5/27
10
2
2/4
2
14/27
2
4/19
4
2/4
7
8
8
7
8
8
8
6
8
6
-
7*
7*
8
8
7
8
8
8
8
7*
6
-
8
8
8
6
6
8
8
7
7
6
-
6
8
8
6
6
7
8
6
-
8
7
8+
9
7+
8
7
8
8
9
6
6
6
-
8
7
9
9
7
7+
9
9
6
9
6
6
6
-
9
8
9
6
6
8
8
8
9
9
9
-
9
8
9
7
7
8
8
8
9
9
9
-
7
7
9
7
7
7
9
6
6
-
7
8
7
9
7
7
6
9
7
7
-
6
9
6
6
7+
7+
8+
8
-
7
8
6
7
8+
6
9
9
Preplant or Preemergence
Acetochlor
Acetochlor+atrazine
Anthem
Anthem ATZ
Atrazine
Callisto
Lumax / Lexar EZ
Metolachlor
Metolachlor + atrazine
Outlook
Pendimethalin1
Sharpen (popcorn only)
Verdict (popcorn only)
Zemaz
Zidua
Postemergence
2,4-D (popcorn only)
Aim
Atrazine
Basagran/Broadloom
Beacon (popcorn only)
Bromoxynil
Cadet
Callisto
Callisto Xtra
Capreno (popcorn only)
Dicamba (popcorn only)
Glyphosate2
Impact/Armezon
Impact /Armezon + atrazine
Laddok
Laudis
Laudis + atrazine
Liberty2
Nicosulfuron
NorthStar (popcorn only)
Permit/Sandea/Halomax
Solstice
Spirit (popcorn only)
Status (popcorn only)
Stinger
Yukon (popcorn only)
1Popcorn—apply pendimethalin after planting or postemergence; sweet corn—apply pendimethalin postemergence only. Provides residual weed control only, not control of emerged weeds.
2Apply glyphosate only to Roundup Ready sweet corn hybrids, and Liberty only to Attribute Bt11 (glufosinate-resistant) sweet corn hybrids.
*Large crabgrass only.
Popcorn and Sweet Corn
Weed control rating: Crop tolerance rating:
9 = 90% to 100% 0 = Excellent
8 = 80% to 90% 1 = Good
7 = 70% to 80% 2 = Fair
6 = 60% to 70% 3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
74
Table 12. Weed Response to Herbicides in Popcorn and Sweet Corn—Broadleaf Weeds
Weed control rating: Crop tolerance rating:
9 = 90% to 100% 0 = Excellent
8 = 80% to 90% 1 = Good
7 = 70% to 80% 2 = Fair
6 = 60% to 70% 3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
Burcucumber
Cocklebur
Common ragweed
Common ragweed (group 2-R)
Giant ragweed
Giant ragweed (group 2-R)
Jimsonweed
Kochia
Lambsquarter
Lambsquarter (group 5-R)
Palmer amaranth (group 2-R)
Palmer amaranth (group 2+9-R)
Pigweed (redroot/smooth)
Smartweed
Velvetleaf
Waterhemp (group 2-R)
Waterhemp (group 2+9-R)
Waterhemp (group 2+9+14-R)
Preplant or Preemergence
Acetochlor
Acetochlor+atrazine
Anthem
Anthem ATZ
Atrazine
Callisto
Lumax / Lexar EZ
Metolachlor
Metolachlor + atrazine
Outlook
Pendimethalin1
Sharpen (popcorn only)
Verdict (popcorn only)
Zemaz
Zidua
Postemergence
2,4-D (popcorn only)
Aim
Atrazine
Basagran/Broadloom
Beacon (popcorn only)
Bromoxynil
Cadet
Callisto
Callisto Xtra
Capreno (popcorn only)
Dicamba (popcorn only)
Glyphosate2
Impact/Armezon
Impact /Armezon + atrazine
Laddok
Laudis
Laudis + atrazine
Liberty2
Nicosulfuron
NorthStar (popcorn only)
Permit/Sandea/Halomax
Solstice
Spirit (popcorn only)
Status (popcorn only)
Stinger
Yukon (popcorn only)
Black nighshade
Broadleaf Weeds
Annual morningglory
Popcorn and Sweet Corn
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for additional information on site of action classification.
8
7
8
6
8
8
8
8
6
-
8+
9
8
9
9
9
9
8
9
8+
9
9
9
8
6
6
6
7
7
6
?
7
-
8
7
8
8
8
8
8
7
-
7
9
7
9
9
7
9
9
9
9
7
7
7
9
7
9
9
7
9
9
9
9
7
7
8
6
8
6
8
8
8
8
6
-
8
6
8
6
8
8
8
8
6
-
9
7
9
9
9
8
8
-
9
7+
8
9
9
9
9
7
8
8
8
7+
7+
9
8
9
9
9
9
6
9
6
8
9
9
9
8
7+
7+
8
8
9
9
6
6
6
8
9
9
9
8
8
9
8
8+
8
7
9
7
8+
7+
7
8
9
8
8
8
9
8
8+
8
7
9
7
8+
7+
7
8
9
8
8
8+
9
8
9
9
9
9
8
9
8
9
9
9
9
8
9
9
9
9
9
9
9
9
9
-
8
7
8
8
9
9
8
8
8
9
7
8
9
8
8+
8
7
9
7
8+
7+
7
8
9
8
8
8
9
8
8+
8
7
9
7
8+
7+
7
8
9
8
8
8
9
8
8+
8
7
9
7
8+
7+
7
8
9
8
8
9
8
9
6
8
7
7
8
7
9
6
7
8
8
7
8
8
8
8
6
8
7
9
8
7
8
9
8
9
9
9
9
8
8
9
9
8
9
9
9
9
9
8
8
8
7
8
9
7
8
9
8
7
8
7+
8
6
7
8
8
8
9
8
9
7
7
9
9
9
9
9
7+
9
8
9
9
8
9
9
8
9
9
9
9
8
9
9
9
9
9
6
9
7
9
9
7+
9
8
9
8+
7
9
9
8
9
9
9
8
7
9
9
9
9
9
6
9
7
9
7+
9
8
9
8+
7
9
9
8
9
9
7
7
9
9
7
9
8
6
9
8
8
9
8
9
8+
7
9
9
8
9
9
9
8
8
9
9
9
9
9
8
6
8
8
9
8
9
8+
7
9
9
8
9
9
6
8
9
9
7
7
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
8
9
8
9
9
9
8
9
7+
7+
9
7
8
9
6
8
9
8+
8
8
8+
9
9
8
9
8
8
7
8
8
8
8
9
7
9
6
9
7
9
9
9
9
8+
9
9
9
9
9
7
9
9
6
9
8
9
7
6
9
7
9
9
9
9
8+
9
9
5
9
9
7
9
9
6
9
8
8
8+
8
9
8
8
8
8
9
7+
8
9
8
7
9
8
7+
8
8+
8
9
8
8
8
9
7+
8
9
8
7
9
8
7+
9
8
9
9
7
8
8
9
9
9
9
9
9
9
9
9
8
9
9
9
9
9
9
9
6
9
9
8
8
9
9
8
8
8
8
9
9
8
9
9
8
9
7
9
8
8+
9
8
9
8
8+
8
8
9
9
9
9
7
8
9
9
9
9
9
8
8
8
9
8
8
9
8
8+
8
9
8
8
9
8
9
7+
8
9
8
7
9
8
7+
8
8+
8
9
8
8
8
9
7+
8
9
8
7
9
8
7+
8
8+
8
9
8
8
8
9
7+
8
9
8
7
8
8
7+
1Popcorn—apply pendimethalin after planting or postemergence; sweet corn—apply pendimethalin postemergence only. Provides residual weed control only, not control of emerged weeds.
2Apply glyphosate only to Roundup Ready sweet corn hybrids, and Liberty only to Attribute Bt11 (glufosinate-resistant) sweet corn hybrids.
*Large crabgrass only.
75
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
Herbicide
Formulation
Acetochlorvarious
в– в– Acetochlor (plus safener) is sold under various
trade names, including Harness, Breakfree NXT,
Surpass NXT, Degree, Confidence, and Volley.
Check label to make sure the product is labeled
for sweet corn.
в– в– Acetochlor controls annual grasses, pigweed,
and black nightshade, and controls or suppresses
yellow nutsedge, lambsquarters, and common
ragweed. Control of lambsquarters and common
ragweed will generally be less effective compared
to most broadleaf herbicides, but more effective
than other acetamide herbicides.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Degree is an encapsulated product that can
provide a longer period of annual grass control
compared to other acetochlor products.
в– в– Acetochlor products can be applied after planting
but prior to weed emergence, and before corn
height exceeds 11 inches. All acetochlor products
except Degree must be applied using water as the
spray carrier after the corn has emerged.
в– в– Degree and Degree plus atrazine can be applied
to emerged popcorn in water or UAN, but popcorn
should not exceed 6 inches in height if fertilizer
solution is used as the carrier. Do not apply in
fertilizer solution when air temperatures exceed
85 degrees. Mixtures with products other than
atrazine should be applied only in water if corn has
emerged. Leaf burn may occur when acetachlor is
applied to emerged corn.
в– в– Do not apply postemergence to sweet corn.
Product Rate Range
Degree 3.8L Use Rates (pts/A)
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
2.25 to 3.25
3.25 to 4.25
3.25 to 4.25
3% or more OM*
3.25
3.25 to 4.25
4.25 to 5.0
*On soils with 6 to 10% organic matter (OM) use 4.25 to 6.25.
Harness/Confidence 7EC Use Rates (pts/A)a
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
1.25 to 1.75
1.75 to 2.25
1.75 to 2.25
3% or more OMb
1.75
1.75 to 2.25
2.25 to 2.75
aUse higher rate in recommended rage in areas of high weed infestations.
bOn soils with 6 to 10% OM use 2.5 to 3.4 pt/A.
Breakfree NXT/Surpass/Volley 6.4EC Use Rates
(pt/A) in Conventional Tillage Systems When Applied within 14 Days Before Plantinga
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
1.5 to 2.25
1.5 to 2.5
1.5 to 2.75
3% or more OMb
1.5 to 2.5
1.5 to 2.5
2 to 3
aUse higher rate in recommended range in areas of high weed infestations.
Surpass/Volley 6.4EC Use Rates (pt/A) in Reduced
or No-Till systems or Conventional Systems When
Applied More Than 14 Days Before Planting
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
2
2 to 2.5
3
3% or more OMb
2
2.5
3
Popcorn and Sweet Corn
AAtrex/atrazine 4L
2 - 4 pt
90DF
1.1 - 2.2 lb
в– в– Site of action: group 5 (see pages 14-15).
в– в– Atrazine is generally applied at a rate of 1.4 to 2 pounds active ingredient per acre to control broadleaf weeds.
в– в– Rates approaching 2 pounds active ingredient will improve control of velvetleaf, cocklebur, giant ragweed, and
morningglory. Atrazine will not control fall panicum, regardless of rate.
в– в– Maximum soil-applied rate on soils not highly erodible is 2 pounds of active ingredient per acre. Maximum rate on
highly erodible soils is 2 pounds active ingredient on fields with at least 30% crop residue, and 1.6 pounds active
ingredient on fields with less than 30% crop residue. Soil applications may be followed with a postemergence application of atrazine, but total of all treatments cannot exceed 2.5 pounds active ingredient per acre per year.
в– в– Plant only corn or sorghum the year of atrazine application.
в– в– Where oats, forage legumes, or forage grasses will be planted the following spring, do not apply more than 0.8
pounds active ingredient per acre.
76
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Popcorn and Sweet Corn
Herbicide
Formulation
Acetochlor + atrazine
Various
в– в– Acetochlor plus atrazine (plus safener) is sold
under various trade names, including Harness
Xtra, Degree Xtra, Fultime, Keystone, Breakfree
ATZ, Confidence Xtra, and Volley ATZ. These
premix products control annual broadleaves
and grasses in popcorn. The ratio of atrazine to
acetochlor varies with product, and some products require the addition of atrazine or another
broadleaf herbicide for the effective control of
some broadleaf weeds. Check label to make
sure the product is labeled for sweet corn.
в– в– Degree Xtra and Fultime are encapsulated
formulations that can provide a longer period of
annual grass control compared to other acetochlor products.
в– в– Site of action: group 5 (atrazine), group 15 (acetochlor). See pages 14-15.
в– в– Can be applied after planting and before corn
height exceeds 11 inches and before weeds
reach the 2 leaf-stage. When mixing with postemergence herbicides to control larger weeds,
follow the most restrictive label with regard to
maximum popcorn size.
в– в– All acetochlor products except Degree Xtra
should be applied using water as the spray carrier after the popcorn has emerged.
в– в– Degree Xtra can be applied in water or UAN,
but popcorn should not exceed 6 inches in
height if fertilizer solution is the carrier. Do not
apply in fertilizer solution when temperature exceeds 85 degrees. Mixtures with products other
than atrazine should be applied only in water
if the corn has emerged. Leaf burn may occur
when applied to emerged corn.
в– в– Do not apply postemergence to sweet corn.
Product Rate Range
Degree Xtra 4L Use Rates (qt/A)
Soil Texture
Coarse
Medium*
Fine*
2.9
2.9 to 3.7
3.2 to 3.7
*In areas of heavy weed pressure rates can be increased to 4.3 qts/A.
FulTime 4L Use Rates (qt/A) in Conventional Tillage
Systems When Applied Within 14 Days Before Planting
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
2.5 to 2.7
2.7 to 3.3
3 to 3.5
3% OM or more
2.7 to 3
3 to 3.3
3 to 5
FulTime 4L Use Rates (qt/A) in Reduced or No-Till
Systems or Conventional Systems When Applied
More Than 14 Days Before Planting
Time From Application
Soil
Greater than 10 days Less than 10 After plantTexture
before planting
days before or ing and/or
after planting emergence
Coarse
Do not apply more than
2.5 to 3
2.5 to 3
14 days before planting
Medium
2.7 to 4
2.7 to 3.3
2.7 to 3.3
Fine
3.3 to 5
3 to 5
3 to 4
Harness Xtra/Confidence Xtra 5.6L Broadcast Rate
(qt/A)*
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
1.4
1.7 to 2.4
2.3 to 2.6
3% or more OM
1.7
2.3 to 2.6
2.3 to 3.0
* In areas of heavy infestations use up to 2.3 qt/A on coarse-textured soils and 2.3 to 3.0
qt/A on medium- and fine-textured soils, but do not exceed 2.5 qt/A on highly erodible soils
with less than 30% plant residue.
Breakfree ATZ/Keystone/Volley ATZ 5.25: Use Rate in
Conventional Tillage (qt/A)
Soil Texture
Coarse
Medium
Fine
Less than 3% OM
2.2 to 2.4
2.4 to 2.8
2.6 to 3.0
3% or more OM
2.4 to 2.6
2.6 to 2.8
2.6 to 3.4
Herbicide
Formulation
Product Rate Range
Callisto 4L 6 - 7.7 fl oz
в– в– Yellow popcorn and sweet corn only. Do not apply to white popcorn.
в– в– Callisto (mesotrione) can be applied preplant or preemergence for control of annual broadleaf weeds. Callisto can
help control giant ragweed, cocklebur, and morningglory in mixtures with atrazine.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Callisto does not control grass weeds, and should be applied in combination with Harness, Dual II Magnum, TopNotch, or another acetamide grass herbicide, or an acetamide/atrazine premix (Bicep II Magnum, Degree Xtra, etc.).
77
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Anthem Broadcast Rates (oz/A)a
Soil Texture
Group
Coarse
Medium
Fine
Less than 3% OM
7 to 8
8 to 10
9 to 11
3% or Greater
OM
7 to 8
8 to 11
10 to 13
a. Rates may increase when applied more than 14 days prior to planting, and
decrease when used postemergence - see label.
Anthem ATZ Broadcast Rates (pt/A)a
Soil Texture
Group
Coarse
Medium
Fine
Less than 3%
OM
1.75 to 2
2 to 2.5
2.25 to 3
3% or Greater
OM
1.75 to 2
2 to 2.75
2.5 to 4
a. Rates may increase when applied more than 14 days prior to planting, and
decrease when used postemergence - see label.
Herbicide
Formulation
Lumax EZ
3.67L
2.7 - 3.25 qts
Lexar EZ
3.7L
3 - 3.5 qts
в– в– Yellow popcorn and sweet corn only. Do not apply to white popcorn.
в– в– Lumax and Lexar are premixes of atrazine plus s-metolachlor (Dual II Magnum) plus mesotrione (Callisto) for control
of grass and broadleaf weeds in corn. See descriptions for these products for more information.
в– в– Site of action: group 5 (atrazine); group 15 (s-metolachlor); group 27 (mesotrione).
в– в– Control most annual broadleaf weeds, but expect partial control of giant ragweed, cocklebur, and annual morningglory.
в– в– Can be applied preplant or preemergence. Do not apply postemergence to popcorn or sweet corn. Emerged
broadleaf weeds should be less than 3 inches tall at the time of application. Control of emerged grasses (up to 1.5
inches tall) will require additional atrazine.
Herbicide
Formulation
s-metolachlor7.64E
metolachlor7.8E
в– в– S-metolachlor (Dual II Magnum, Cinch) and metolachlor (Stalwart C, Parallel)
control annual grasses and pigweed, and control or suppress waterhemp,
black nighshade, and yellow nutsedge.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Can be applied preplant or preemergence before corn and weeds emerge.
Can be applied postemergence with atrazine up to 5-inch corn or as a
directed spray up to 12-inch corn, and before grass and broadleaf weeds
exceed the 2-leaf stage. Do not apply using fertilizer solution as the spray
carrier after the corn has emerged.
в– в– May be applied up to 30 days before planting as a single application.
в– в– Incorporation to a depth of 2 inches will improve yellow nutsedge cotnrol
and reduce dependence on rainfall.
в– в– Allow 30 days between application and harvest of sweet corn.
Product Rate Range
Use rates for Dual II Magnum,
Cinch, Parallel, and Stalwart
(pt/A)
Soil
Texture
Less than
3% OM
3% or
more OM
Coarse
1.0 to 1.33
1.33
Medium
1.33 to 1.67
1.33 to 1.67
Fine
1.33 to 1.67
1.67 to 2.0
Popcorn and Sweet Corn
Herbicide
Formulation
Anthem2.15L
Anthem ATZ
4.5L
в– в– Anthem (pyroxasulfone + fluthiacet-methyl) and Anthem ATZ (atrazine + pyroxasulfone + fluthiacet) can be applied preplant, preemergence, or early postemergence in field corn, seed corn, popcorn, and sweet corn for residual control of
annual grasses and broadleaf weeds. These products should be combined with other preemergence corn herbicide(s)
to improve the longevity and spectrum of weed control, or followed with a postemergence herbicide treatment.
в– в– Site of action: Anthem - group 14/15; Anthem ATZ - group 5/14/15 (see pages 14-15).
в– в– Corn seed must be planted a minimum of one inch deep.
в– в– Anthem will not generally provide adequate control of emerged weeds when applied early postemergence. The
addition of atrazine in Anthem ATZ improves activity on emerged weeds but will generally still require the addition
of glyphosate or other postemergence herbicide.
78
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Popcorn and Sweet Corn
Herbicide
Formulation
S-metolachlor + atrazine
5.5L
metolachlor + atrazine
5.5L
в– в– S-metolachlor plus atrazine (Bicep II Magnum, Brawl II
ATZ, Cinch ATZ) and metolachlor plus atrazine (Stalwart
Xtra, Parallel Plus, Trizmet) control annual grass and
broadleaf weeds in corn.
в– в– Site of action: group 5 (atrazine), group 15 (S-metolachlor/
metolachlor). See pages 14-15.
в– в– Can be applied preplant, preemergence, and after corn
emergence until corn plants are 5 inches tall and before
weeds exceed the 2-leaf stage. Do not apply using fertilizer solution as the spray carrier after crop emergence.
в– в– Allow 30 days between application and harvest of sweet
corn.
Herbicide
Product Rate Range
Bicep II Magnum/Cinch ATZ Use Rates (qt/A)
Soil Texture
Less than 3%
OM
3% or more OM
Coarse
1.3
1.6
Medium
1.6
2.1
Fine
2.1
2.1a
2.1 to 2.6b
Muck or Peat
Do not use
Do not use
a Do not exceed this rate on highly erodible land with less than 30% plant
residue cover.
b For cocklebur, yellow nutsedge, and velvetleaf control on fine-textured soils
above 3% OM, apply 3.0 qt/A Bicep II.
Stalwart Xtra Use Rates (qt/A)
Soil Texture
Less than 3%
OM
3% or more OM
Coarse
1.3
1.6
Medium
1.6
2.1
Fine
2.1
2.1
Formulation
Outlook6EC
в– в– Outlook (dimethenamid-P) controls annual grasses and
pigweed, and controls or suppresses yellow nutsedge
and black nightshade.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Can be applied preplant, preemergence, but must be
applied before weed emergence, or in a mixture with
herbicides that control emerged weeds. Do not apply to
corn that is more than 12 inches tall.
в– в– Can be applied after corn has emerged with surfactant or
low rates of liquid fertilizer. Do not use fertilizer solution
as the spray carrier after crop has emerged. COC should
not be added after the crop has emerged unless specified for a particular tank mixture.
в– в– Consult your seed company regarding hybrid tolerance
to Outlook. Do not harvest sweet corn for 50 days after
application. Do not make any layby applications to sweet
corn.
Product Rate Range
Outlook Use Rates (fl oz/A)
Soil Texture
Less than 3%
OM
3% or more OM
Coarse
10 to 14
14 to 18
Medium
14 to 16
16 to 20
Fine
16 to 18
18 to 21
79
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Herbicide
Formulation
Prowl/Pendimax Use Rates (pt/A)
Soil Organic Matter Content
Soil Texture
Less than
1.5%
1.5 to 3%
More than
3%
Coarse
1.8 to 2.4
2.4 to 3.6
3.6
Medium
2.4 to 3.6
3.6
3.6 to 4.8
Fine
2.4 to 3.6
3.6 to 4.8
3.6 to 4.8
Prowl H2O/Satellite Hydrocap Use Rates (pt/A)
Soil Organic Matter Content
Soil Texture
Less than
1.5%
1.5 to 3%
More than
3%
Coarse
2
3
3
Medium
3
3
4
Fine
3
4
4
Herbicide
Formulation
Sharpen2.85SC
в– в– Sharpen (saflufenacil) controls or suppresses annual broadleaf weeds in popcorn. Check with seed supplier for
information on varietal tolerance to Sharpen before using. Do not use on sweet corn.
в– в– The addition of atrazine will improve control of large-seeded broadleaf weeds such as giant ragweed, morningglory,
and cocklebur. Sharpen can also be added to other preemergence corn products to improve residual control of
broadleaf weeds. Do not apply Sharpen after corn has emerged.
в– в– Site of action: group 14. See pages 14-15.
в– в– This product is intended for use in a planned preemergence followed by postemergence program, and the product rates are not intended to provide full-season weed control. Preemergence or preplant application of Sharpen
should be followed by application of postemergence herbicides as needed.
в– в– Sharpen rates are based on soil texture as follows: coarse - 2 to 2.5 oz; medium - 2.5 to 3 oz; fine - 3 to 3.5 oz.
в– в– Do not apply Sharpen where an at-planting application of an organophosphate or carbamate insecticide us planned
or has occurred or severe injury can occur. See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– Preplant application of Sharpen and atrazine can control small, emerged weeds in no-till, including marestail.
Glyphosate should be added when weeds are more than about 4 inches tall and for weeds Sharpen does not control (see label). For control of emerged weeds, apply with MSO (1% v/v) and AMS (8.5 to 17 lbs/100 gallons) or UAN
(1.25 to 2.5% v/v). Use a spray volume of 15 to 20 gpa in no-till burndown situations, or where emerged weeds are
present. Flat fan nozzles are recommended for burndown applications.
Popcorn and Sweet Corn
Pendimethalin/Pendimax/
Pendant/etc3.3EC
Prowl H2O/Satellite Hydrocap
3.8CS
в– в– Apply in conventional systems only, do not apply in
minimum or no-till systems. Apply only after planting.
Do not incorporate or severe injury may result.
в– в– The active ingredient in these products, pendimethalin
controls annual grasses, pigweed, and lambsquarters
(including triazine-resistant biotypes), and helps control smartweed, velvetleaf, and seedling johnsongrass.
Pendimethalin is often combined with atrazine for
control of grass and broadleaf weeds where triazineresistant pigweed and lambsquarters are a problem.
в– в– Site of action: group 3 (see pages 14-15).
в– в– Do not apply preplant or preemergence on sweet corn.
в– в– Can be applied postemergence until popcorn and
sweet corn are 20 to 24 inches tall. Where the corn
canopy prevents spray particles from reaching the soil,
use drop nozzles and apply as a directed spray. Postemergence applications provide residual control only,
not control of emerged weeds.
в– в– To reduce the risk of corn injury, plant at least 1.5 inches
deep and ensure seed to soil contact. Combining pendimethalin with dicamba may increase the potential for
crop injury, especially when corn is under stress from
cool, wet conditions.
Product Rate Range
80
Popcorn and Sweet Corn
Popcorn and Sweet Corn: Soil-Applied Herbicides—Preplant or Preemergence
Herbicide
Formulation
Verdict5.57EC
в– в– Verdict is a premix of dimethenamid-P (Outlook) and saflufenacil (Sharpen) that controls annual grass and broadleaf
weeds in popcorn. Check with seed supplier for information on varietal tolerance to Verdict before use.
в– в– The addition of atrazine will improve control of large-seeded broadleaf weeds such as giant ragweed, morningglory,
and cocklebur.
в– в– Site of action: Group 15 (dimethenamid-P); group 14 (Saflufenacil). See pages 14-15.
в– в– This product is intended for use in a planned preemergence followed by postemergence program, and the product
rates are not intended to provide full-season weed control. Preemergence or preplant application of Verdict should
be followed by application of postemergence herbicides as needed.
в– в– Verdict rates are based on soil texture as follows: coarse - 10 to 12 oz; medium - 13 to 15 oz; fine - 16 to 18 oz.
в– в– Do not apply Verdict where an at-planting application of an organophosphate or carbamate insecticide us planned
or has occurred or severe injury can occur. See product label and Table 10 for more information on herbicide-insecticide interactions.
в– в– Preplant application of verdict can control small, emerged weeds in no-till, especially when combined with atrazine. Glyphosate should be added when weeds are more than about 4 inches tall, and for weeds Verdict does not
control (see label). For control of emerged weeds, apply with MSO (1% v/v) and AMS (8.5 to 17 lbs/100 gallons) or
UAN (1.25 to 2.5% v/v). Do not apply Verdict after corn has emerged. Use a spray volume of 15 to 20 gpa in no-till
burndown situations, or where emerged weeds are present. Flat fan nozzles are recommended for burndown applications.
Herbicide
Formulation
Product Rate Range
Zemax
3.76ZC
2 to 2.4 qt
в– в– Zemax is a premix of mesotrione (Callisto) and s-metolachor (Dual II Magnum) that controls annual grass and broadleaf weeds in corn. The addition of atrazine will improve control of large-seeded broadleaf weeds. See Callisto and
s-metolachlor descriptions for more information.
в– в– Site of action: group 14 (s-metolachlor); 27 (mesotrione). See pages 14-15.
в– в– Can be applied preemergence to most types of corn, including popcorn (yellow only), sweet corn, and corn grown
for seed. Do not apply postemergence to popcorn or sweet corn.
в– в– Application rates: 2 qts/A - less than 3% soil OM; 2.4 qts/A - 3% or greater soil OM.
Herbicide
Formulation
Zidua85WDG
в– в– Zidua (pyroxasulfone) can be applied preplant, preemergence, or early postemergence in field corn, seed corn,
popcorn, and sweet corn for residual control of annual grasses and small-seeded broadleaf weeds. This product
should generally be combined with other preemergence corn herbicide(s) to improve broadleaf weed control, or
followed with a postemergence herbciide treatment.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Application rates based on soil texture: coarse - 1.5 to 2.75 oz; medium - 2 to 3 oz; fine - 2.5 to 4 oz. The label allows rates lower than those listed here when applied postemergence or used in a planned sequential (PRE + POST)
program.
в– в– Corn seed must be planted a minimum of one inch deep.
в– в– Early postemergence applications will not control emerged weeds.
81
Popcorn and Sweet Corn: Postemergence Herbicides—Contact
Herbicide
Formulation
Product Rate Range
AAtrex / atrazine
4L
1.5 - 2 qt
90DF
1.67 - 2.22 lb
в– в– Site of action: group 5 (see pages 14-15).
в– в– Maximum rate for postemergence application to fields without soil-applied atrazine in the same year is 2 pounds active ingreadient/A. When applied postemergence to fields with soil-applied atrazine the same year, total amount of
atrazine applied may not exceed 2.5 pounds of active ingredient.
в– в– For annual grass control, apply 2 lba ai/A when grasses are no more than 1.5 inches tall. Atrazine will not control fall
panicum.
в– в– For control of broadleaf weeds, rates of 1.2 pounds of active ingredient may be sufficient. Apply until broadleaf
weeds are 4 inches tall.
в– в– Apply with COC (1% v/v) for best results. Mix atrazine with water first, and add oil last.
в– в– Apply when popcorn or sweet corn is less then 12 inches tall.
Herbicide
Formulation
Product Rate Range
Basagran/Broadloom
4L
1.5 to 2 pt
в– в– Basagran/Broadloom (bentazon) is a contact herbicide that controls many annual broadleaf weeds, including cocklebur, velvetleaf, and Pennsylvania smartweed. Controls or suppresses Canada thistle and yellow nutsedge.
в– в– Site of action: group 6 (see pages 14-15).
в– в– For best results, apply with COC when weeds are in the 2- to 6-leaf stage.
в– в– Apply in combination with atrazine for control of pigweed, lambsquarters, and ragweed.
в– в– Consult your seed company regarding sweet corn hybrid tolerance to Basagran.
Popcorn and Sweet Corn
Herbicide
Formulation
Product Rate Range
Aim 2EC
0.5 -1 oz
в– в– Aim (carfentrazone-ethyl) is a contact herbicide that controls black nightshade, velvetleaf, redroot pigweed, and
small annual morningglories and lambsquarters. Aim is often mixed with other broadleaf herbicides to improve
control of velvetleaf.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply when weeds are 1 to 4 inches tall for best results. Velvetleaf can be controlled up to 36 inches tall. Apply
before corn exceeds the 8-collar stage.
в– в– Apply with NIS (0.25% v/v). UAN (2 to 4 gallons/100 gallons) or AMS (2 to 4 lbs/A) can be added if recommended
for use with other herbicides in a mix with aim. In general, Aim should not be mixed with COC or EC formulations of
other herbicides in order to avoid excessive crop injury. The label does allow use of COC under dry conditions and
in specific mixtures. Add Aim to the spray tank first, before adding other products.
в– в– Apply in a spray volume of 10 to 20 gpa with a pressure of 20 to 40 psi. Flat fan nozzles are recommended for
adequate spray coverage.
в– в– Aim usually causes leaf speckling and necrosis. The severity of injury varies with environmental conditions, adjuvants, tank-mix partner. To reduce injury, 1) do not apply within 6 to 8 hours of rain, 2) make sure spray nozzles are
positioned at least 18 inches above the crop, and 3) avoid direction of excessive amounts of herbicide into the corn
whorls.
в– в– Not all sweet corn hybrids have been tested for their tolerance to Aim. The user assumes all liability for crop injury
when Aim is applied to sweet corn.
82
Popcorn and Sweet Corn
Popcorn and Sweet Corn: Postemergence Herbicides—Contact
Herbicide
Formulation
Product Rate Range
Bromoxynil
2S
1 - 1.5 pt
в– в– Do not apply to popcorn prior to the 3-leaf stage. Not labeled for sweet corn.
в– в– Bromoxynil is sold under various trade names, including Buctril, Moxy, and Broclean. Bromoxynil is a contact herbicide that controls annual broadleaf weeds, including black nightshade, cocklebur, ragweeds, lambsquarters, and
smartweeds, but is weak on pigweed and large velvetleaf.
в– в– Site of action: group 6 (see pages 14-15).
в– в– Do not apply until the 3-leaf popcorn stage. Can be applied until tassel emergence. The 1.5-pint rate may be applied after corn reaches the 4-leaf stage and before tassel emergence. Maximum corn size at the time varies with
tank-mix partner.
в– в– Do not use surfactant or crop oil when applying bromxynil alone or with most other herbicides. NIS and fertilizer
solution are allowed in some tank mixtures.
в– в– Apply in a minimum volume of 10 gpa at a minimum pressure of 30 psi using flat fan nozzles. May cause leaf burn,
but effect are usually temporary.
Herbicide
Formulation
Product Rate Range
Cadet
0.91EC
0.4 - 0.9 oz
в– в– Cadet (fluthiacet-methyl) is a contact herbicide that controls velvetleaf, and controls or suppresses small lambsquarters, pigweeds, black nightshade, and annual morningglory at the 0.9 oz rate.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Can be applied to field corn, popcorn, seed corn, and sweet corn (processing only) from the 2-collar stage up to 48
inches tall. Apply before tassel emergence. Not labeled for freash market sweet corn.
в– в– Apply with NIS (0.25% v/v), or a COC or MSO (1 to 2 pts/A). UAN (1 to 2 qts/A) or AMS can be added. When combined with other herbicides, Cadet can generally be applied with any adjuvants required for those herbicides.
в– в– Apply in a minimum spray volume of 15 gpa and pressure of 20-40 psi. Increase volume and pressure in dense
crop and weed canopies.
в– в– Allow 40 days between application and harvest of sweet corn.
Herbicide
Formulation
Product Rate Range
Laddok S-12
5L
1.3 - 2.3 pt
в– в– Do not apply to popcorn seed production fields.
в– в– Laddok/Headline is a 1:1 premix of bentazon (Basagran) plus atrazine for control of most broadleaf weeds, and suppression or control of yellow nutsedge, Canada thistle, and some perennial vines.
в– в– Site of action: group 5 (atrazine); group 6 (bentazon). See pages 14-15.
в– в– Application rate with species and size. Apply with UAN solution, AMS, nonphytotoxic oil concentrate, or Dash. The
label allows combinations of spray additives, which vary with the weed species present. UAN or AMS should be
added when velvetleaf is the target weed, and may also increase control of cocklebur and Pennsylvania smartweed.
COC should also be added when common lambsquarters, common ragweed, Canada thistle, yellow nutsedge, or
field bindweed is present.
в– в– Apply in a spray volume of at least 10 gpa with a minimum pressure of 40 psi. Increasing the spray volume (up to 50
gpa) will improve control when the crop and weed foliage is dense.
в– в– To suppress Canada thistle, apply 2.3 pints when thistle plants are 8 to 10 inches tall until the bud stage.
в– в– A single application of 2.3 pints of Laddok can suppress yellow nutsedge that is 1 to 4 inches tall.
в– в– Provides more effective control of velvetleaf, annual morningglory, lambsquarters, and pigweed than Basagran
alone, but is no more effective on triazine-resistant lambsquarters.
83
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
Herbicide
Formulation
Product Rate Range
Callisto
4L
3 fl oz
в– в– Apply only to yellow popcorn or sweet corn up to 30 inches tall or the 8-leaf stage. Apply when weeds are less
than 5 inches tall for best results.
в– в– Callisto (mesotrione) is a systemic herbicide that controls annual broadleaf weeds, including cocklebur, atriplex,
lambsquarters (including triazine-resistant), giant ragweed, Pennsylvania smartweed, pigweeds, waterhemp, velvetleaf, and black nightshade. Callisto alone does not provide consistent control of common ragweed or morningglory, and can be variable on giant ragweed.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Apply with COC (1% v/v). Do not use MSO (MSO), MSO blend adjuvants, AMS, or UAN.
в– в– To avoid crop injury, do not apply Callisto postemergence in a tank-mix with emulsifiable concentrate grass herbicides (Dual II Magnum, etc). See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar insecticides.
в– в– Herbicide sensitivity in sweet corn and yellow popcorn varies widely, and not all sweet corn and yellow popcorn
hybrids have been tested. Contact your sweet corn or popcorn company or agronomist about hybrid recommendations before making a postemergence application of Callisto to sweet corn or yellow popcorn.
Herbicide
Formulation
Product Rate Range
Callisto Xtra
3.7L
20 to 24 oz
в– в– Callisto Xtra is a premix of mesotrione (Callisto) and atrazine that controls annual broadleaf weeds. See Callisto
description for more information.
в– в– Site of action: group 27 (mesotrione); group 5 (atrazine). See pages 14-15.
в– в– Apply when weeds are less than 5 inches tall for best results. Can be applied to sweet corn and yellow popcorn
from emergence up to 12 inches tall.
в– в– Apply with COC (1% v/v) or NIS (0.25% v/v). COC is the preferred adjuvant to maximize activity, but increases the
risk of crop injury. Applying when weeds are less than 5 inches tall will minimize the need for COC. Do not use
MSO (MSO) or MSO blend adjuvants, UAN or AMS.
в– в– Apply in a spray volume of 10 to 30 gpa, but use a volume of at least 15 gpa if weed foliage is dense.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides. Do not apply Callisto Xtra postemergence in a mixture with emulsifiable concentrate grass herbicides.
Popcorn and Sweet Corn
Herbicide
Formulation
Product Rate Range
Beacon
75DF
3/8 -3/4 oz
в– в– Risk of severe injury - check with popcorn seed supplier or chemical representative for sensitivity of inbreds/hybrids. Not labeled for sweet corn.
в– в– Can be applied only as a directed spray using drop nozzles, when popcorn is between 10 and 48 inches tall.
Nozzles should be positioned to avoid placing herbicide in whorl. Must be applied before tassel.
в– в– Beacon (primsulfuron) is a translocated sulfonylurea that controls or suppresses annual and perennial grasses and
controls annual broadleaf weeds. Beacon provides partial control of foxtail species and may be less effective than
Accent for rhizome johnsongrass and quackgrass control, but is generally more effective than Accent on broadleaf
weed control. Does not control ALS resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply NIS (0.25% v/v) or COC (1 to 4 pints per acre); COC is generally the preferred additive. COC plus UAN or AMS
can be used when tank-mixing with atrazine, Accent, or dicamba. Most other tank-mixures should be applied with
NIS. See specific label for details.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
84
Popcorn and Sweet Corn
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
Herbicide
Formulation
Product Rate Range
Capreno
3.45SC
3 oz
в– в– Capreno is a premix of tembotrione (Laudis) and thiencarbazone-methyl that can be applied to popcorn for control
of annual grass and broadleaf weeds. This product will provide residual control of grasses also. The addition of
atrazine (0.5 lb/A) will generally improve the speed and effectiveness of control.
в– в– Site of action: group 27 (tembotrione), group 2 (thiencarbazone). See pages 14-15.
в– в– Apply with COC (1% v/v, minimum of 1.25 pt/A) and 28% UAN (1.5 qts/A) or AMS (8.5 lbs/100 gallons, minimum of 1.5
lbs/A). High surfactant oil blends at their recommended rates can replace COC, but do not use NIS or MSO.
в– в– Can be applied broadcast from the V1 to V6 stage of corn, and as a directed spray up to V7. Capreno is most effective when broadleaf weeds are less than 6 inches tall, and grasses are less than 3 inches tall and not tillering.
в– в– Consult seed company for information on varietal tolerance before using Capreno on popcorn.
в– в– Capreno should not be applied to corn that was treated with a soil-applied organophosphate insecticide. See product label and Table 10 for additional information on herbicide-insecticide interactions.
Herbicide
Formulation
Product Rate Range
Dicamba
4L
1/2 - 1 pt
в– в– Risk of injury - check with popcorn seed supplier or chemical representative for sensitivity of selected inbreds/hybrids. Not labeled for sweet corn.
в– в– Dicamba is sold under several trade names such as Banvel, Clarity, Sterling Blue, and Oracle. Dicamba is a translocated herbicide that controls many annual broadleaf weeds, including pigweed, black nightshade, cocklebur, and
Pennsylvania smartweed. Control of velvetleaf can be variable. Dicamba will control or suppress perennial weeds,
especially when mixed with an ALS herbicide.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply 1/2 to 1 pint when corn is in the spike to 5-leaf stage, or until corn is 8 inches tall, whichever occurs first. Do
not apply more than 1/2 to 1 pint on coarse-textured soils. If the 6th true leaf is emerging from the whorl, or corn
is more than 8 inches tall, a rate of 1/2 pint can be applied until corn is 36 inches tall, or until 15 days before tassel
emergence. Apply as a directed spray when corn leaves prevent proper spray coverage, or sensitive crops are
growing nearby.
в– в– The 1 pint rate provides limited residual broadleaf weed control.
в– в– Apply with 1/2 to 1 gallon per acre of UAN (28%) when velvetleaf is a target weed. Can be applied with surfactant
or crop oil to improve control in dry growing conditions. Do not apply with crop oil when corn exceeds 5 inches in
height.
в– в– With any dicamba product, risk of corn injury increases when corn exceeds 8 to 10 inches in height. To reduce risk
of injury, make sure nozzle spacing and boom height are set to minimize interception of spray by the corn plants.
в– в– Soybean and vegetables are extremely susceptible to dicamba drift and vapors. Apply in a spray volume of 20
gpa at a pressure of less than 20 psi to reduce drift. Do not apply where sensitive crops are present if winds over
5 MPH are moving in the direction of the sensitive crops, corn is more than 24 inches tall, soybeans are more than
10 inches tall, or soybeans have begun to bloom. Most dicamba products should not be applied when air temperatures on the day of application will exceed 85 degrees.
Herbicide
Formulation
Product Rate Range
Dicamba + atrazine
3.2L
3.5 pt
в– в– Risk of injury - check with popcorn seed supplier or chemical representative for sensitivity of selected inbreds/hybrids. Not labeled for sweet corn.
в– в– Dicamba + atrazine is sold under several trade names, including Marksman, Sterling Plus, Banvel-K + atrazine, and
Stratos. These products control most annual broadleaf weeds, and suppress or control perennial broadleaf weeds.
в– в– Site of action: group 4 (dicamba), group 5 (atrazine). See pages 14-15.
в– в– Apply when corn is in the spike to five-leaf stage, or until corn is 8 inches tall, whichever comes first. The rate is
85
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
Herbicide
Formulation
Product Rate Range
Impact/Armezon
2.8L
0.75 oz
в– в– Impact/Armezon (topramezone) controls annual broadleaf weeds, including biotypes resistant to ALS inhibitors,
glyphosate, and triazines. Impact controls or suppress small annual grasses. Impact/Armezon is most effective
when applied in combination with 0.25 to 1.5 lbs active ingredient /A of atrazine. The higher atrazine rates will provide residual weed control and more effective control of grasses.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Popcorn inbreds and sweet corn hybrids vary in their tolerance to Impact. Users should check with seed supplier
for information on tolerance prior to use in seed production fields.
в– в– Apply when most broadleaf weeds are emerged and less than 6 inches tall.
в– в– Impact can be applied postemergence up to 45 days before crop harvest. Apply with drop nozzles if the crop canopy prevents adequate spray coverage on weeds.
в– в– For best results, apply with a MSO (1 to 1.5% v/v) plus either UAN (1.25 to 2.5% v/v) or AMS (8.5 to 17 lbs/100 gallons
of water). NIS can be used instead of methylated seed soil if required in tank-mixes with other herbicides.
в– в– Apply in a minimum spray volume of 10 gpa, and apply in 15 gpa when treating large weeds or high-density weed
infestations.
в– в– Impact/Armezon should not be relied upon to provide complete control of grasses, but can control small grasses
(less than 2 inches) that escape preemergence herbicides.
Herbicide
Formulation
Product Rate Range
Laudis
3.5L
3 oz
в– в– Laudis (tembotrione) controls many broadleaf weeds, including biotypes resistant to ALS inhibitors, glyphosate, and
triazines. Impact controls or suppress small annual grasses. Laudis is most effective when applied in combination
with 0.5 lbs active ingredient /A of atrazine.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Check with seed supplier for information on hybrid tolerance prior to use on sweet corn or popcorn.
в– в– Apply when broadleaf weeds are less than 6 inches tall. For most grass species, grasses should be less than 3
inches tall at time of application.
в– в– Apply broadcast up to the V8 stage of popcorn and the V7 stage for sweet corn. Maximum of two applications on
popcorn and one on sweet corn.
в– в– Apply with a MSO (1% v/v, minimum of 1.25 pt/A) plus either UAN (1.5 qt/A) or AMS (1.5 lb/A).
в– в– Apply in a minimum spray volume of 10 gpa, and apply in 15 to 20 gpa in dense weed populations or under adverse
environmental conditions. Use nozzles and pressure that result in medium spray droplets, and increase application
volume when using nozzles that produce coarse spray droplets. Flat fan nozzles of 80 or 110 degrees will provide
optimum postemergence spray coverage.
в– в– Laudis should not be relied upon to provide complete control of grasses, but can control small (less than 2 inches)
grasses that escape preemergence herbicides.
Popcorn and Sweet Corn
3.5 on medium- or fine textured soils with at least 2.5 percent organic matter, and 2 pints on coarse-textured soils.
Provides some residual broadleaf weed control.
в– в– The addition of crop oil, surfactant, or liquid nitrogen fertilizer may improve control, especially when weeds are
drought-stressed. Apply with UAN if velvetleaf is a target weed. Application with crop oils may cause crop injury.
Do not apply with crop oil after corn exceeds 5 inches in height.
в– в– Precautions on spray drift, volatility, and corn injury are the same as for dicamba. See dicamba description above
for more information.
86
Popcorn and Sweet Corn
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
Herbicide
Formulation
Product Rate Range
Nicosulfuron (active ingredient)
Accent Q
54.5DF
0.9 oz
NIC-IT
2L
2 oz
в– в– Accent Q and NIC-IT are labeled for use on popcorn and some sweet corn hybrids grown for processing and fresh
market. Growers should contact seed suppliers for recommendations and information on crop tolerance, and use
of soil-applied organophosphate insecticides, prior to application. Do not apply to any white popcorn inbred or
hybrid unless approved by the seed supplier. Accent and NIC-IT can be used on High Lysine, Waxy, White or other
Food Grade hybrids. A list of approved processing sweet corn hybrids is available from DuPont. With regard to
use of Accent on fresh market sweet corn, the user assumes all risk based on recommendations from university or
seed company personnel, or other experts.
в– в– Can be applied broadcast to popcorn that is less than 20 inches tall or has up to 5 collars (whichever occurs first).
Do not apply broadcast to sweet corn more than 12 inches tall. Drop nozzles can be used up to 18 inches or V6
corn stage.
в– в– Nicosulfuron is a translocated sulfonylurea herbicide that controls annual and perennial grasses and some annual
broadleaf weeds, including Pennsylvania smartweed, pigweed, and annual morningglory. Does not control crabgrass.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Accent Q contains nicosulfuron plus isoxadifen, a safener to reduce the risk of corn injury.
в– в– Apply in a spray volume of at least 15 gpa with a spray pressure of 20 to 40 psi. Increase spray volume and pressure as weed density and size increase. Flat fan or Turbo Floodjet nozzles are recommended.
в– в– To avoid a reduction in grass control or crop injury, do not mix with 2,4-D, Basagran, or Laddok. See label and
Table 10 for information about possible interactions between this herbicide and soil-applied/foliar insecticides.
Herbicide
Formulation
Product Rate Range
NorthStar
47DF
5 oz
в– в– Not labeled for sweet corn.
в– в– Risk of injury - check with your popcorn seed supplier or chemical representative for sensitivity of inbred/hybrid.
Inbred lines and popcorn hybrids should be thoroughly tested for sensitivity to NorthStar before treating large acreages.
в– в– Apply as a directed spray using drop nozzles when popcorn is between 10 and 30 inches tall. Must be applied
before tassel emergence.
в– в– NorthStar is a premix of primisulfuron (Beacon) plus dicamba (Banvel) for control of most annual broadleaf weeds
and suppression or control of annual and perennial grasses. NorthStar will suppress a number of perennial broadleaf weeds. See Beacon and dicamba descriptions for more information and precautions on use.
в– в– Site of action: group 2 (primisulfuron), group 4 (dicamba). See pages 14-15.
в– в– Apply with NIS (0.25% v/v) or COC (1 to 4 pints/A), but do not use COC if corn is more than 12 inches tall. UAN (2 to
4 quarts/A) or AMS (2 to 4 lbs/A) may also be added.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
Herbicide
Formulation
Product Rate Range
Permit/Sandea/Halomax
75DF
2/3 oz
в– в– These products contain halosulfuron, a translocated sulfonylurea herbicide that controls yellow nutsedge and annual broadleaf weeds, including velvetleaf, ragweeds, cocklebur, and redroot pigweed. Halosulfuron is weak on
lambsquarters and annual morningglories. Does not control ALS-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
87
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Solstice
4L
2.5 - 3.15 oz
Not addressed on label
в– в– Solstice is a premix of fluthiacet-methyl (Cadet) and mesotrione (Callisto) for control of most annual broadleaf weeds
less than 5 inches tall. Solstice should be applied with atrazine whenever possible based on crop size or other
atrazine restrictions.
в– в– Site of action: group 14 (fluthiacet); group 27 (mesotrione). See pages 14-15.
в– в– Can be applied to yellow popcorn and sweet corn up to 30 inches tall, or the V8 stage, whichever occurs first. Sensitivity of popcorn sweet corn hybrids varies widely - check with seed company for information about tolerance of
specific hybrids to Solstice.
в– в– Do not apply to white popcorn or ornamental corn. Allow 40 days between application and harvest of sweet corn
ears or forage.
в– в– Apply with NIS (0.25% v/v). COC can be used instead of NIS to improve control, under dry conditions especially, but
increases the risk of injury. Do not apply with nitrogen-based adjuvants (UAN or AMS), or MSO or MSO blends.
в– в– Apply in a spray volume of 10-30 gpa, and minimum of 15 gpa in dense foliage. Use spray nozzles that provide medium droplet size, and pressure of 35-40 psi at the nozzle. Flat fan nozzles are recommended for optimum coverage.
в– в– Solstice can cause bleaching and speckling of leaves, which is typically short-lived. Spray boom should be kept a
minimum of 18 inches above the crop canopy to ensure uniform spray distribution and to avoid concentrating spray
in corn whorls.
в– в– Do not apply in a mixture with emulsifiable concentrate grass herbicides. See label and Table 10 for information
about possible interactions between this herbicide and soil-applied/foliar insecticides.
Herbicide
Formulation
Product Rate Range
Spirit
57DF
1 oz (1 packet per 4 acres)
в– в– Not labeled for sweet corn.
в– в– Risk of injury - check with your seed supplier or chemical representative for sensitivity of popcorn inbred/hybrid.
в– в– Apply as a directed spray using drop nozzles when popcorn is between 10 and 30 inches tall. Must be applied
before tassel emergence.
в– в– Spirit is a premix of prosulfuron (Peak) plus primisulfuron (Beacon). Mixing with dicamba, 2,4-D, or Buctril/Moxy will
improve lambsquarters control. Most effective control/suppression of perennial broadleaf weeds will occur when
mixed with 2,4-D or dicamba. Spirit is weak on annual morningglories and yellow nutsedge. Does not control ALSresistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Follow these guidelines to avoid carryover of Spirit to subsequent crops: 1) Avoid use where soil pH is greater than
7.8. If used where soil pH is greater than 7.8, plant only field corn or small grains the following year; 2) where less
Popcorn and Sweet Corn
в– в– Can be applied broadcast to popcorn and sweet corn in the spike through layby stage. Two applications are allowed per year, but the second should be applied with drop nozzles. Popcorn and sweet corn hybrids should be
thoroughly tested for sensitivity to halosulfuron before treating large acreages. Do not apply when corn is under
stress from environmental conditions.
в– в– For control of yellow nutsedge, apply 1 to 1 1/3 ounces/A when nutsedge is 4 to 12 inches tall. Dense populations of
nutsedge may require a second application.
в– в– Apply in a minimum spray volume of 10 gpa with NIS (1 to 2 quarts/100 gallons) or COC (1 gallon/ 100 gallons). Include UAN (2 to 4 quarts/A) or AMS (2 to 4 lbs/A) when velvetleaf or redroot pigweed is present.
в– в– Tank mixtures may cause temporary crop injury, especially when the tank-mix partner is Accent or Beacon. Do not
apply in a mixture if the crop is under stress due to drought, water saturated soils, low fertility, hail, frost, insects, or
when the maximum daytime temperature is above 92 degrees.
в– в– Allow 30 days after application before harvesting for forage or grazing.
88
Popcorn and Sweet Corn
Popcorn and Sweet Corn: Postemergence Herbicides—Systemic
than one inch of rain occurs within one month of application, or less than 12 inches of rain occurs within 5 months
after application, plant only corn, small grains, or STS soybean the following year; 2) north of Interstate 80, do not
plant soybeans within 18 months of application; 3) south of interstate 80, soybean can be planted 10 months after
application where soil pH is less than 7.8; and 4) do not apply after June 30. See label for guidelines on rotation to
other crops.
в– в– Apply in a minimum spray volume of 10 gpa. Increasing the volume to at least 20 gpa can improve control in dense
weed infestations.
в– в– Apply with COC (1 to 4 pints/A) or NIS (1 to 2 quarts/100 gallons). UAN (2 to 4 quarts/A) or AMS (2 lbs/A) may be
added to improve control of velvetleaf and other weeds. COC is generally more effective than NIS. Use of a MSO
(Meth Oil, Priority MSO, Sun-It II, for example) may improve control when weeds are large or drought-stressed.
в– в– See label and Table 10 for information about possible interactions between this herbicide and soil-applied/foliar
insecticides.
Herbicide
Formulation
Product Rate Range
Status
56WDG
5 - 10 oz
в– в– Risk of injury - check with your popcorn seed supplier for sensitivity of inbred/hybrid. Not labeled for use on sweet
corn.
в– в– Status is a premix of dicamba plus diflufenzopyr plus a safener, for control of most annual broadleaf weeds. Status
can be weak on velvetleaf, although it is more effective than dicamba alone.
в– в– Site of action: group 4 (dicamba), group 19 (diflufenzopyr). See pages 14-15.
в– в– Status is generally more effective than other dicamba products on perennial broadleaf weeds, and has provided
excellent control of Canada thistle and hedge bindweed in OSU research.
в– в– Apply 5 oz/A when corn is 4 to 36 inches tall, or from V2 to V10. As with any dicamba product, risk of corn injury
increases when corn exceeds 8 to 10 inches in height. To reduce risk of injury, make sure nozzle spacing and spray
boom height are set to minimize interception of spray by the corn plants.
в– в– Apply with NIS (0.25% v/v), COC (1 to 2 pts/A), or MSO (1 to 2 pts/A), plus UAN (at least 1.25% v/v) or AMS (5 -17
lb/100 gallons). To avoid mixing problems, add Status to spray tank before adding AMS.
в– в– Volatility of Status is similar to Clarity. Take precautions to avoid contact of herbicide with sensitive plants via drift or
volatility. Exposure of soybeans to Status via sprayer contamination of spray particle drift with result in more severe
injury compared to other dicamba products.
Herbicide
Formulation
Product Rate Range
Stinger
3L
1/4 - 2/3 pt
в– в– Stinger (clopyralid) is a translocated herbicide that controls ragweeds, cocklebur, jimsonweed, and Canada thistle.
Controls or suppresses Jerusalem artichoke and suppresses sowthistle.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply after corn emergence until popcorn is 24 inches tall or sweet corn is 18 inches tall. Use a spray volume of at
least 10 gallons per acre.
в– в– For annual weed and Jerusalem artichoke control, apply 1/4 to 1/2 pint when weeds have 5 or fewer leaves.
в– в– For Canada thistle control, apply 1/3 to 2/3 pint when thistles are at least 4 inches tall or across, but before the bud
stage. The higher rate provides more complete plant kill and better control of dense patches. Do not cultivate prior
to or for 14 to 20 days following application.
89
Popcorn: Harvest Aid
Attribute Bt11 Sweet Corn (glufosinate-resistant)
Herbicide
Liberty 280SL
Formulation
2.34L
Product Rate Range
20 oz
в– в– Liberty (glufosinate) is a contact, broad-spectrum herbicide for postemergence use only on Attribute Bt11 (glufosinate-resistant) sweet corn hybrids.
в– в– Site of action: group 10 (see pages 14-15).
в– в– Apply broadcast from corn emergence through 24-inch corn or the V7 stage (7 collars), whichever occurs first. Can
be applied twice during the same season, for a maximum total of 40 oz/A. Allow at least 10 days between appliocations, and 50 days between the last application and harvest of ears.
в– в– Liberty should be used in a combined preemergence plus postemergence program, where the preemergence herbicide will provide control of grass and broadleaf weeds for several weeks to a month after corn planting. Postemergence applications of Liberty in this program should include atrazine or Laudis where possible. Liberty is weak
on yellow foxtail, barnyardgrass, and lambsquarters, and the other PRE or POST herbicides used with Liberty should
provide substantial control of these weeds.
в– в– Maximum height for grass weeds: barnyardgrass, crabgrass, yellow foxtail, fall panicum - 3 inches; woolly cupgrass, shattercane, and green, giant, and robust foxtails - 6 inches; volunteer corn - 10 inches. Yellow foxtail and
crabgrass should be treated prior to tiller initiation for best results. Liberty is most effective on volunteer corn
(including glyphosate-resistant) that is 6 to 12 inches tall.
в– в– Maximum height for broadleaf weeds: velvetleaf, pigweeds - 3 inches; lambsquarters, waterhemp - 4 inches; burcucumber, cocklebur, annual morningglories, black nightshade, ragweeds, and Pennsylvania smartweed - 6 inches.
в– в– Apply with AMS at the rate of 3 lbs/A, or 17 lbs/100 gallons. When air temperatures are above 85 degrees, the rate
can be reduced to 1.5 lbs/A, or 8.5 lbs/100 gallons, to reduce the risk of leaf burn. Applying with surfactants or crop
oils may increase the risk of crop injury.
в– в– Apply in a spray volume of 15 to 20 gpa. Liberty should be applied with a nozzle type and spray pressure that results in medium spray droplets (250 to 350 microns).
в– в– Liberty is most effective when applied under warm, sunny conditions. Effectiveness may be reduced if applied
when heavy dew, fog and mist/rain are present, or if weeds are under stress due to drought, cool temperatures,
or extended periods of cloudiness. To avoid reduced weed control, apply between dawn and two hours before
sunset.
Popcorn and Sweet Corn
Herbicide
Formulation
Product Rate Range
Aim
2EC
1 - 2 oz
в– в– Aim (carfentrazone) can be applied prior to harvest of corn for dessication of velvetleaf, morningglory, pigweeds,
and other weeds. Apply at least 3 days before harvest when the crop is mature and grain has begun to dry down.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Use a spray volume that results in complete coverage of foliage. Apply with NIS (0.25% v/v) or COC (1 to 2% v/v).
UAN or AMS may also be added.
90
Popcorn and Sweet Corn
Roundup Ready Sweet Corn (glyphosate-resistant)
Herbicide
Formulation
Product Rate Range
Glyphosate
Various - see Table 24
0.55 - 1.5 lb ae/A
в– в– Glyphosate is a translocated herbicide that controls emerged annual and perennial grass and broadleaf weeds.
Table 24 contains a list of currently available glyphosate products. Variations in the formulation may result in difп»їferences in product rate and adjuvant recommendations, and specified rainfast intervals. Users should consult labels
and local product use guides for more specific information.
в– в– Apply postemergence only to glyphosate-resistant sweet corn hybrids (Roundup Ready).
в– в– Site of action: group 9 (see pages 14-15).
в– в– The rate in a single application should not exceed 1.5 lb ae/A, and the total applied between emergence and 48
inches should not exceed 4.5 lbs ae/A. The general recommendation on most labels for the initial postemergence
glyphosate application is a rate of 0.56 to 0.75 lbs of glyphosate acid per acre (lbs ae/A) when weeds are less than
4 inches tall, or before weeds become competitive with the crop. Rates should be increased to 1.1 to 1.5 lbs ae/A
where weeds are more than 6 inches tall.
в– в– Apply from corn emergence through the 8-collar stage or until corn is 30 inches tall, whichever occurs first. When
corn is 24 to 30 inches tall, use of drop nozzles will generally improve spray coverage on weeds. For sweet corn
heights of 30 to 48 inches, avoid treating if corn has reached the reproductive stage, and apply only with drop
nozzles adjusted to keep spray out of corn whorls.
в– в– Glyphosate resistance has developed in populations of marestail, Palmer amaranth, waterhemp, and common
and giant ragweed in Ohio, Indiana, and Illinois. Consider use of a preemergence herbicide that provides residual
control of these weeds, avoid use of herbicide programs consisting solely of multiple glyphosate applications, and
include another postemergence herbicide where necessary to improve control.
в– в– Control of perennial weeds will require higher rates than annual weeds. Application when perennials are in the bud
to bloom stage (or boot to seedhead for grasses) will provide the most complete control of the entire plant. Minimum size of various perennial weeds for most effective control through the growing season: quackgrass, Canada
thistle, wirestem muhly, and yellow nutsedge - 6 inches; field bindweed and common milkweed -12 inches; johnsongrass and hemp dogbane - 18 inches.
в– в– Apply in a spray volume of 5 to 20 gpa. Allow 30 days between application and harvest.
91
Soybean Herbicide Management Strategies
continue to emerge after the POST application and are
not suppressed by the soybean leaf canopy, a second
POST application may be needed.
A planned PRE plus POST approach will provide
more consistent weed control than any one-pass approach in many fields, and help solve some of the
problems in management of glyphosate and other POST
herbicides. The most complete PRE plus POST program includes use of a PRE herbicide with activity on
key broadleaf weeds that also provides at least some
early-season control of grasses, followed by glyphosate in Rounudp Ready soybeans, or another POST
treatment with activity on grass and broadleaf weeds
in non-Roundup Ready soybeans. The PRE herbicide
can control or reduce the population of some problem
broadleaf weeds, such as lambsquarters, waterhemp,
and giant ragweed, making it relatively easy to control
any later-emerging weeds with the POST treatment.
A major advantage of the PRE plus POST approach,
compared to total POST, is that the PRE herbicide will
often provide enough weed control to prevent major
problems if weather delays the POST application. The
PRE plus POST approach can allow for a slightly delayed
POST application, resulting in more consistent control
of late-emerging weeds such as foxtails, giant ragweed,
black nightshade, waterhemp, and perennials.
Preemergence (PRE) Soybean
Herbicide Programs
Total PRE herbicide programs fit fields with:
в– в– low annual grass populations
в– в– low to moderate populations of annual broadleaf
weeds, including common ragweed, smartweed,
pigweed, and velvetleaf
в– в– most populations of lambsquarters
Total PRE programs do not fit fields with:
в– в– moderate to high annual grass populations
в– в– giant ragweed, Palmer amaranth, cocklebur, burcucumber, annual morningglory, or waterhemp
в– в– biennial and perennial weeds
Advantages:
в– в– one-pass, can apply while planting
в– в– with adequate rain, provides control through the
first 6 weeks, and later-emerging weeds have much
reduced impact on soybean yields
Soybeans
A number of broad-spectrum preemergence (PRE)
and postemergence (POST) herbicides are available
for use in soybeans. In OSU research, almost any type
of approach to herbicide management can be used in
fields with low weed pressure with little risk of crop yield
loss. These approaches include: total PRE, PRE followed by POST, and total POST. However, the biology
of some weeds that occur in soybean fields, in addition
to the slow early development of no-till soybeans, can
make it difficult to achieve effective weed control with a
single application of PRE or POST herbicides. For this
reason, a PRE followed by POST program or a twopass POST program often provides the most consistent
control.
Weeds that are especially problematic in a total PRE
herbicide program, depending upon their population,
include annual grasses, giant ragweed, ALS-resistant
common ragweed, marestail, annual morningglory, cocklebur, waterhemp, and most perennial weeds. Another
major drawback to PRE herbicides applied at planting
is the narrow window of time in which at least 0.5 to 1
inch of rain must occur to move herbicide into the soil.
In early May when soybeans are often planted, weeds
will typically start to emerge within 8 to 10 days after
tillage or an application of glyphosate or paraquat. Rain
is needed before these weeds emerge in order for PRE
herbicides to be effective. Applying herbicides several
weeks or more before planting of no-till soybeans often
results in more consistent weed control initially, although
herbicide activity may not last as long after planting,
compared to application at the time of planting.
Weeds that can be problematic in a one-pass, total
POST herbicide program, depending upon their population, include annual grasses, giant ragweed, waterhemp,
lambsquarters, marestail, and some perennials (because
they may be too small at the time of an early POST application). Most POST soybean herbicides should be
applied before weeds exceed 3 to 6 inches in height for
consistent control and to avoid crop yield loss. Glyphosate application can be timed for weed heights of 4 to
8 inches, although velvetleaf, lambsquarters and some
other weeds are more easily controlled when less than
6 inches tall. Problems with proper timing of a single
postemergence application include: 1) giant ragweed
grows at approximately twice the rate of most annual
weeds, and is likely to be 8 to 12 inches tall when other
weeds are 3 to 6 inches tall; 2) wet and/or cold weather
can prevent timely application and result in the need to
treat many acres within a short period of time once favorable weather returns, and 3) when weed populations
92
Disadvantages:
в– в– dependence upon adequate rain within narrow period of time
в– в– not effective enough on tough broadleaf or perennial
weeds or in moderate to high grass populations
в– в– soybeans need to be competitive earlier in season
compared to PRE plus POST programs
Approaches:
Soybeans
The most broad-spectrum programs include mixtures
of a grass herbicide (Command, metolachlor, Outlook,
pendimethalin, etc) with Canopy, Gangster, Envive, Valor
XLT, Scepter, Sonic, or Authority First. Python, Valor, and
metribuzin have less activity on giant ragweed and other
tough broadleaf weeds compared to the previously
listed products.
Preemergence (PRE) plus Postemergence (POST) Soybean Herbicide Programs
PRE plus POST herbicide programs fit any field, but
are especially well-suited for fields with:
в– в– moderate to high annual grass populations
в– в– moderate to high giant ragweed, cocklebur, and annual morningglory populations
в– в– Palmer amaranth and waterhemp
в– в– biennial and perennial weeds
в– в– burcucumber
в– в– no-tillage
Advantages:
в– в– very consistent, as long as some rain on PRE
в– в– creates wider window for POST application, compared to total POST programs
в– в– good on many tough weeds
в– в– best approach to control of herbicide-resistant weeds
Disadvantages:
в– в– dependence upon rain for PRE activity (although
have planned POST backup)
в– в– two-pass
Approaches:
In fields with low grass populations, using PRE grass
or grass plus broadleaf herbicides followed by POST
broadleaf herbicide is one approach. Examples:
в– в– Dual II Magnum followed by Flexstar + thifensulfuron
в– в– Prowl followed by Pursuit + Cobra
In fields with moderate to high grass populations, using a PRE broadleaf herbicide that also has some grass
activity followed by a POST grass or grass plus broad-
leaf herbicide treatment is another approach. Choice
of PRE herbicide would vary with type of broadleaf
weeds present – problem weeds such as giant ragweed
require PRE use of Canopy EX, Synchrony XP, FirstRate,
Gangster, or Scepter. Examples:
в– в– Canopy followed by Flexstar + Fusion
в– в– Valor XLT followed by glyphosate (RR soybeans)
в– в– Matador followed by Liberty (LibertyLink soybean)
Total Postemergence (POST) Soybean Herbicide Programs
Total POST herbicide programs (one application)
can be used in fields with:
в– в– low to moderate populations of most annual weeds
в– в– low populations of giant ragweed
Avoid use in fields with:
в– в– в– в– в– в– в– в– moderate to high lambsquarters or grass populations
high giant ragweed populations
marestail
late-season perennials such as hemp dogbane
Advantages:
в– в– one-pass, can plant first and apply later (except for
burndown in no-till soybeans)
в– в– not dependent upon rainfall for postemergence
activity (although soil moisture status affects weed
response to herbicides)
в– в– consistent control of low to moderate annual weed
populations
Disadvantages:
в– в– narrow window of application depending upon
weather should be applied before weeds exceed
about 6 inches in height to avoid yield loss
в– в– a second POST application may be needed for lateemerging weeds that are not suppressed by the
soybean leaf canopy
в– в– application may be too early for best perennial weed
control
в– в– Difficult to control herbicide-resistant weeds without
the use of PRE herbicides
Approaches:
Apply a POST herbicide treatment with activity on
grass and broadleaf weeds before weeds exceed 3 to
6 inches in height (4 to 8 inches for Roundup Ready
soybean program). Make a second POST application as
necessary for late-emerging weeds.Examples:
Glyphosate (Roundup Ready soybeans)
Flexstar + Harmony GT + Fusion
Raptor
93
Table 13. Weed Response to Preplant/Preemergence Herbicides in Soybeans—Grasses
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for more information on herbicide site of action classification and description of site of action groups.
Weed control rating: 9 = 90% to 100% control
8 = 80% to 90% control
7 = 70% to 80% control
6 = 60% to 70% control
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
Crop tolerance rating:
0 = Excellent
1 = Good
2 = Fair
3 = Poor
Yellow Nutsedge
Woolly cupgrass
Seedling Johnsongrass
Shattercane
Yellow Foxtail
Giant Foxtail
Field sandbur
Fall Panicum
Crabgrass
Barnyardgrass
Crop Tolerance
Site of Action
Grasses
Soybeans
Preplant Incorporated Only
Trifluralin
3
1
9
9
9
8+
9
9
7
7
8+
Preplant or Preemergence
Authority Assist
2/14
2
6
7
7
7
7
6
6
8
Authority First/Sonic
2/14
2
7
Authority MTZ
5/14
2
6
Authority MAXX/XL
2/14
2
8
Boundary/Ledger/Tailwind
5/15
1
8
9
8+
6
8+
8+
7
8
Canopy DF/Cloak DF
2/5
2
Canopy/Cloak EX, Fallout
2
2
Command
13
0
9
9
9
7
9
9
6
6
7
Envive/Enlite
2/14
2
Fierce3
2
8
8
8
6
8
8
6
Fierce XLT
2/14/15
2
8
8
8
6
8
8
6
FirstRate
2
0
Flumioxazin
14
2
Gangster/Surveil
2/14
2
Intimidator
5/14/15
1
8
9
8+
6
8+
8+
7
8
Latir
2/14
2
6
7
7
7
7
6
6
Lorox
7
2
Matador
2/5/15
1
9
9
8+
6
8+
8+
7
8
Metolachlor/s-metolachlor1
15
1
8
9
8+
6
8+
8+
7
8
Metribuzin
5
2
6
5
6
6
6
Optill PRO
2/14/15
2
8
8
8
8
8
6
6
6
Outlook
15
1
8
9
8
6
8
8
7
8
Pendimethalin
3
2
8
9
9
8
8
8
7
7
8+
Prefix/Vise/Statement3
14/15
1
8
8
8
6
8
8
7
Pursuit
2
1
6
7
7
7
7
6
6
Pummel
2/15
1
9
9
9
6
9
9
7
8
Python
2
1
Scepter
2
1
6
Spartan
14
2
7
7
7
7
7
8
Torment
2/14
1
6
7
7
7
7
6
6
Trivence
2/5/14
2
Valor XLT
2/14
2
Warrant
15
1
8
8
8
7
8
8
7
7
Zidua, Anthem
15
1
8
8
8
6
9
8
6
1Warrant is labeled only for POST use in soybeans, and provides residual weed control only (does not control emerged weeds).
2Marestail ratings are for residual control only (not burndown), and are based on a weedfree start at planting through use of an effective burndown treatment.
3PRE rates are not intended to provide season-long control. Should be used only where it will be followed with a broad-spectrum POST herbicide treatment (such as glyphosate in Roundup Ready soybeans or Ignite on Liberty Link soybeans).
94
Table 14. Weed Response to Preplant/Preemergence Herbicides in Soybeans—Broadleaf Weeds
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may be better or worse than indicated in the table, due to weather or soil conditions or
other variables. See pages 14-15 for more information on herbicide site of action classification and description of site of action groups.
Weed control rating: 9 = 90% to 100% control
8 = 80% to 90% control
7 = 70% to 80% control
6 = 60% to 70% control
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
Crop tolerance rating:
0 = Excellent
1 = Good
2 = Fair
3 = Poor
Soybeans
Preplant Incorporated Only
Trifluralin
7+
8+
8+
8
9
8
Preplant or Preemergence
Authority Assist
8+
9
7
6
8
9
9
9
8
8
8+
9
9
8
8+
Authority First/Sonic
8+
8
8
9
7
8
9
9
9
9
8
8+
9
9
8
8+
Authority MTZ
7
8
6
9
9
8
8
8
8
9
9
7
8
Authority MAXX/XL
8+
8
8
9
7
9
9
9
9
9
8
8+
9
9
8+
8+
Boundary/Ledger/Tailwind
3
8
6
6
6
6
8
6
6
6
7+
9
8
6
7+
Canopy DF/Cloak DF
7+
6
8
9
7
9
7
9
9
9
6
6
9
9
8+
6
Canopy/Cloak EX, Fallout
7+
6
8
9
7
9
7
9
9
9
9
9
8+
Command
6
6
7
7
8
9
9
9
8
9
Envive/Enlite
8
9
6
8
9
7
7
9
8
9
9
9
8
8+
9
9
8+
8+
Fierce3
7
9
8
8
6
7+
9
9
8
8
9
9
7
7
9
Fierce XLT
8
9
6
8
9
7
7
9
7+
9
9
9
8
9
9
9
8+
9
FirstRate
7+
8
9
7
9
9
9
9
8
8+
Flumioxazin
7+
9
7
7
7+
9
9
8
8
8+
9
7
7
8+
Gangster/Surveil
8
9
8
9
7
7
9
8
9
9
9
8
8+
9
9
8+
8+
Intimidator
9
8
8
7+
9
7
6
6
8
9
9
6
8
Latir
8
9
7
8
7
6
8
9
9
9
8
8
8+
9
9
9
8+
Lorox
7
6
8
8
8
6
6
9
9
7
9
9
6
7
Matador
7
9
7
7
8
8
9
9
6
7
9
9
8
7
Metolachlor/s-metolachlor1
8
6
6
7
8
7
Metribuzin
6
6
6
7
8
9
8
8
7+
9
9
7
7+
Optill PRO
7
9
7
7
8
8
9
9
7
7
9
9
9
7
Outlook
8
6
6
7+
8
7+
Pendimethalin
7+
8+
8+
7
9
7
Prefix/Vise/Statement3
8
8
8
7
7
8
8
8
Pursuit
7
9
7
6
6
8
8
9
9
9
9
8
Pummel
7
9
7
6
6
8
8
9
9
7
9
9
8
7
Python
8
7
7
7
8
9
9
9
8
8+
Scepter
7
9
6
8
8
7
9
9
9
6
9
9
7
Spartan
8
9
8+
9
9
8
8
8+
9
8
7
8+
Torment
7
9
7
8
8
6
8
8
9
9
6
9
9
8
6
Trivence
8
9
6
8
9
7
7
9
8+
9
9
9
8
9
9
9
8+
9
Valor XLT
8
9
6
8
9
7
7
9
7+
9
9
9
8
8+
9
9
8+
8+
Warrant
8
8
8
8
8
6
8
Zidua, Anthem
8
7
7
7
8
8
8
8
8
7
8
1Warrant is labeled only for POST use in soybeans, and provides residual weed control only (does not control emerged weeds).
2Marestail ratings are for residual control only (not burndown), and are based on a weedfree start at planting through use of an effective burndown treatment.
3PRE rates are not intended to provide season-long control. Should be used only where it will be followed with a broad-spectrum POST herbicide treatment (such as
glyphosate in Roundup Ready soybeans or Ignite on Liberty Link soybeans).
Waterhemp (group 2+14-R)
Waterhemp (group 2-R)
Velvetleaf
Smartweed
Pigweed (redroot/smooth)
Palmer Amaranth (group 2-R)
Marestail (group 2+9-R)2
Marestail (group 9-R)2
Lambsquarters (group 5-R)
Lambsquarters
Kochia
Jimsonweed
Giant Ragweed (group 2-R)
Giant Ragweed
Common Ragweed (group 2+9-R)
Common Ragweed (group 2-R)
Common Ragweed
Cocklebur
Burcucumber
Black Nightshade
Annual Morningglory
Broadleaf Weeds
8
6
7+
6
7
7
7
7
7
7
7+
7+
7
7
7
6
6
8
8
95
Table 15. Grasses and Nutsedge—Response to Postemergence Herbicides in Soybeans
This table compares the relative effectiveness of herbicides on individual weeds. Ratings indicate the level of control of weeds
present at the time of application, and are based on labeled rate and weed size or growth stage. Postemergence soybean herbicides not listed on the grass or broadleaf section of this table lack significant activity on those weeds. Performance may be better or
worse than indicated in the table, due to weather or soil conditions or other variables.
Crop Tolerance
Barnyardgrass
Crabgrass
Fall Panicum
Field Sandbur
Giant Foxtail
Yellow Foxtail
Shattercane
Seedling Johnsongrass
Rhizome Johnsongrass
Quackgrass
Volunteer Corn
Vol Corn (glyphosate-resistant)
Wirestem muhly
Yellow nutsedge
Woolly cupgrass
6
1
-
-
-
-
-
-
-
-
-
-
-
-
-
8+
-
10/14
2
6
8
8
8
8+
6
8
8
7
6
7
7
6
-
6
2
2
-
-
-
-
-
-
-
-
-
-
-
-
-
8
-
Extreme/Tackle2
2/9
1
9
8+
9
9
9
9
9
9
8+
8+
9
-
8
7
9
Flexstar GT2
9/14
2
9
9
9
9
9
9
8
9
9
9
9
-
8+
8
9
Glyphosate 0.75 lb ae/A2
9
0
8+
8+
8+
9
9
9
8
9
9
9
9
-
8+
7
9
Glyphosate 1.5 lb2
9
0
9
9
9
9
9
9
8
9
9
9
9
-
9
8
9
Liberty/Cheetah3
10
0
6
8
8
6
8
6
8
8
7
6
7
7
6
-
8
Pursuit/Torment
2
1
6
7
7
-
8
7
8
8
-
-
-
-
-
-
-
Raptor
2
2
6
7
7
7
8+
7
-
-
-
-
8
8
-
-
-
Storm
Postemergence
Basagran/Broadloom
Cheetah Max3
Classic
6/14
2
-
-
-
-
-
-
-
-
-
-
-
-
-
7
-
Synchrony XP1
2
0
-
-
-
-
-
-
-
-
-
-
-
-
-
8
-
Assure II/Targa
1
0
8+
8+
9
9
9
8
9
9
9
9
9
9
6
-
8
Clethodim
1
0
9
8+
9
9
9
9
9
9
9
9
9
9
8+
-
9
Fusilade DX
1
0
8
8
8
8
8
8
9
9
9
9
9
9
8+
-
8
Fusion
1
0
9
8+
9
8+
9
9
9
9
9
9
9
9
8+
-
8
Poast/Poast Plus
1
0
9
8
9
9
9
9
8
8
7
7+
8
8
-
-
9
1Ratings are for 0.75 oz/A applied to STS soybeans.
2Apply to Roundup Ready soybeans only.
3Apply to Liberty Link soybeans only
Soybeans
Site of Action
Weed control rating: Crop tolerance rating:
9 = 90% to 100% control
0 = Excellent
8 = 80% to 90% control
1 = Good
7 = 70% to 80% control
2 = Fair
6 = 60% to 70% control
3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
96
Table 16. Broadleaf Weeds—Response to Postemergence Herbicides in Soybeans
This table compares the relative effectiveness of herbicides on individual weeds. Ratings indicate the level of control of weeds
present at the time of application, and are based on labeled rate and weed size or growth stage. Performance may be better or
worse than indicated in the table, due to weather or soil conditions or other variables.
Crop Tolerance
Annual Morningglory
Black Nightshade
Burcucumber
Cocklebur
Common Ragweed
Common ragweed (group 2-R)
Common ragweed (group 9-R)
Com ragweed (group 2+9-R)
Common ragweed (group 2+14-R)
Giant Ragweed
Giant ragweed (group 2-R)
Giant ragweed (group 9-R)
Giant ragweed (group 2+9-R)
Jimsonweed
Kochia
Lambsquarters
Lambsquarters (group 5-R)
Palmer amaranth (group 2-R)
Palmer amaranth (group 2+9-R)
Pigweed (redroot/smooth)
Marestial (group 9-R)
Mareastail (group 2+9-R)
Smartweed
Velvetleaf
Waterhemp (group 2-R)
Waterhemp (group 2+9-R)
Waterhemp (group 2+9+14-R)
Postemergence
Aim
Basagran/
Broadloom
Cadet, Anthem
Cheetah Max3
Classic
Cobra/Phoenix
Extreme/Tackle2
FirstRate
Flexstar/Rhythm
Flexstar GT2
Glyphosate 0.75 lb2
Glyphosate 1.5lb2
Liberty/Cheetah3
Marvel
Prefix/Vise
Pursuit
Raptor
Reflex/Dawn
Resource
Storm
Synchrony XP1
Thifensulfuron
Torment
Ultra Blazer
Site of Action
Soybeans
Weed control rating: Crop tolerance rating:
9 = 90% to 100% control 0 = Excellent
8 = 80% to 90% control
1 = Good
7 = 70% to 80% control
2 = Fair
6 = 60% to 70% control
3 = Poor
- = less than 60% control, not recommended.
Crop injury of 1 or less is rarely significant.
14
2
8
8
-
-
6
6
6
6
-
-
-
-
-
-
-
7
7
-
-
8
-
-
-
-
-
-
6
1
-
-
-
9
7
7
7
7
7
6
6
6
6
9
7
7
7
-
-
-
-
-
9 8+ -
-
-
14
10/14
2
14
2/9
2
14
9/14
9
9
10
14
14/15
2
2
14
14
6/14
2
2
2/14
14
2
2
2
3
1
1
2
2
0
0
0
2+
2
1
2
2
2
2
0
2+
2
2
7
9
7
7
8
8
8
9
6
7
8
9
8
7
7
8
6
8+
8
8
8
9
8+
9
9
9
8
9
9
7
8
9
9
8
7
9
8
8
8+
7
8
8+
7
8
8
8
8
6
6
6
6
6
6
8+
7
6
9
9
8
9
9
8+
9
9
9
9
7
8+
9
8
7
7
8+
9
6
8+
7
9
8
9
8+
9
9
9
8+
9
9
7
8+
6
7
8+
7
9
8
9
9
9
9
8+
9
9
8+
9
9
7
8+
8+
7
9
8+
9
9
8
9
7
9
9
9
9
7
8+
6
7
8+
7
9
8
9
9
9
9
9
9
9
7
8+
8+
7
9
8+
9
9
8+
9
8+
9
9
5
-
9
7+
8
8+
9
8
9
8
8+
8+
6
8
7
8
8
7+
7+
8
7
9
8
8+
8
9
8
8+
8+
6
8
8
7+
8
7
9
7+
8
6
9
8
8
8+
6
8
7
8
8
7+
7+
8
7
9
8
8
8
8+
6
8
8
7+
8
7
9
8+
9
9
8
9
9
9
9
9
8
9
8+
8
9
7
9
9
9
9
6
8+
7
8
6
8
8
8+
8
7
7+
7+
6
6
7+
6
7
7
8+
6
8+
8
8+
7
7
6
8
7
6
8
8
6
-
7 - 7 8+ 8+
- - 8 8
8+ 8 - - 7 8 8
8+ 9 8
8 8 8+ 9 7 8 8
7 7 7
- 8 8
6 - 8 - - 8 8
7 - 6 7 7
8 - 8 - 6 8 8
- 8 8
8
9
9
9
9
9
9
9
9
8
9
9
9
9
9
7
9
9
9
9
9
8
8
8
8
8
-
8
8
-
9
8
6
9
8
9
9
8
9
9
8
7
9
8
7
9
9
8
9
9
1Ratings are for 0.75 oz/A applied to STS soybeans.
2Apply to Roundup Ready soybeans only.
3Apply to Liberty Link soybeans only.
9
9 - 9 8+ 8+
8 - 7 8 8
9 8 9 - 8 8 8
9 9 8
8 8 9 9 8 8 8
9 7 7
6 8 8
9 - 9 - 6 8 8
9 - 8 7 7
9 - 9 - 9 8 8
6 8 8
8
8
-
97
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
Afforia
50.8DG
2.5 to 3.75 oz
в– в– Afforia is a premix of flumioxazin (Valor etc), tribenuron (Express), and thifensulfuron (Harmony) for control of
broadleaf weeds, including lambsquarters, pigweeds, black nightshade, and marestail, and partial control/suppression of Pennsylvania smartweed, waterhemp, Palmer amaranth and velvetleaf. This product does not control giant
ragweed. The tribenuron and thifensulfuron have activity on emerged weeds,but the residual control is due to the
flumioxazin.
в– в– Site of action: group 14 (flumioxazin); group 2 (tribenuron, thifensulfuron). See pages 14-15.
в– в– Can be applied in fall or spring, with following restriction: the 2.5 oz rate should be applied at least 1 day before
planting; rates greater than 2.5 oz should be applied at least 7 days before planting. When used on coarse-textured soils or high pH (>7.9) soil, extend time between application and planting by another 7 days.
в– в– Do not apply to frozen or snow-covered ground. Do not till after fall applications.
в– в– Soybean stunting may occur when rainfall results in prolonged wet soil conditions following application. Excessive
rainfall shortly after soybean emergence can result in minor leaf necrosis or crinkling, or loss of lower leaves. Risk
of injury can be minimized by not using this product on poorly-drained soils, ensuring that seeds are completely
covered with soil, and applying a week or more prior to planting.
Herbicide
Formulation
Authority MTZ
45DG
в– в– Authority MTZ is a premix of metribuzin and sulfentrazone (Spartan) for control or suppression of broadleaf weeds,
including lambsquarters, pigweeds, black nightshade, Pennsylvania smartweed, velvetleaf, and waterhemp. This
product does not control giant or common ragweed or cocklebur.
в– в– Site of action: group 14 (sulfentrazone); group 5 (metribuzin). See pages 14-15.
в– в– Application rates when used in standard PRE or PRE + POST programs, on soils with 2 to 4% OM: coarse-textured
- 14 to 16 oz; medium-textured - 16 to 18 oz; fine-textured - 18 to 20 oz. Application rate when followed by a POST
application of glyphosate in Roundup Ready soybeans, on soils with 2 to 4% OM: coarse-textured - 8 to 10 oz;
medium-textured - 10 to 12 oz; fine-textured - 12 to 14 oz.
в– в– Can be applied from 30 days before planting through 3 days after planting. To minimize risk of crop injury, apply a
week or more prior to planting. When applied after planting, apply prior to soybean seed germination to prevent
injury to emerging soybean seedlings.
Soybeans
Herbicide
Formulation
Product Rate Range
Authority Assist
4L
4 to 12 oz
в– в– Authority Assist is a premix of imazethapyr (Pursuit) and sulfentrazone (Spartan) for control or suppression of broadleaf weeds, including lambsquarters, pigweeds, black nightshade, Pennsylvania smartweed, velvetleaf, annual
morningglory, and waterhemp. Provides partial control of annual grasses, but a follow up postemergence application will be necessary for complete grass control. This product does not control common or giant ragweed.
в– в– Site of action: group 14 (sulfentrazone); group 2 (imazethapyr). See pages 14-15.
в– в– Application rates when used in standard PRE or PRE + POST programs, on soils with 2 to 4% OM: coarse-textured
- 8 to 10 oz; medium-textured - 10 to 12 oz; fine-textured - 12 oz. Application rate when followed by a POST application of glyphosate in Roundup Ready soybeans, on soils with 2 to 4% OM: coarse-textured - 4 to 5 oz; medium-textured - 5 to 6 oz; fine-textured - 6 oz. Within a rate range, use higher rates where soil pH is less than 7, and lower
rates where soil pH is greater than 7.
в– в– Can be applied from 45 days before planting through 3 days after planting. To minimize risk of crop injury, apply a
week or more prior to planting. When applied after planting, apply prior to soybean seed germination to prevent
injury to emerging soybean seedlings.
в– в– Do not use on coarse soils with less than 1% organic matter, or to soils with pH greater than 7.5. Do not incorporate
deeper than 2 inches.
98
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Soybeans
в– в– Do not apply to sandy soils with less than 1% organic matter, or to soils with pH greater than 7.5. Do not apply to
frozen soil or incorporate deeper than 2 inches.
Herbicide
Formulation
Authority XL
70DF
Authority MAXX
66DF
в– в– Authority XL and MAXX are premixes of chlorimuron (Classic) and sulfentrazone (Spartan) for control or suppression of most annual broadleaf weeds. This product does not control group 2-resistant ragweeds, but does provide
residual control of group 2-resistant marestail, waterhemp, and Palmer amaranth. The ratio of sulfentrazone to chlorimuron is higher in Authority MAXX compared with Authority XL.
в– в– Site of action: group 14 (sulfentrazone); group 2 (chlorimuron). See pages 14-15.
в– в– Can be applied in fall, or in spring from 60 days before through 3 days after soybean planting, but before emergence. To minimize risk of crop injury, apply a week or more prior to planting. When applied after planting, apply
prior to soybean seed germination to prevent injury to emerging soybean seedlings.
в– в– Authority XL/MAXX application rates on soils with 2 to 4% OM: coarse-textured - 6 to 7 oz; medium-textured - 7 to
8 oz; fine-textured - 8 to 9.6 oz. Authority XL application rate when followed by a POST application of glyphosate in
Roundup Ready soybeans or Liberty in LibertyLink soybeans, on soils with 2 to 4% OM: coarse-textured - 3.2 to 4
oz; medium-textured - 3.2 to 4.8 oz; fine-textured - 4 to 5 oz.
в– в– Do not apply Authority XL on soils with pH greater than 7.6. Authority XL rates are not pH-dependent, but rotation
intervals for all crops except small grains are extended to at least 18 months for soil pH between 7.2 and 7.6, regardless of rate. Authority MAXX rotation intervals are not pH-dependent.
Herbicide
Formulation
Product Rate Range
Boundary/Ledger/Tailwind
6.5E
1.5 to 3 pts
в– в– Premix of s-metolachlor plus metribuzin for annual grass and broadleaf control in soybeans. Controls most annual
grasses, lambsquarters, pigweeds, waterhemp, black nightshade, and Pennsylvania smartweed. See metribuzin and
s-metolachlor descriptions for guidelines on use.
в– в– Site of action: group 5 (metribuzin), group 15 (s-metolachlor). See pages 14-15.
в– в– Application rates can be reduced to 1.5 to 1.8 pts/A when part of a planned preemergence followed by postemergence program.
Herbicide
Formulation
Product Rate Range
Canopy EX/Cloak EX/Fallout
29.5DF
1.1 to 3.3 oz
Synchrony XP
28.4WDG
1 to 3 oz
Canopy/Cloak DF
75DF
2.25 to 7 oz
в– в– Canopy EX is a premix of chlorimuron (Classic) plus tribenuron (Express), also available as Cloak EX and Fallout;
Synchrony XP is a premix of chlorimuron plus thifensulfuron (Harmony GT); and Canopy/Cloak DF is a premix of
chlorimuron plus metribuzin. These herbicides provide residual control of ragweeds, annual morningglory, cocklebur, velvetleaf, Pennsylvania smartweed, pigweeds, and lambsquarters. Control of cocklebur, morningglory, and
giant ragweed varies with rainfall and population. Early preplant application will provide most effective control of
giant ragweed.
в– в– Canopy EX and Synchrony XP do not control group 2-resistant weeds. High rates of Canopy/Cloak DF can provide
limited residual control of group 2-resistant waterhemp, pigweed, and marestail, but additional metribuzin will usually be needed for acceptable control of these weeds.
в– в– Site of action: group 5 (chlorimuron, tribenuron, thifensulfuron); group 5 (metribuzin). See pages 14-15.
в– в– Canopy EX can be applied in fall or spring, with following restriction: rates of 2.2 oz or less should be applied at
least 7 days before planting; rates of 2.2 to 3.3 oz should be applied at least 14 days before planting. Canopy/Cloak
99
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
в– в– в– в– в– в– в– в– в– в– DF can be applied in fall or spring (no more than 45 days before planting). Synchrony can be applied preplant or
preemergence in the spring, no more than 45 days before planting.
Maximum rate on soils where the composite pH exceeds 7.0: Canopy EX - 1.1 oz/A; Canopy/Cloak DF - 2.25 oz/A;
Synchrony XP - 1 oz/A.
The chlorimuron component helps control many emerged no-till weeds in mixtures with 2,4-D and glyphosate in
spring preplant burndown treatments.
Apply with COC (1 gallon/100 gallons spray) for best control of emerged weeds, unless glyphosate is included in the
treatment.
Canopy/Cloak products can be applied to no-till or conservation tillage fields in the fall for burndown of existing
vegetation and limited residual control into the following growing season. 2,4-D should be included with all fallapplied treatments. Do not apply to frozen ground.
Soybean stunting may occur when rainfall results in prolonged wet soil conditions following application.
Herbicide
Formulation
Product Rate Range
Envive
41.3 DG
2.5 - 5.3 oz
Enlite
47.9 DG
2.8 - 4.25 oz
в– в– Envive and Enlite are premixes of chlorimuron (Classic) plus thifensulfuron (Harmony GT) plus flumioxazin (Valor) for
residual control of most annual broadleaf weeds. The ratio of chlorimuron to the other ingredients is lower in Enlite
than Envive, allowing use of Enlite over a broader range of soil pH levels. Maximum Envive rate on soils where the
composite pH exceeds 7.0 is 2.5 oz. The Enlite rate is not pH-dependent.
в– в– Control of cocklebur, morningglory, and giant ragweed varies with rainfall and population. Early preplant application
will provide most effective control of giant ragweed.
в– в– Will not control group 2-resistant giant ragweed, but will provide partial control of group 2-resistant common
ragweed. The higher rates will provide the most effective control of group 2-resistant pigweed, waterhemp, and
common ragweed.
в– в– Site of action: group 2 (chlorimuron, thifensulfuron); group 14 (flumioxazin). See pages 14-15.
в– в– Canan be applied anytime in fall or spring, but must be applied before soybean emergence and no later than 3
days after planting. Do not apply to frozen or snow-covered ground.
в– в– Preplant applications of Envive/Enlite can control small, emerged annual weeds up to 3 inches tall, including prickly
lettuce, wild garlic, common ragweed, and mustard species. Control of common chickweed requires the addition of
Express or glyphosate. Spring treatments should include 2,4-D ester and/or glyphosate for most effective control
of emerged weeds. Glyphosate should be included in applications later than early April and where dandelion and
other perennials are present. Mixtures with glyphosate or glyphosate plus 2,4-D have been among the most effective spring treatments for dandelion control in OSU and Purdue University research.
Soybeans
Herbicide
Formulation
Product Rate Range
Command
3ME
1 1/3 - 2 2/3 pt
в– в– Command (clomazone) controls annual grasses, velvetleaf, lambsquarters, and smartweed, and controls or suppresses jimsonweed and common ragweed. The lower rates control velvetleaf and suppress grasses and some
broadleaf weeds.
в– в– Site of action: group 13 (see pages 14-15).
в– в– Many ornamental, vegetable, and agronomic crops are sensitive to Command spray drift and vapors moving
outside the target area. Chlorosis or bleaching of sensitive plants may occur. Do not apply within 1200 feet of the
following areas: towns and housing developments, commercial fruit or vegetable production, commercial greenhouses or nurseries. Do not apply within 300 feet of other desirable plants. Do not apply in winds above 10 mph,
do not exceed a spray pressure of 30 psi, and do not rinse spray equipment near desirable plants. Do not apply to
fence rows, waterways, ditches and roadsides.
100
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
в– в– Apply with COC or modified seed oil (1% v/v) or NIS (0.25% v/v) for control of emerged weeds.
в– в– Soybean stunting may occur when rainfall results in prolonged wet soil conditions following application. Excessive rainfall shortly after soybean emergence can result in minor leaf necrosis or crinkling, or loss of lower leaves.
Risk of injury can be minimized by not using this product on poorly-drained soils, planting seeds at least 1.5 inches
deep, ensuring that seeds are completely covered with soil, and applying a week or more prior to planting.
в– в– Envive and Enlite can be mixed with pyroxasulfone with no added restrictions. Do not mix with products containing
alachlor, metolachlor, s-metolachlor, flufenacet, or dimethenamid when applied within 14 days of planting, unless
soybeans are planted under no-tillage or minimum tillage conditions in wheat stubble or no-till field corn stubble.
Soybeans
Herbicide
Formulation
Product Rate Range
Fierce
76WDG
3 - 3.75 oz
в– в– Fierce is a premix of flumioxazin (Valor) and pyroxasulfone (Zidua) that controls or suppresses annual grass and
broadleaf weeds. See Valor and Zidua descriptions for more information.
в– в– The application rates are intended to provide early-season control only. Preplant application of Fierce should be
followed with a broad-spectrum postemergence herbicide treatment.
в– в– Site of action: group 14 (flomioxazin), group 15 (pyroxasulfone). See pages 14-15.
в– в– Apply no later than 3 days after soybean planting, and prior to soybean emergence. Do not incorporate into the
soil following application.
в– в– Do not apply in a mixture with any of the following herbicides unless following directions on a Valent supplemental
label: flufenacet, metolachlor or s-metolachlor, alachlor, dimethenamid-p, or acetochlor.
Herbicide
Formulation
Product Rate Range
Fierce XLT
62.4WDG
3.75 - 5.25 oz
в– в– Fierce XLT is a premix of chlorimuron, flumioxazin (Valor) and pyroxasulfone (Zidua) that controls or suppresses annual grass and broadleaf weeds. Do not use a rate higher than 3.75 oz/A where composite soil pH is 6.8 or greater.
See Valor XLT, and Zidua descriptions for more information.
в– в– Site of action: group 14 (flomioxazin), group 15 (pyroxasulfone); group 2 (chlorimuron). See pages 14-15.
в– в– Apply no later than 3 days after soybean planting, and prior to soybean emergence. Do not incorporate into the
soil following application. Risk of injury can be minimized by not using this product on poorly-drained soils, planting
seeds at least 1.5 inches deep, ensuring that seeds are completely covered with soil, and applying a week or more
prior to planting.
в– в– Do not apply with products containing any of the following herbicides: flufenacet, metolachlor or s-metolachlor,
alachlor, dimethenamid-p, or acetochlor.
Fierce XLT Use Rates (oz/A)
Soil Texture
0.5-3% OM
3-5% OM
Coarse
3.75
3.75 - 4.5
Medium
3.75 - 4.5
3.75 - 5.25
Fine
4.5 - 5.25
4.5 - 5.25
Herbicide
Formulation
FirstRate84DF
в– в– FirstRate (cloransulam-methyl) controls many annual broadleaf weeds, including ragweeds, velvetleaf, lambsquarters,
pigweed, and cocklebur. Control of waterhemp is usually inadequate. Does not control group 2-resistant weeds.
в– в– Control of giant ragweed, morningglory, and cocklebur varies with rainfall, population, and application method.
Moderate to high population densities of giant ragweed will require an additional application of a postemergence
herbicide.
101
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
в– в– Site of action: group 2 (see pages 14-15).
в– в– Application rates in Ohio and north of I-64 in Indiana: and Illinois 3% or less soil organic matter - 0.6 oz; greater
than 3% organic matter - 0.75 oz. The rate is 0.75 oz south of I-64 in Indiana and Illinois.
в– в– For best results, apply within 2 weeks before planting. Do not apply earlier than 4 weeks before planting.
в– в– Preplant applications with COC plus UAN or AMS can control small emerged annual broadleaf weeds, including
ragweeds and annual smartweeds. Mixing with 2,4-D ester or other burndown herbicides will improve control of
most annual weeds.
Herbicide
Formulation
Product Rate Range
Gangster/Surveil
Co-pack
1.8 - 3.6 oz
в– в– Gangster/Surveil is a co-pack of flumioxazin (Valor) plus cloransulam (FirstRate) for annual broadleaf weed control
and limited grass suppression in soybeans. Does not control group 2-resistant giant ragweed, and provides partial
control of group 2-resistant common ragweed. See Valor and FirstRate descriptions for guidelines and precautions
on use.
в– в– Site of action: group 14 (flumioxazin), group 2 (cloransulam). See pages 14-15.
в– в– Lower labeled rates (1.8 to 2.4 oz) can be used when followed with a postemergence glyphosate application in
Roundup Ready soybeans. Rates of 2.4 to 3 oz should be used in non-Roundup Ready soybeans.
в– в– Apply no later than 3 days after soybean planting. To minimize risk of crop injury, apply a week or more prior to
planting.
в– в– Do not mix with products containing alachlor, metolachlor, s-metolachlor, flufenacet, or dimethenamid when applied
within 14 days of planting, unless soybeans are planted under no-tillage or minimum tillage conditions in wheat
stubble or no-till field corn stubble.
Herbicide
Formulation
Intimidator4.81L
в– в– Intimidator is a premix of fomesafen (Reflex), metribuzin, and s-metolachlor for preplant and preemergence control
of annual grass and broadleaf weeds. Controls many broadleaf weeds but is weak on giant ragweed, morninglory,
and cocklebur. For residual control of marestail, add enough metribuzin to attain the equivalent of 8 oz of metribuzin 75DF.
Soybeans
Herbicide
Formulation
Flumioxazin (active ingredient)
Valor/Encompass/Outflank/Panther51WDG
в– в– Flumioxazin can be applied preplant or preemergence for control of lambsquarters (including triazine-resistant),
black nightshade, pigweeds, waterhemp, and marestail (emerging from seed). Suppresses or provides partial control of common ragweed, morningglory, velvetleaf, smartweed, and some annual grasses.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Use rates: all coarse or medium-textured soils, and fine-textured soils with less than 3% OM - 2 to 2.5 oz; fine-textured soils with greater than 3% OM - 2 to 3 oz.
в– в– Apply no later than 3 days after soybean planting. Do not incorporate into the soil following application. To minimize risk of crop injury, apply a week or more prior to planting.
в– в– In university research, flumioxazin has occasionally stunted and slowed the growth of soybeans when high rainfall
conditions occur following soybean planting. The label states that risk of crop injury can be minimized by avoiding
use on poorly drained soils, planting at least 1ВЅ inches deep, and completely covering seeds with soil.
в– в– Do not mix with products containing alachlor, metolachlor, s-metolachlor, flufenacet, or dimethenamid when applied
within 14 days of planting, unless soybeans are planted under no-tillage or minimum tillage conditions in wheat
stubble or no-till field corn stubble.
102
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Soybeans
в– в– Site of action: group 15 - s-metolachlor; group 5 - metribuzin; group 14 - fomesafen. See pages 14-15.
в– в– Intimidator use rates for reduced or no-tillage soybeans: coarse-textured soils - 1.9 to 3.2 pts; medium-textured
soils - 3.2 to 4.48 pts; fine-textured soils - 4.48 pts. With a rate range, use the lower rates where soil OM is less than
3%, and the higher rares where soil OM is greater than 3%.
в– в– The total amount of fomesafen that should be used within the same season should not exceed 0.375 lb ai/A in
southern OH and IN, or 0.313 lb ai/A in northern OH or IN. Other products containing fomesafen: Flexstar, Flexstar
GT, and Prefix.
в– в– Injury to soybeans may occur where soil pH is 7.5 or greater, when heay rains occur soon after application, or when
soybeans are planted less than 1.5 inches deep.
Herbicide
Formulation
Latir
55 WDG
в– в– Latir is a premix of imazethapyr (Pursuit) and flumioxazin (Valor etc) for preplant and preemergence control of annual broadleaf weeds, and early-season suppression of annual grasses. Has no activity on group 2-resistant giant
ragweed, but provides control/suppression of group 2-resistant common ragweed.
в– в– Site of action: group 2 - imazethapyr; group 14 - flumioxazin. See pages 14-15.
в– в– Apply within 3 days after planting, and prior to cracking or soybean emergence.
в– в– Latir use rates: all soils with 0.5 to 2.5% organic matter - 3.2 to 3.8 oz; coarse- or medium-textured soils with 2.5
to 5% organic matter - 4.25 oz. When applied more than 30 days before planting, use higher labeled rates for soil
type.
в– в– Crop injury can occur when applied to poorly drained soils under cool, wet conditions. Excessive rainfall shortly
after soybean emergence can result in minor leaf necrosis or crinkling, or loss of lower leaves. Risk of injury can be
minimized by not using this product on poorly-drained soils, planting seeds at least 1.5 inches deep, ensuring that
seeds are completely covered with soil, and applying a week or more prior to planting.
в– в– Do not mix with products containing any of the following: flufenacet, metolachlor, dimethenemid-P, acetochlor, or
alachlor. Do not apply to frozen or snow-covered ground.
Herbicide
Formulation
Product Rate Range
Lorox
50DF
2/3 - 1 2/3 lb
4L
2/3 -1 2/3 pt
в– в– Lorox (linuron) controls many annual broadleaf weeds, including Pennsylvania smartweed, pigweeds, lambsquarters, and common ragweed. Helps suppress black nightshade and cocklebur, but does not control giant ragweed
or annual morningglory.
в– в– Site of action: group 7 (see pages 14-15).
в– в– Best-suited for use on medium-textured soils with 1 percent to 3 percent organic matter. Do not use on very sandy
soils.
в– в– Can provide burndown of small, emerged annual weeds present at application when mixed with 2,4-D ester.
в– в– Apply to the soil surface only. Do not incorporate following application. May occasionally injure soybeans. Accurate application of the correct rate based on soil type is important to reduce the risk of injury.
Herbicide
Formulation
Matador4.7L
в– в– Matador is a premix of imazethapyr (Pursuit), metribuzin, and metolachlor for preplant and preemergence control
of annual grass and broadleaf weeds. Controls many broadleaf weeds but is weak on giant ragweed, morninglory,
common ragweed, and cocklebur. For residual control of marestail, add enough metribuzin to attain the equivalent
of 8 oz of metribuzin 75DF.
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Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
в– в– Site of action: group 2 - imazethapyr; group 5 - metribuzin; group 15 - metolachlor. See pages 14-15.
в– в– Matador use rates for reduced or no-tillage soybeans: coarse-textured soils - 1.6 to 2.7 pts; medium-textured soils 2.7 to 4 pts; fine-textured soils - 4 pts. With a rate range, use the lower rates where soil OM is less than 3%, and the
higher rares where soil OM is greater than 3%.
в– в– Injury to soybeans may occur where soil pH is 7.5 or greater, when heay rains occur soon after application, or when
soybeans are planted less than 1.5 inches deep.
Herbicide
Formulation
s-Metolachlor7.64E
Metolachlor7.8E
в– в– S-metolachlor (Dual II Magnum/Cinch) and metolachlor (Parallel/Stalwart) control annual grasses and pigweed, and
control or suppress yellow nutsedge and black nightshade.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Incorporation to a depth of 2 inches will improve yellow nutsedge control and reduce dependence upon rainfall.
Dual II Magnum, Parallel, and Stalwart Use Rates (pts/A)
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
1 to 1.33
1.33
Medium
1.33 to 1.67
1.33 to 1.67
Fine
1.33 to 1.67
1.67 to 2
Herbicide
Formulation
Metribuzin4F
75DF
в– в– Metribuzin (Dimetric, Tricor, Glory) controls annual broadleaf weeds, including Pennsylvania smartweed, pigweeds,
waterhemp, lambsquarters, and marestail (emerging from seed). Control of common ragweed and velvetleaf is variable. Metribuzin does not adequately control annual morningglory, giant ragweed, cocklebur, or black nightshade.
в– в– Site of action: group 5 (see pages 14-15).
в– в– Preplant applications of metribuzin, paraquat, and 2,4-D ester can provide effective burndown in many no-till situations.
в– в– May injure soybeans when applied at high rates. Injury may be greater where soil pH is over 7.5, and where seedling diseases, weather stress, or atrazine carryover occur. Soybean varieties vary in tolerance to metribuzin. Selection of a variety with above-normal tolerance to metribuzin will reduce the risk of crop injury.
в– в– To avoid soybean injury, accurately apply the correct rate based on soil type. Do not use on sandy soil that is low in
organic matter.
в– в– Can be applied in the fall with 2,4-D ester for control of winter annual weeds, including marestail, mustards, purple
deadnettle, and common chickweed.
Soybeans
в– в– Use rates for most products are similar: coarse-textured soils - 1 to 1.33 pt/A; all medium-textured soils, and finetextured soils with less than 3% OM - 1.33 to 1.67 pt/A; fine-textured soils, less than 3% - 1.67 to 2 pt/A.
в– в– May be applied up to 30 days before planting as a single application.
в– в– Can be applied postemergence (up to 90 days before harvest), for residual control of weeds only. Mix with herbicides with postemergence activity to control emerged weeds.
104
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Metribuzin 75 DF Use Rates (lb/A)
Soybeans
Soil Texture Group
Soil Organic Matter Content
Less than 2%
2% to 4%
More than 4%
Coarse
Do not use
0.5
0.75
Medium
0.5 to 0.75
0.75 to 0.83
0.83 to 1
Fine
0.75 to 0.83
0.83 to 1
1 to 1.17
Herbicide
Formulation
Product Rate Range
Optill PRO
co-pack
в– в– Optill PRO is a co-pack of Outlook (dimethenamid-P) with a dispersible dry premix of saflufenacil (Sharpen) and
imazethapyr (Pursuit). Outlook PRO provides residual control of grass and broadleaf weeds, and can help burndown emerged weeds in no-till, especially marestail. It should generally be combined with glyphosate or Liberty for
burndown.
в– в– Site of action: group 14 (saflufenacil); group 2 (imazethapyr); group 15 (dimethenamid-P). See pages 14-15.
в– в– Apply prior to crop cracking or emergence. On coarse-textured soils with 2% organic matter or less, apply at least
30 days before planting.
в– в– Salfufenacil products used in soybeans cannot be mixed with or applied within 30 days of products containing
flumioxazin (Valor products, Envive, and Gangster), sulfentrazone (Authority products), or fomesafen (Prefix, Intimidator).
в– в– Burndown activity requires the addition of MSO (1% v/v) plus either AMS (8.5 to 17 lbs/100 gallons) or UAN (1.25 to
2.5% v/v).
в– в– Ensure that the seed furrow is closed and seed row sufficiently covered with soil to avoid washing and concentration of saflufenacil in the seed zone.
Herbicide
Formulation
Outlook6EC
в– в– Outlook (dimethenamid-P) controls annual grasses and pigweed, and control or suppress yellow nutsedge and
black nightshade.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Application rates vary with soil texture, organic matter content, and CEC. Can be applied early postemergence on
soybeans up to the 5th trifoliate stage, but will not control emerged grasses.
в– в– Can be incorporated into the upper 1 to 2 inches of soil up to 2 weeks before planting. Incorporation will improve
yellow nutsedge control.
в– в– Can be applied up to 30 days before planting as a single application.
Outlook Use Rates (floz/A)a
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
12 to 14
14 to 18
Medium and Fine
14 to 18
18 to 21
a. Not recommended on soils with CEC values less than 5 or coarse soils with less than 1.5% organic matter.
105
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Pendimethalin/Pendimax/Pendant/etc3.3EC
Prowl H2O/Satellite Hydrocap
3.8CS
в– в– The active ingredient in these products, pendimethalin, controls annual grasses, pigweed, and lambsquarters and
helps control smartweed and velvetleaf.
в– в– Site of action: group 3 (see pages 14-15).
в– в– Preplant applications should be incorporated within 7 days after application. Incorporation may not be necessary if
sufficient rainfall occurs.
в– в– When applied without incorporation, apply from 15 days before planting through 2 days after planting.
в– в– Application close to or after planting may result in soybean injury, including stem swelling and brittleness. To reduce
the risk of injury, apply early preplant or incorporate prior to planting.
Prowl H2O/Satellite Hydrocap Use Rates (pt/A)
Soil Texture
Pendimethalin 3.3EC Use Rates (pt/A)
Soil Texture
Coarse
Medium
Fine
Soil Organic Matter Content
Less than 3%
More than 3%
1.8
1.8 to 2.4
2.4 to 3
2.4 to 3.6
2.4 to 3.6
3 to 3.6
The high rates for each soil texture above should be used if heavy weed populations are anticipated, extensive crop residues were present prior to seedbed preparation, or in no-till.
Herbicide
Formulation
Product Rate Range
Pummel
5.25L
4 oz
в– в– Pummel is a premix of imazethapyr (Pursuit) and metolachlor that controls annual grass and broadleaf weeds. Pursuit is weak on common ragweed, and less effective than several other group 2 herbicides on giant ragweed. This
product will be variable for residual control of marestail and will not control group 2-resistant populations of marestail or ragweeds. See Pursuit and metolachlor descriptions for more information.
в– в– Site of action: group 2 (imazethapyr); group 15 (metolachlor). See pages 14-15.
в– в– Can be applied preplant (up to 30 days before planting), preemergence, or postemergence prior to the V3 soybean
stage. NIS (0.25% v/v) plus UAN (1-2 qt/A) or AMS (4 lbs/A) should be included in postemergence applications for
control of emerged weeds.
в– в– Application rates: 2 pts - medium and fine-textured soils; 1.6 pts - coarse-textured soils with at least 3% organic matter. DO not use on coarse-textured soils with less than 3% organic matter.
Soybeans
Coarse
Medium
Fine
Soil Organic Matter Content a
Less than 3%
More than 3%
1.5
1.5 to 2
2 to 2.5
2 to 3
2 to 3
2.5 to 3
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Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
Pursuit
2S
4 oz
в– в– Pursuit (imazethapyr) controls annual broadleaf weeds and controls or suppresses annual grasses. Pursuit is weak
on common and giant ragweed. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Pursuit may be applied preplant (up to 45 days before planting), preplant incorporated, preemergence, or postemergence. Postemergence applications provide more consistent control than soil-applied treatments.
Soybeans
Herbicide
Formulation
Product Rate Range
Python
80WDG
0.8-1.33 oz.
в– в– Python (flumetsulam) controls annual broadleaf weeds, including velvetleaf, lambsquarters (including triazine-resistant), and pigweeds. Control of common ragweed is variable. Python does not adequately control cocklebur, giant
ragweed, or annual morningglory. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Python use rates range from 0.8 to 1 oz/A on coarse-textured soils, and 0.9 to 1.33 oz/A in medium or fine-textured
soils.
в– в– May by applied up to 30 days before planting. Rates increase when applied early, compared to application at planting. Preplant application of Python will control small mustards and field pennycress when applied with COC and
2,4-D.
в– в– Do not apply to soils with the combination of pH less than 5.9 and organic matter content greater than 5%. Do not
apply where soil pH is greater than 7.8.
Herbicide
Formulation
Product Rate Range
Scepter
70DG
2.8 oz
в– в– Scepter (imazaquin) controls many annual broadleaf weeds, including lambsquarters, Pennsylvania smartweed,
pigweeds, black nightshade, ragweeds, and cocklebur. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Residual control of large-seeded broadleaf weeds (cocklebur, giant and common ragweed) varies with rainfall,
population, and application method; early preplant application will provide most effective control of these weeds.
в– в– Imazaquin may persist for long periods in soil, especially where excessive rates occur from misapplication or
streaked incorporation. Accurate application and uniform incorporation are important for follow-crop safety. Carryover is more likely in soils high in organic matter and clay, especially where soil pH is less than 6, and when
droughty conditions occur during the season of application.
в– в– Corn may be planted 9 1/2 months after application if at least 15 inches of rain is received between 2 weeks before application and November 15 of the same year. If this condition is not met, plant only imidazolinone-tolerant
(Clearfield) corn the next year.
Herbicide
Formulation
Sequence5.25L
в– в– Sequence is a premix of glyphosate plus s-metolachlor (Dual II Magnum) for preplant or preemergence application.
See glyphosate and s-metolachlor descriptions for more information.
в– в– Can be applied at reduced rates when followed by a postmergence herbicide treatment.
в– в– Can be applied postemergence to Roundup Ready soybeans to provide control of emerged weeds and residual
control of annual grasses, black nightshade, pigweeds, and waterhemp. Apply between cracking and the 3rd trifoliate soybean stage.
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Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Sequence Use Rates (pt/A)
Soil Texture Group
Less than 3% OM
3% or Greater OM
Coarse
2.5 to 3.5
3.5
Medium
3.5 to 4
3.5 to 4
Fine
3.5 to 4
4
Minimum preplant interval (days) required between Sharpen application and
soybean planting numbers in ( ) are for tank-mix with group 14 herbicides
Use rate -oz
Soil texture
Coarse soils with 2% or less OM
All other soils
1.0
30 (30)
0 (14)
1.5
30 (30)
14 (30)
2.0
44 (44)
30 (30)
Minimum preplant interval (days) required between Verdict application and
soybean planting
Use rate (oz)
Soil texture
Coarse soils with 2% or less OM
All other soils
5.0
30
0
7.5
30
14
10
44
30
Soybeans
Herbicide
Formulation
Product Rate Range
Sharpen
2.85SC
1 to 2 oz
Verdict
5.57EC
5 to 10 oz
в– в– Sharpen (saflufenacil) can help burndown emerged weeds in no-till, especially marestail. It provides a low level (40
to 60%)of residual control of broadleaf weeds at the 1 oz rate, and residual control improves with increasing rate.
The 1.5 and 2 oz rates have provided substantial residual control of marestail in OSU research, especially when
mixed with other residual herbicides. It should be combined with glyphosate or Liberty for burndown, and with
other residual herbicide(s) for broad-spectrum residual control.
в– в– Verdict is a premix of salflufenacil and dimethenamid-p (Outlook), which improves residual control of grasses and
a few small-seeded broadleaf weeds, compared with Sharpen. The 5 oz rate of Verdict provides the equivalent
amount of saflufenacil in 1 oz/A of Sharpen.
в– в– Site of action: Sharpen - group 14; Verdict - group 14 (saflufenacil) and group 15 (dimethenamid-p). See pages 14-15.
в– в– Apply prior to crop emergence. Rates vary based on soil texture and timing of application - see rate tables.
в– в– Salfufenacil products used in soybeans cannot be mixed with or applied within 30 days of group 14 products containing flumioxazin (Valor products, Envive, Gangster, etc), sulfentrazone (Sonic, Authority products), or fomesafen
(Prefix, Intimidator, etc), with the following exception: Sharpen can be applied 14 days before planting when mixed
with these herbicides except on coarse-textured soils with less than 2% organic matter..
в– в– Burndown activity requires the addition of MSO (1% v/v) plus either AMS (8.5 to 17 lbs/100 gallons) or UAN (1.25 to
2.5% v/v).
в– в– Ensure that the seed furrow is closed and seed row sufficiently covered with soil to avoid washing and concentration of saflufenacil in the seed zone.
108
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Soybeans
Herbicide
Formulation
Product Rate Range
Sonic/Authority First
70 WDG
3 - 8 oz
в– в– Sonic/Authority First is a premix of sulfentrazone (Spartan) and cloransulam (FirstRate) that controls many broadleaf
weeds.
в– в– Site of action: group 14 (sulfentrazone); group 2 (cloransulam). See pages 14-15.
в– в– Can be applied at rates as low as 3 oz/A in Roundup Ready soybeans, when followed with a postemergence
glyphosate application. Use rates in non-Roundup Ready soybeans: 3% or less OM - 6.5 oz; greater than 3% OM 8 oz.
в– в– Apply preplant or preemergence, up to 3 days after soybean planting. To minimize risk of crop injury, apply a week
or more prior to planting.
в– в– In preplant burndown applications, apply with NIS (1 to 2 pts/100 gallon) or COC (1.2 gallon/100 gallons), plus AMS
(17 lb/100 gallon). Mix with glyphosate and 2,4-D for most effective control of emerged weeds in no-till.
Herbicide
Formulation
Spartan4F
Spartan Advance
4.6L
в– в– Spartan (sulfentrazone) controls black nightshade, marestail (emerging from seed), pigweeds, lambsquarters, kochia, and waterhemp, and can suppress annual grasses and annual morningglory. Spartan Advance is a premix of
sulfentrazone and glyphosate.
в– в– Site of action: group 14 (see pages 14-15).
в– в– May cause stunting of soybeans if excessive rain occurs between application and soybeans emergence. Soybeans
generally outgrow this injury, but some soybean varieties are more sensitive to this herbicide and can be severely
injured. Check with seed supplier for varietal tolerance information prior to use.
Spartan use rates (oz/A)
% organic matter
Soil texture
Coarse
Medium
Fine
< 1.0%
4.5 to 6
6 to 8
8
1 to 3%
6 to 8
8 to 10.1
10.1
> 3%
8 to 10.1
10.1 to 12
12
Herbicide
Formulation
Treflan/Trifluralin
4EC, HFP, HF
10G
в– в– Treflan (trifluralin) controls annual grasses, pigweed, waterhemp, and lambsquarters and helps control smartweed,
morningglory, and johnsongrass.
в– в– Site of action: group 3 (see pages 14-15).
в– в– Treflan HFP rates: coarse-textured soils, less than 2% OM - 1 pt/A; coarse-textured soils with 2 to 5% OM and
medium-textured soils - 1.5 pts/A; fine-textured soils - 2 pts/A.
в– в– Must be incorporated into the soil (depth of 2 to 3 inches) within 24 hours after application. For best results, make
two incorporation passes in different directions.
109
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Herbicide
Formulation
Product Rate Range
Valor XLT
40 WDG
2.5 to 5 oz
в– в– Valor XLT is premix of chlorimuron (Classic) plus flumioxazin (Valor) for residual control of most annual broadleaf
weeds. Control of cocklebur, morningglory, and giant ragweed varies with rainfall and population. Early preplant
application will provide most effective control of giant ragweed.
в– в– Valor XLT will not control group 2-resistant giant ragweed, but will provide partial control of group 2-resistant common ragweed. The 5 oz rate will provide the most effective control of group 2-resistant pigweed, waterhemp, and
common ragweed.
в– в– Site of action: group 2 (chlorimuron); group 14 (flumioxazin). See pages 14-15.
в– в– Valor XLT can be applied in fall or spring, but must be applied before soybean emergence and no later than 3 days
after planting. Do not apply to frozen or snow-covered ground. Fall applications should be made after October 15,
or when soil temperature is below 50 F.
в– в– Apply 3 to 4 oz to soils with 0.5 to 3% OM, and 3 to 5 oz to soils with 3 to 5% OM. Rates of 3 to 3.5 oz/A can be
used when followed by postemergence application of glyphosate in Roundup Ready soybeans. Maximum rate on
soils where the composite pH exceeds 6.8 is 2.5 oz.
в– в– Preplant application of Valor XLT can control small, emerged annual weeds up to 3 inches tall, including prickly lettuce, wild garlic, common ragweed, and mustard species. Control of common chickweed requires the addition of
Express or glyphosate. Fall applications of Valor XLT should include 2,4-D and Express. Spring burndown applications should include glyphosate or glyphosate plus 2,4-D ester. Mixtures of Valor XLT with glyphosate or glyphosate plus 2,4-D have been among the most effective spring treatments for dandelion control in OSU and Purdue
University research.
в– в– Soybean stunting may occur when rainfall results in prolonged wet soil conditions following application. Risk of
injury can be minimized by not using this product on poorly-drained soils, planting seeds at least 1.5 inches deep,
ensuring that seeds are completely covered with soil, and applying a week or more prior to planting.
в– в– Do not mix with products containing alachlor, metolachlor, s-metolachlor, flufenacet, or dimethenamid when applied
within 14 days of planting, unless soybeans are planted under no-tillage or minimum tillage conditions in wheat
stubble or no-till field corn stubble.
Soybeans
Herbicide
Formulation
Product Rate Range
Trivence
61.3 WDG
6 - 10 oz
в– в– Trivence is premix of chlorimuron (Classic), flumioxazin (Valor), and metribuzin for residual control of most annual
broadleaf weeds, including group 2-resistant marestail, waterhemp, and Palmer amaranth. Control of cocklebur,
morningglory, and giant ragweed varies with rainfall and population. Early preplant application will provide most effective control of giant ragweed. See descriptions of Envive and metribuzin for more information.
в– в– Trivence will not control group 2-resistant giant ragweed, but will provide partial control of group 2-resistant common ragweed.
в– в– Site of action: group 2 (chlorimuron); group 14 (flumioxazin); group 5 (metribuzin). See pages 14-15.
в– в– Trivence can be applied anytime in fall or spring, but must be applied before soybean emergence and no later than
3 days after planting. Do not apply to frozen or snow-covered ground.
в– в– Maximum rate on soils where the composite pH exceeds 7.0 is 6 oz.
в– в– Soybean stunting may occur when rainfall results in prolonged wet soil conditions following application. Excessive
rainfall shortly after soybean emergence can result in minor leaf necrosis or crinkling, or loss of lower leaves. Risk of
injury can be minimized by not using this product on poorly-drained soils, planting seeds at least 1.5 inches deep,
ensuring that seeds are completely covered with soil, and applying a week or more prior to planting.
в– в– Trivenece can be mixed with pyroxasulfone with no added restrictions. Mixtures of Trivence with products containing s-metolachlor, metolachlor, alachlor, dimethenamid, or flufenacet should be applied at least 14 days prior to
planting to avoid crop injury.
110
Soybeans: Soil-Applied Herbicides — Preplant or Preemergence
Soybeans
Herbicide
Formulation
Warrant3L
в– в– Warrant (acetochlor) can be applied preplant, preemergence, or early postemergence to soybeans for residual
control of annual grasses, lambsquarters, pigweed, waterhemp, and black nightshade. Warrant applied alone does
not control emerged weeds, but a postemergence mixture of glyphosate and Warrant will control emerged weeds
and provide residual control.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Rates for preplant/preemergence application on soils with more than 1.5% OM, based on soil texture: coarse - 1.25
to 1.7 qts; medium - 1.25 to 1.9 qts; fine - 1.25 to 2.0 qts.
в– в– Postemergence applications should be prior to the R2 stage, and prior to weed emergence or in combination with
glyphosate to control emerged weeds.
в– в– Optimum timing and rate of application (when applied postemergence with glyphosate) is 1.5 qts/A when weeds
are 2 to 4 inches tall, and soybeans are at V2 to V3. Labeled rates range from 1.25 to 2 qts/A depending upon soil
texture and organic matter content.
Herbicide
Formulation
Zidua85WDG
в– в– Zidua (pyroxasulfone) can be applied preplant, preemergence, or early postemergence in soybeans for residual
control of annual grasses and small-seeded broadleaf weeds. This product should generally be combined with
other preemergence corn herbicide(s) to improve broadleaf weed control, or followed with a postemergence herbicide treatment.
в– в– Site of action: group 15 (see pages 14-15).
в– в– Application rates based on soil texture: Preemergence - coarse - 1.5 to 2.1 oz; medium - 2 to 3 oz; fine - 2.5 to 3.5
oz; postemergence - coarse - 1.0 to 2.1 oz; medium - 1.5 to 3 oz; fine - 2.0 to 3.5 oz.
в– в– Check with seed supplier for information on soybean variety tolerance to Zidua.
в– в– Early postemergence applications will not control emerged weeds. Apply when soybeans are in the first to third trifoliate stage. May couse temporary leaf burn and stunting to soyeans when applied postemergence. Do not apply
from the cracking through unifoliate stage of soybean growth.
111
Soybeans: Postemergence/Residual Premixes
Herbicide
Formulation
Anthem2.15SE
в– в– Anthem is a premix of pyroxasulfone (Zidua) and fluthiacet (Cadet) that can be applied preplant, preemergence, or
early postemergence in soybeans for residual control of annual grasses and small-seeded broadleaf weeds. Residual control is provided solely by the pyroxasulfone.
в– в– Site of action: group 15 (pyroxasulfone); group 14 - fluthiacet. See pages 14-15.
в– в– When applied early postemergence, the fluthiacet component can control or help control some broadleaf weeds,
but should be mixed with other postemergence herbicides. Apply when soybeans are up to the third trifoliate stage
(V3). May couse temporary leaf burn and stunting to soyeans when applied postemergence.
в– в– Include NIS (0.25% v/v) or COC/MSO (1 to 2 pts/A) with postemergence applications. Follow adjuvant recommendations for partner herbicides in tank mixes. Additional adjuvants are not needed when mixing with Liberty/Cheetah
or glyphosate products that already contain surfactant.
Anthem PRE/POST use rates (oz/A)
% organic matter
Soil texture
Medium
Fine
PRE < 3%
5 to 6.5
6.5 to 9.5
8.5 to 11
PRE > 3%
6.5
8 to 9.5
10 to 11
POST - any
4 to 6.5
5 to 9
6.5 to 11
Herbicide
Formulation
Product Rate Range
Prefix
5.29L
2 - 3 pts
Vise
5.4L
2 - 3 pts
Statement
5.24L
2 - 3 pts
в– в– These products are premixes of s-metolachlor or metolachlor (Dual II Magnum, etc) plus fomesafen (Reflex) that can
be applied preplant, preemergence or early postemergence. Preplant/preemergence applications provide earlyseason control of annual grasses and small-seeded broadleaf weeds, including black nightshade, pigweeds, common ragweed, and waterhemp, and should be followed by a postemergence herbicide program. See metolachlor
and Reflex descriptions for more information.
в– в– Prefix and Vise can be applied early postemergence (Prefix - up to 90 days before harvest; Vise - through the 3rd
trifoliate stage) at rates of 2 - 2.33 pts/A to control emerged weeds and provide residual control of grasses and
some broadleaf weeds, including waterhemp and Palmer amaranth. Should generally be mixed with glyphosate
to broaden the spectrum of control. Include NIS (0.25% v/v) in postemergence applications unless mixing with a
glyphosate product that contains surfactant. Do not apply with COC or MSO. Statement did not have a POST label
yet at time of publication.
в– в– Site of action: group 15 (s-metolachlor), group 14 (fomesafen). See pages 14-15.
в– в– Maximum preplant/preemergence use rates: north of I-70 - 2.5 pts; south of I-70 - 3 pts. See labels for more information on rates north and south of I-70.
в– в– Do not apply postemergence to fields that have received a preplant/preemergence treatement of s-metolachlor.
Herbicide
Formulation
Product Rate Range
Torment
2.5L
3/4 - 1 pt
в– в– Torment is a premix of imazethapyr (Pursuit) and fomesafen (Reflex) that can be applied preplant, preemergence,
or early postemergence for residual control and control of emerged weeds. This product will be less effective for
residual control of waterhemp and Palmer amaranth compared with Prefix/Vise. See Pursuit and Reflex descriptions
for more information.
в– в– Site of action: group 2 (imazethapyr); group 14 (fomesafen). See pages 14-15.
Soybeans
Coarse
112
Soybeans: Postemergence/Residual Premixes
Soybeans
в– в– Postemergence applications should occur when weeds are less than 3 inches tall, approximately 14 to 28 days after
planting in the absence of a prior residual herbicide treatment. Include COC or MSO (0.5 to 1% v/v) or NIS (0.25 to
0.5% v/v) in postemergence applications, plus either UAN (1 to 2.5% v/v) or AMS (at least 8.5 lbs/100 gal).
в– в– Apply in a spray volume of at least 15 gpa with a pressure of 30 to 60 psi. When weed foliage is dense use a spray
volume of at least 20 gpa with a pressure of 60 psi.
113
Soybeans: Postemergence Herbicides — Contact
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Aim
2EC
0.25 oz
Not addressed on label
в– в– Aim (carfentrazone) is a contact herbicide that controls primarily velvetleaf at 0.25 oz rate.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply when soybeans are in the V3 to V10 stage. Do not use on soybeans with maturity less than 2.0. Maximum
broadcast rate: 0.25 oz/A for 2.1 to 3.4 maturity; 0.5 oz for maturity of 3.5 or higher.
в– в– Apply with NIS (0.25% v/v) in a spray volume of 10 to 20 gpa.
в– в– Always add Aim to the spray tank first when mixing with other herbicides.
в– в– Application of Aim is likely to cause soybean leaf burn.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Cadet
0.91EC
0.4 - 0.9 oz
0.4 - 0.6 oz
в– в– Cadet (fluthiacet-methyl) is a contact herbicide that controls velvetleaf, and controls or suppresses small lambsquarters, pigweeds, black nightshade, and annual morningglory at the 0.9 oz rate.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply from first trifoliate stage through flowering, but at least 60 days before harvest.
в– в– Apply with NIS (0.25% v/v), or a COC or MSO (1 to 2 pts/A). UAN (1 to 2 qts/A) or AMS can be added. When combined with other herbicides, Cadet can generally be applied with any adjuvants required for those herbicides.
в– в– Apply in a minimum spray volume of 15 gpa and pressure of 20-40 psi. Increase volume and pressure in dense
crop and weed canopies.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Soybeans
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Basagran/Broadloom
4L
1 - 2 pt 1 - 2 pt
в– в– Basagran/Broadloom (bentazon) is a contact herbicide that controls many annual broadleaf weeds, but is weak
on pigweed, ragweeds, and annual morningglories. At higher rates, controls or suppresses yellow nutsedge and
Canada thistle.
в– в– Site of action: group 6 (see pages 14-15).
в– в– Apply with COC (1.25% v/v) and/or nitrogen fertilizer (UAN or AMS). The label suggests the use of UAN (1/2 to 1
gallon/A) or AMS (2.5 pound/A) in place of COC where velvetleaf is the primary target weed. COC must also be
used if common ragweed and lambsquarters are present. Additive recommendations vary when mixing with other
herbicides; see the label for additional information.
в– в– Apply in a spray volume of at least 20 gpa with a minimum pressure of 40 psi. Increasing spray volume (up to 50
gpa) will improve control when crop and weed foliage is dense.
в– в– Application with Flexstar will improve control of morningglory, giant ragweed, and pigweed.
в– в– The addition of 2 fluid ounces of 2,4-DB will improve morningglory control. Do not add crop oil or UAN when applying with 2,4-DB.
в– в– May cause temporary soybean leaf burn, but is less injurious to soybeans than most other postemergence herbicides.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, or if mixing with Liberty, just add AMS.
114
Soybeans: Postemergence Herbicides — Contact
Herbicide
Formulation
Product Rate Range
With Glyphosate
Cobra/Phoenix
2L
8 - 12.5 oz
8 - 12.5 oz
в– в– Cobra/Phoenix (lactofen) is a contact herbicide that is similar to Flexstar in weeds controlled. In OSU research,
Flexstar has been more consistently effective than Cobra on giant and common ragweed and annual morningglory.
Cobra can suppress some perennial vines, including climbing milkweed and bigroot morningglory.
в– в– Site of action: group 14 (see pages 14-15).
в– в– For best results, apply with COC (0.25 to 1%, v/v) up to the 4- to 6-leaf stage of weeds. Surfactant, UAN, or AMS
may be substituted for COC when weeds are actively growing under high temperature, high humidity, and high soil
moisture conditions. Do not use surfactant when relative humidity is less than 80 percent.
в– в– Apply at least 45 days prior to harvest.
в– в– Apply in a spray volume of 20 to 30 gallons per acre at a spray pressure of 40 to 60 psi using flat fan or hollow
cone nozzles.
в– в– Cobra causes more severe soybean leaf burn than other postemergence herbicides. Phoenix causes less injury to
soybeans than Cobra.
Soybeans
в– в– When mixing with glyphosate, add AMS (2.5 to 4.5 lb/A).
Herbicide
Formulation
Product Rate Range
With Glyphosate
Flexstar/Rhythm
1.88L
1 - 1.6 pints
6 - 12 oz
в– в– Flexstar/Rhythm (fomesafen) controls annual broadleaf weeds, including ragweeds, cocklebur, pigweeds, waterhemp, annual morningglories, velvetleaf, Pennsylvania smartweed, and black nightshade. Can suppress Canada
thistle, bindweeds, and climbing milkweed, but does not control lambsquarters.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Maximum rates: north of I-70 - 1.3 pints; south of I-70 - 1.6 pints.
в– в– Apply in a spray volume of 15 to 20 gpa (use 20 gpa in dense foliage) with a spray pressure of 30 to 60 psi.
в– в– Apply with COC or MSO (0.5 to 1% v/v) or NIS (0.25 to 0.5%), plus UAN (minimum of 1% v/v) or AMS (minimum of 4
lbs/100 gallons). MSO is the preferred adjuvant for effectiveness on weeds, but can cause more soybean leaf burn
than COC.
в– в– Flexstar/Rhythm can reduce the activity of postemergence grass herbicides mixtures, especially under droughtstress conditions. To avoid a reduction in grass control, apply Flexstar/Rhythm 2 to 3 days after the postemergence
grass herbicide is applied, or wait about 7 days after Flexstar/Rhythm is applied before applying the grass herbicide.
See label for more information.
в– в– Often causes temporary soybean leaf burn.
в– в– Do not apply more than once every two years.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Marvel
3L
5 - 7.5 oz
5 - 7.5 oz
в– в– Marvel is a premix of fomesafen (Reflex) and fluthiacet methyl (Cadet) that controls small annual broadleaf weeds.
See Reflex and Cadet descriptions for more information.
в– в– Site of action: group 14 (see pages 14-15).
в– в– This product often causes temporary soybean leaf burn, which will be more severe when applied with COC.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system or mixing with Liberty, just add AMS.
в– в– Apply with NIS (0.25 to 0.5% v/v), or COC/MSO (0.5 percent to 1 percent v/v). UAN or AMS can be added to the
spray mixture along with one of these adjuvants. USe of COC or MSO is recommended under dry conditions or low
relative humidity.
115
Soybeans: Postemergence Herbicides — Contact
Herbicide
Formulation
Product Rate Range
With Glyphosate
Resource
0.86EC
4 - 12 oz 2 - 4 fl oz
в– в– Resource (flumiclorac) is a contact herbicide that controls velvetleaf and pigweeds. Control of lambsquarters is variable, and some other broadleaf weeds will be suppressed.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply 4 to 8 ounces/A when broadleaf weeds are in the 2- to 3-leaf stage for best results. The 8 ounce rate will
control velvetleaf up to 24 inches tall. Use 12 ounces /A for velvetleaf up to 30 inches tall.
в– в– Apply in a spray volume of at least 10 gpa with a spray pressure of 30 to 60 psi.
в– в– Resource applied alone and in mixtures with most other herbicides requires the use of COC (1 quart/A) . The addition of liquid nitrogen fertilizer may enhance control of tall velvetleaf and is required in some mixtures. See the
label for more information.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Rezult
Co-pack
3.25 pts
Not addressed on label
в– в– Rezult is a co-pack of Poast Plus (premix of sethoxydim plus Dash) plus Basagran (bentazon). The use rate contains
the equivalent of 1.6 pints of Poast Plus and 1.6 pints of Basagran. See Poast Plus and Basagran descriptions and
product labels for more information.
в– в– Site of action: group 6 (bentazon), group 1 (sethoxydim). See pages 14-15.
в– в– Apply when most weeds are 2 to 4 inches tall in a spray volume of 10 to 20 gpa with a spray pressure of at least 40
psi (60 psi where foliage is dense).
в– в– Include UAN (28, 30, or 32% - 2 quarts/A) in the spray mix when applied alone or in combination with Classic. Apply with a silicon adjuvant (1 to 2 pints/100 gallons spray) when applied with Blazer or Reflex.
Soybeans
Herbicide
Formulation
Product Rate Range
With Glyphosate
Reflex/Dawn
2LC
1 - 1ВЅ pt
6 - 12 oz
в– в– Reflex/Dawn (fomesafen) is similar to Flexstar in weed control spectrum but is less effective on cocklebur and velvetleaf.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Maximum rate: north of I-70 - 1Вј pints; south of I-70 - 1ВЅ pints.
в– в– Apply when weeds are less than 4 inches tall and actively growing. Do not apply to weeds growing under drought
stress or when maximum daytime temperatures are less than 70 degrees.
в– в– Apply with COC (0.5 percent to 1 percent v/v) or NIS (0.25 percent to 0.5 percent v/v). UAN can be added to the
spray mixture along with COC or NIS, which may improve control of velvetleaf and other weeds. Do not substitute
UAN for COC or NIS.
в– в– Apply in a spray volume of at least 10 gpa with a pressure of 40 to 60 psi. When weed foliage is dense use a spray
volume of at least 20 gpa with a pressure of 60 psi.
в– в– Application in combination with Basagran will improve control of velvetleaf, cocklebur, giant ragweed, and some
other weeds.
в– в– The addition of 2 to 3 fluid ounces of 2,4-DB will improve morningglory, giant ragweed, and cocklebur control.
в– в– Often causes temporary soybean leaf burn.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
116
Soybeans: Postemergence Herbicides — Contact
Soybeans
Herbicide
Formulation
Product Rate Range
With Glyphosate
Storm
4S
1.5 pt
1.5 pt
в– в– Storm is a 2:1 premix of bentazon (Basagran) plus acifluorfen (Ultra Blazer) for control of broadleaf weeds. The recommended rate of Storm (1ВЅ pt) is equivalent to 1 pint of Basagran and 1 pint of Ultra Blazer.
в– в– Site of action: group 14 (acifluorfen), group 6 (bentazon). See pages 14-15.
в– в– Apply Storm in a spray volume of 10 to 20 gpa. Use a minimum pressure of 40 psi. Increasing the spray volume (up
to 50 gpa) will improve control when crop and weed foliage is dense.
в– в– Apply Storm with COC (1 to 2 pints/A), UAN (1/2 to 1 gallon/A), or NIS (1 to 2 pints/100 gallons), depending upon
weed species present and other herbicide in the mixture. See label for specific directions.
в– в– Apply early when weeds are small (2 to 4 inches) for best results. Control is reduced when weeds exceed maximum
size stated on the label.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Ultra Blazer
2L
0.5 - 1.5 pt
0.5 - 1.5 pt
в– в– Ultra Blazer (acifluorfen) is a contact herbicide that controls many annual broadleaf weeds, including pigweed,
waterhemp, annual morningglory, common ragweed, and black nightshade. Control of giant ragweed is variable.
Cocklebur, velvetleaf, and lambsquarters are not adequately controlled.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply when weeds are in the 2- to 4-inch stage and actively growing.
в– в– Standard adjuvant recommendation is NIS (1 to 2 pints per 100 gallons spray). Various rates and combinations of
surfactant or COC and UAN are allowed depending upon weed species and environmental conditions. Application
with COC will increase crop injury.
в– в– Apply in a spray volume of at least 20 gpa with a minimum pressure of 40 psi. Increasing spray volume (up to 50
gpa) will improve control when crop and weed foliage is dense.
в– в– Application in combination with Basagran will improve control of velvetleaf, cocklebur, giant ragweed and some
other weeds.
в– в– The addition of 2 fluid ounces of 2,4-DB will improve morningglory, giant ragweed, and cocklebur control.
в– в– Often causes soybean leaf burn. Soybeans usually recover within a few weeks.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
117
Soybeans: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate
Classic
25DF
0.25 - 0.75 oz
0.25 - 0.33 oz
в– в– Classic (chlorimuron) is a translocated sulfonylurea herbicide that controls many annual broadleaf weeds, including
velvetleaf, annual morningglory, burcucumber, pigweed, cocklebur, Pennsylvania smartweed, yellow nutsedge, and
ragweeds. Classic does not control lambsquarters or black nightshade, and control of giant ragweed that are 4 to
8 inches tall is variable. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply with NIS (0.125% v/v or greater) or COC (1% v/v) plus UAN (2 - 4 quarts/A) or AMS (2 - 4 lbs/A).. COC provides
better control than surfactant under hot, dry conditions and is suggested for control of pigweed and giant ragweed.
в– в– Most weeds up to 2 inches tall can be controlled with a rate of 1/2 ounce per acre. Rate increases with weed size
and leaf stage. Velvetleaf and common ragweed control require a minimum rate of 2/3 ounce per acre, and the
minimum rate for large giant ragweed and Jerusalem artichoke is 3/4 ounce per acre. Classic will control cocklebur
up to 12 inches tall at the rate of 3/4 ounce per acre.
в– в– May be applied with 1 to 2 fluid ounces of 2,4-DB for improved morningglory control. Soybean must be at least 8
inches tall before this mixture is applied.
в– в– Split applications of Classic 14 to 21 days apart will improve control of morningglory, giant ragweed, burcucumber,
and Jerusalem artichoke.
Soybeans
Herbicide
Formulation
Product Rate Range
With Glyphosate
Assure II/Targa
0.88EC
5 - 10 oz
5 - 10 oz
в– в– Assure II/Targa (quizalifop) is a translocated herbicide that controls many annual and perennial grasses, including
giant foxtail, johnsongrass, shattercane, quackgrass, and volunteer corn. Quizalifop is often less effective than
other postemergence grass herbicides for control of yellow foxtail, barnyardgrass, and crabgrass, especially in
mixtures with broadleaf herbicides.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Apply 7 to 8 ounces per acre for control of foxtails (2 to 8 inches tall), and fall panicum, barnyardgrass, and crabgrass (2 to 6 inches tall). Lower rates may be used for control of shattercane, seedling johnsongrass, and small
giant foxtail.
в– в– For perennial grass control, application is delayed until grass reaches a height of at least 4 to 10 inches, depending
upon the target weed. Two applications may be needed for perennial grass control.
в– в– Apply with COC (1 to 2 gallons/100 gallons spray) for best results. NIS (2 pints/100 gallons spray) may be used instead of crop oil if required in a mixture with other herbicides. Petroleum-based COCs are preferred over MSOs.
в– в– For control of volunteer glyphosate-resistant corn in Roundup Ready soybeans in mixtures with glyphosate, apply
the following rates based on corn size: up to 12 inches - 4 oz; 12-18 inches - 5 oz; 18 to 30 inches - 8 oz. The addition of NIS at the rate of 2 pints per 100 gallons spray is recommended in this mixture. If the glyphosate product
contains a surfactant package, add NIS at the rate of 1 pint per 100 gallons.
в– в– Apply in a spray volume of 10 to 40 gpa with a pressure of 25 to 60 psi.
в– в– A reduction in the control of grasses may occur when quizalifop is applied to moisture-stressed plants or mixed
with Classic, Harmony GT, or Basagran. The reduction due to mixing is not usually observed for volunteer corn,
giant foxtail, shattercane, and johnsongrass control, and no increase in Assure II/Targa rate is required for control
of these grasses in mixtures. To maintain control of other grasses, increase the Assure II/Targa rate by 2 ounces in
mixtures. Do not mix Assure II/Targa with Basagran, Classic, or Harmony GT when the target grass is barnyardgrass,
quackgrass, crabgrass, yellow foxtail, or wirestem muhly.
в– в– For sequential applications of Assure II/Targa and broadleaf herbicides, wait at least 24 hours after Assure II/Targa
application before applying the broadleaf herbicide. If the broadleaf herbicide is applied first, do not apply Assure
II/Targa until grass plants begin to develop new leaves.
в– в– When mixing with glyphosate products without an adjuvant, use NIS or COC at above rates. If glyphosate product
has an adjuvant, use NIS (1 pint/100 gallons). If conditions are dry, use COC (1 gallon/100 gallons).
118
Soybeans: Postemergence Herbicides — Systemic
Apply in a minimum spray volume of 10 gallons per acre at a minimum pressure of 25 psi.
May cause temporary yellowing and stunting of soybeans, especially when applied with COC.
Apply any time after the first trifoliate has opened, but no later than 60 days before soybean maturity.
Treating weeds under stress from abnormally cold or hot weather or dry soil conditions may result in only partial
control. To maintain effective control, delay application until stress passes and weeds resume active growth.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (4.25 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Soybeans
в– в– в– в– в– в– в– в– Herbicide
Formulation
Product Rate Range
With Glyphosate
Clethodim
Various
See labels.
Select Max 6 - 12 fl oz
Arrow 6 - 8 fl oz
Section 6 - 8 fl oz
в– в– Clethodim is a translocated herbicide for control of annual and perennial grasses, including foxtails, barnyardgrass,
fall panicum, johnsongrass, shattercane, quackgrass, and volunteer corn.
в– в– Clethodim is sold under various trade names, including Select, Arrow, Section, and Select Max.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Most clethodim products are 2 lb/gal formulations, and the rates are as follows: 6 oz/A when giant foxtail is 2 to 12
inches tall, shattercane and seedling johnsongrass are 4 to 10 inches tall, volunteer corn is 12 to 18 inches tall, and
most other annual grasses are 2 to 6 inches tall. A rate of 4 ounces per acre may be used to control volunteer corn
that is 4 to 12 inches tall. Lower rates may be used for control of small giant foxtail that are actively growing under
favorable environmental conditions.
в– в– Select Max should be applied at a rate of 9 to 12 oz/A for control of annual grasses less then 6 inches tall. Rate
should be increased to 14 to 16 oz/A for annual grasses more than 6 inches tall and perennial grasses.
в– в– Control of volunteer corn with Select Max when mixed with glyphosate: 6 oz/A for volunteer corn that is less than
12 inches tall, and 9 oz/A for corn that is 12 to 24 inches tall. Apply with AMS (8.5 to 17 lbs/100 gallons). Add surfactant if required by the glyphosate product label. Other clethodim products will not usually adequately control
volunteer corn when mixed with glyphosate unless applied with COC or MSO. Consult labels and local use guides
for more information on adjuvant types and rates.
в– в– Control of perennial grasses requires higher rates and possibly sequential applications. Application should be delayed until perennial grasses are at least 4 to 12 inches tall, depending upon the target weed.
в– в– Labels for most clethodim products (excluding Select Max) specify application with COC or MSO (1% v/v and not
less than 1 pint/A) in a spray volume of 10 to 40 gpa at a pressure of 30 to 60 psi. Do not apply with flood nozzles.
UAN or AMS can be added, and may improve control of some grasses.
в– в– When applied alone, the preferred adjuvants for Select Max are NIS (0.25%) and AMS (2.5 lbs/A). COC (1% v/v or 1
qt/A) can be substituted for NIS if required for other herbicides mixed with Select Max.
в– в– Mixing clethodim with broadleaf herbicides may reduce grass control, especially under dry conditions. Increasing
the clethodim rate can help maintain grass control in mixtures with broadleaf herbicides. When making separate
applications of grass and broadleaf herbicides, allow at least one day between applications if the grass herbicide is
applied first.
в– в– When mixing with glyphosate, adjuvants are handled differently on different labels. Add AMS (2.5 to 4 lb/A) when
using any clethodim product and glyphosate. Select Max - add NIS (0.25% v/v). Arrow or Section - add NIS (0.125%
v/v) or COC (0.5 - 1% v/v). If mixing with a loaded glyphosate product, see glyphosate label also.
Herbicide
Formulation
Product Rate Range
With Glyphosate
FirstRate
84DF
0.3 - 0.6 oz
0.3 - 0.6 oz
в– в– FirstRate (cloransulam-methyl) is a translocated sulfonamide herbicide than controls ragweeds, velvetleaf, annual
morningglory, and cocklebur. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
119
Soybeans: Postemergence Herbicides — Systemic
в– в– Apply with NIS (0.125 to 0.25% v/v) plus 28% UAN (2.5% v/v) or AMS (2 lbs/A); or with COC or MSO (1.2% v/v). COC
or MSO plus UAN or AMS can increase crop injury and should only be used under adverse weed control conditions.
The spray mix should include UAN or AMS if velvetleaf is a target weed.
в– в– Control of giant ragweed may be reduced when air temperature remains below 55 degrees for significant periods
within 2 days before or after application.
в– в– Apply in a spray volume of 10 to 40 gpa with a pressure of 20 to 40 psi.
в– в– Mixing FirstRate with a grass herbicide, especially Assure II or Fusion, may result in reduced grass control. Increase
the grass herbicide rate or apply separately to avoid this problem.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Fusion
2.66E
6 - 14 oz
6 - 12 oz
в– в– Fusion is a premix of fluazifop-P (Fusilade) plus fenoxaprop-ethyl, translocated herbicides that control annual and
perennial grasses, including foxtails, barnyardgrass, johnsongrass, shattercane, volunteer corn, and quackgrass.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Mixtures with Pursuit are labeled for control of volunteer corn and shattercane only.
в– в– When applied alone, the rate is 6 to 8 ounces per acre for control of foxtails, fall panicum, and many other annual
grasses, 6 ounces per acre for control of seedling johnsongrass and shattercane, and 4 to 6 ounces for volunteer corn. The lower rates may be used when grasses are actively growing and are at the earliest growth stages
indicated on the label, soybeans are planted in narrow rows or cultivation is planned, weed densities are light to
moderate, and COC is used. The Fusion rate may need to be increased to 12 ounces when mixed with broadleaf
herbicides, depending upon grass size and environmental conditions at the time of application.
в– в– The Fusion rate is 4 to 6 oz/A for control of volunteer glyphosate-resistant corn in Roundup Ready soybeans in mixtures with glyphosate. The 4 oz rate can be used only under the following conditions: favorable soil moisture and
humidity; volunteer corn is less than 12 inches tall; and COC (0.25% v/v) is used as the spray adjuvant. In mixtures
with glyphosate products that are formulated with a surfactant package, where COC is not used, apply the 6 oz Fusion rate.
Soybeans
Herbicide
Formulation
Product Rate Range
With Glyphosate
Fusilade DX
2E
6 - 12 oz
4 - 6 oz
в– в– Fusilade DX (fluazifop) is a translocated herbicide that controls annual and perennial grasses.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Mixtures with Pursuit and Classic are labeled for control of volunteer corn and shattercane only.
в– в– For sequential applications of Fusilade and broadleaf herbicides, the minimum time interval that must occur between applications varies with the herbicides sprayed and the order of application. See the label for additional
information.
в– в– Apply 12 oz per acre to actively growing giant foxtail (2 to 6 inches tall) or other annual grasses (2 to 4 inches tall)
before grass has tillered. The rate for shattercane is 6 to 8 ounces per acre, and the rate is 4 to 6 oz/A for volunteer
corn. Apply with COC (0.5 - 1.0% v/v) or NIS (0.25 - 0.5% v/v) in a minimum spray volume of 5 gallons per acre. UAN
can also be added.
в– в– The Fusilade rate is 4 to 6 oz/A for control of volunteer glyphosate-resistant corn in Roundup Ready soybeans in
mixtures with glyphosate. The 4 oz rate can be used only under the following conditions: favorable soil moisture
and humidity; volunteer corn is less than 12 inches tall; and COC (0.25% v/v) is used as the spray adjuvant. In mixtures with glyphosate products that are formulated with a surfactant package, where COC is not used, apply the 6
oz Fusion rate.
в– в– For perennial grass control, use 12 oz and delay application until grass reaches a height of at least 4 to 8 inches, depending upon the target weed. A second application of 8 ounces/A may be needed for complete control.
120
Soybeans: Postemergence Herbicides — Systemic
Soybeans
в– в– Can be applied at 8 to 14 ounces/A as a rescue treatment for control of giant foxtail up to 16 inches tall. Use 12 to 14
ounces/A if grass is drought-or temperature-stressed. Do not mix with broadleaf herbicides when applying rescue
treatments.
в– в– Do not mix with Classic, Harmony GT, or Synchrony STS if conditions are dry and target grasses include yellow
foxtail, barnyardgrass, or crabgrass.
в– в– For perennial grass control, application is delayed until grass reaches a height of at least 4 to 6 inches, depending
upon the target weed. Two applications may be needed for perennial grass control.
в– в– For sequential applications of Fusion and broadleaf herbicides, the minimum time interval that must occur between
applications varies with the herbicides sprayed and the order of application. See the label for additional information
on sequential applications.
в– в– Apply with COC (2 to 4 quarts/100 gallons spray) for best results. NIS (1 to 2 quarts/100 gallons spray) may be used
instead of crop oil if required in a mixture with other herbicides. Liquid nitrogen fertilizer can be added to the spray
mixture, but should not be used as a substitute for COC or surfactant.
в– в– Apply in 5 to 40 gpa at a spray pressure of 40 to 60 psi. Use 60 psi and a minimum volume of 20 gpa where grass
foliage is dense.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Poast
1.5E
12 - 24 oz 12 - 24 oz
Poast Plus
1E
12 - 36 oz
12 - 36 oz
в– в– Poast (sethoxydim) controls annual grasses and controls or suppresses perennial grasses. Poast Plus is a premix of
sethoxydim plus Dash.
в– в– Site of action: group 1 (see pages 14-15).
в– в– For control of most annual grasses, apply 16 ounces of Poast or 24 ounces of Poast plus before weeds are 8 inches
tall. Control of volunteer cereals (prior to overwintering) requires higher rates. The label allows for reductions in
rate when applied to small actively growing grass. Reduced-rate recommendations apply only to barnyardgrass, fall
panicum, giant and green foxtails, and volunteer corn. See label for more information.
в– в– Apply with 2 pints of oil concentrate or 1 pint of Dash per acre. Include UAN (1/2 to 1 gallon/A) or AMS (2 1/2 lb/A)
for control of crabgrass, volunteer corn, or volunteer wheat. When mixing with Basagran, include UAN or AMS in
the spray mix. Rates and additive recommendations vary when mixing with Basagran, depending upon the target
grasses. See label for more information.
в– в– Use a rate of 24 oz/A (Poast) or 36 oz/A (Poast Plus) as a rescue treatment for control of foxtails up to 16 inches tall,
barnyardgrass and fall panicum up to 12 inches tall, and crabgrass up to 8 inches tall. Add UAN or AMS for control
of crabgrass.
в– в– Poast and Poast Plus are generally less efп»їfective than other postemergence grass herbicides for perennial grass
control. Two applications may be necessary for perennial grass control.
в– в– Optimum spray volume is 10 gallons per acre, but spray volumes of 5 to 20 gallons per acre may be used. Apply
with a spray pressure of 40 to 60 psi.
в– в– Poor control may result when applied to weeds under stress from hot,dry conditions or herbicide injury.
в– в– When applied in mixture with a glyphosate product not loaded with an adjuvant system follow recomendations
above, but do not use MSO. If glyphosate product is loaded with an adjuvant system, see glyphosate label for adjuvant recommendations.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Pursuit
2S
4 oz
4 oz
в– в– Pursuit (imazethapyr) is a translocated imidazolinone herbicide that controls annual broadleaf weeds and controls or suppresses grasses. Pursuit also provides some residual control of grass and broadleaf weeds. Control of
common and giant ragweeds and lambsquarters is variable. Mixtures with reduced rates of Flexstar or Cobra will
improve control of ragweeds. Pursuit does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
121
Soybeans: Postemergence Herbicides — Systemic
Herbicide
Formulation
Product Rate Range
With Glyphosate
Raptor
1AS
4 - 5 oz
4 - 5 oz
в– в– Raptor (imazamox) is a translocated imidazolinone herbicide that controls annual broadleaf and grass weeds. Raptor generally provides better control of lambsquarters and annual grasses than Pursuit. Control of common and giant ragweeds and waterhemp is variable. Raptor provides a shorter period of residual control compared to Pursuit.
Raptor does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply with NIS (2 pints/100 gallons spray) or a COC (1% v/v) plus UAN (1 to 2 quarts per acre) or AMS (2 1/2
pounds/A). AMS is generally the preferred nitrogen source over UAN or 10-34-0. Control of large or drought- or
temperature-stressed weeds will be maximized when the higher rates of fertilizer are used in combination with a
seed oil-based COC (Meth Oil or Sun-It II, for example).
в– в– For control of most annual grass and broadleaf weeds, apply before weeds are 4 to 5 inches tall and before soybeans bloom.
в– в– Control may be reduced when weeds are growing slowly under cold or dry conditions. If possible, wait for rain and
resumption of active weed growth before applying Raptor. If air temperatures reach or stay below 50 F for 10 or
more hours, delay application for 48 hours from the time temperatures increase above 50 F.
в– в– Raptor is more injurious to soybeans than Pursuit. Internode shortening and/or temporary yellowing of plants may
occur following application, especially when applied with a COC or MSO.
в– в– Apply in a spray volume of at least 10 gallons per acre with a spray pressure of 20 to 40 psi. Flat fan spray nozzles
are recommended for adequate plant coverage.
в– в– When applied in mixture with glyphosate, always include AMS (4.5 - 17 lb/100 gal). Include NIS (0.25% v/v) if glyphosate product does not contain an adjuvant.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Synchrony XP
28.4%WDG
0.375 - 0.75 oz
0.375 oz
в– в– Synchrony XP is a premix of chlorimuron (Classic) plus thifensulfuron (Harmony GT). Rates higher than 0.375 oz/A
should be applied only on STS soybeans (sulfonylurea tolerant soybeans).
в– в– Site of action: group 2 (see pages 14-15).
Soybeans
в– в– Apply with NIS (2 pints/100 gallons spray) or a COC (1ВЅ to 2 pints/A) plus UAN (1 to 2 quarts per acre). AMS (2 1/2
pounds/A) may be substituted for liquid fertilizer in the spray mix. Control of large or drought-stressed weeds will be
maximized when the higher rates of fertilizer are used in combination with a seed oil-based COC (Meth Oil or Sun-It
II, for example).
в– в– For control of most annual grass and broadleaf weeds, apply before weeds are 3 inches tall and before soybeans
bloom. Pursuit should be applied before lambsquarters and morningglory are 2 inches tall. Cocklebur, pigweed,
shattercane, and seedling johnsongrass can be controlled up to 8 inches tall. For control or suppression of Jerusalem artichoke, apply when artichokes are 6 to 10 inches tall.
в– в– Control may be reduced when weeds are growing slowly under cold or dry conditions. If possible, wait for rain and
resumption of active weed growth before applying Pursuit. If air temperatures reach or stay below 50 F for 10 or
more hours, delay application for 48 hours from the time temperatures increase above 50 F.
в– в– Combinations of Pursuit plus thifensulfuron can cause severe injury and yield loss under environmental conditions
that predispose soybeans to herbicide injury.
в– в– Apply in a spray volume of at least 10 gallons per acre with a spray pressure of 20 to 40 psi. Flat fan spray nozzles
are recommended for adequate plant coverage. Allow 1 hour between application and rainfall.
в– в– Mixtures of Pursuit with postemergence grass herbicides are generally labeled for control of volunteer corn and
shattercane only.
в– в– When mixing with glyphosate, add NIS (0.25% v/v) and AMS (8.5 to 17 lb/100 gallons) if the glyphosate is not formulated with its own adjuvant. If the glyphosate has its own adjuvant system, just add AMS.
122
Soybeans
Soybeans: Postemergence Herbicides — Systemic
в– в– Synchrony applied at 0.75 oz/A controls many annual broadleaf weeds, including lambsquarters, velvetleaf, cocklebur, morningglory, burcucumber, pigweed, Pennsylvania smartweed, yellow nutsedge, and ragweeds. Control of
giant ragweed that are 4 to 8 inches tall is variable. Black nightshade is not controlled. Synchrony will suppress or
control small perennial sowthistle, dandelion, common milkweed, pokeweed, and Jerusalem artichoke. Does not
control group 2-resistant weeds.
в– в– Mixing with Cobra, Flexstar, or Reflex will improve control of giant ragweed, common ragweed, black nightshade,
and waterhemp.
в– в– Apply after the first trifoliate soybean leaves have opened but no later than 60 days before soybean maturity.
Weeds should be 2 to 4 inches tall and actively growing for best results. Cocklebur, pigweed, velvetleaf, and smartweed can be controlled up to 8 inches tall.
в– в– Apply with COC (1% v/v) plus an ammonium nitrogen fertilizer at the following rates: 28% - 2 to 4 quarts/A; 10-34-0 1 to 2 quarts/A; or ammonum sulfate - 2 to 4 pounds/A. Use the lower fertilizer rates for spray volumes of less than
15 gpa.
в– в– At a reduced rate of 0.375 oz/A, Synchrony STS can be applied to non-STS soybeans for control of small cocklebur,
pigweed, and sunflower and suppression of other weeds. Use NIS instead of COC on non-STS soybeans. This
Synchrony rate can be used on mixtures with Flexstar, FirstRate, or Harmony GT.
в– в– Apply in a minimum spray volume of 10 gpa at a pressure of at least 25 psi using flat fan nozzles.
в– в– Synchrony STS may reduce the activity of a grass herbicide in mixtures. Increase the rate of the grass herbicide or
apply separately to maintain effective control.
в– в– When mixing with glyphosate, add AMS (4.25 - 17 lb/100 gal). If allowed by the glyphosate label, the use of NIS
(0.25% v/v) may improve efficacy.
Herbicide
Formulation
Product Rate Range
With Glyphosate
Thifensulfuron (active ingredient)
Harmony SG
50DF
0.12 oz
Not labeled
Harass, Treaty
75DF
0.08 oz
в– в– Thifensulfuron is a translocated sulfonylurea herbicide that controls velvetleaf, pigweed, lambsquarters, and Pennsylvania smartweed. Thifensulfuron is often included in mixtures with other broadleaf herbicides to improve lambsquarter and velvetleaf control. Does not control group 2-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Treating weeds under stress from abnormally cold or hot weather or dry soil conditions may result in only partial
control. To maintain effective control, delay application until stress passes and weeds resume active growth.
в– в– Apply with 0.125 to 0.25 percent NIS (v/v) when weeds are less than 4 inches tall and actively growing. Liquid
nitrogen fertilizer or AMS should also be included in the spray mix at the following rates: 28% - 2 to 4 quarts/A; 1034-0 - 2 to 4 pints/A; or AMS - 2 to 4 pounds/A. Under dry conditions, thifensulfuron can be applied with COC, but
soybean injury is likely to be more severe. To avoid injury when mixing with other products, follow label directions
closely regarding spray additives.
в– в– Apply with flat fan nozzles in a spray volume of 10 to 25 gpa at a pressure of 25 to 60 psi.
в– в– Apply after the first trifoliate soybean leaf has fully expanded up to 60 days before harvest.
в– в– Application of thifensulfuron may cause temporary wilting, leaf yellowing, and/or growth retardation (shortened internode spacing). These symptoms are most likely to occur when applied during periods of hot and humid weather.
123
LibertyLink Soybeans — Postemergence Herbicides
Herbicide
Formulation
Product Rate Range
Cheetah Max
3L
26 - 42 oz
в– в– Cheetah Max is a premix of glufosinate (Liberty) and fomesafen (Flexstar) for postemergence use only on LibertyLink (glufosinate-resistant) soybeans. The addition of fomesafen to glyufosinate can improve control of emerged
waterhemp and Palmer amaranth, and provide some residual control of these weeds.
в– в– Site of action: group 10 (glufosinate); group 14 (fomesafen). See pages 14-15.
в– в– Controls many annual grass and broadleaf weeds up to 3 to 6 inches tall. Use rates: north of I-70 - 26 to 40 oz;
south of I-70 - 26 to 42 oz. Apply in a minimum spray volume of 15 gpa, and increase to 20 to 40 gpa in dense
weed/crop canopies.
в– в– Cheetah Max is most effective in a combined preemergence plus postemergence program, where the preemergence herbicide will provide control of grass and broadleaf weeds for several weeks to a month after soybean
planting. Cheetah Max is weak on barnyardgrass, crabgrass, and yellow foxtail, and these weeds should be controlled by the PRE herbicides or with the addition of a POST grass herbicide (clethodim, Fusion, etc).
в– в– Often causes temporary soybean leaf burn. Cheetah Max contains adjuvants, and use of additional adjuvant will
increase the risk of crop injury.
в– в– Apply prior to bloom stage.
Soybeans
Herbicide
Formulation
Product Rate Range
Liberty 280 SL/Cheetah
2.34L
29 - 36 oz
в– в– Liberty/Cheetah (glufosinate) is a contact, broad-spectrum herbicide for postemergence use only on LibertyLink
(glufosinate-resistant) soybeans.
в– в– Site of action: group 10 (see pages 14-15).
в– в– Controls many annual grass and broadleaf weeds up to 3 to 6 inches tall when applied at a rate of 29 oz/A. Two
postemergence applications are allowed, but the total amount of Liberty/Cheetah per season (burndown + POST)
should not exceed 65 oz/A.
в– в– Liberty/Cheetah is most effective in a combined preemergence plus postemergence program, where the preemergence herbicide will provide control of grass and broadleaf weeds for several weeks to a month after soybean
planting. The preemergence herbicide should have substantial activity on lambsquarters, giant ragweed, waterhemp, marestail, and velvetleaf. Liberty/Cheetah is weak on barnyardgrass, crabgrass, and yellow foxtail, and
these weeds should be controlled by the PRE herbicides or with the addition of a POST grass herbicide (clethodim,
Fusion, etc).
в– в– Controls ragweed and marestail resistant to group 2 and/or 9.. For most effective control, apply when weeds are 4
to 6 inches tall. A second application (approximately 3 weeks later) will be necessary in dense giant ragweed infestations, where the preemergence herbicide fails to substantially reduce the weed population, or for control of large
marestail that were present at the time of soybean planting and escaped prior herbicide treatment.
в– в– Suppresses some perennial weeds, but has activity on above-ground growth only. Regrowth of perennials may
require a second application.
в– в– Activity on certain weeds is enhanced by the addition of AMS. The Liberty/Cheetah label does not mention AMS
with regard to LibertyLink soybeans, but specifies the use of AMS (3 lbs/A, or 17 lbs/100 gallons) in postemergence
applications to LibertyLink corn. Liberty/Cheetah has typically been applied with AMS (8.5 lbs/100 gallons) in university research trials.
в– в– Apply after soybean emergence and prior to soybean bloom.
в– в– Apply in a minimum spray volume of 15 gpa. Use a volume of 20 to 40 gpa in dense weed/crop canopies. Apply
with a nozzle type and spray pressure that results in medium spray droplets (250 to 350 microns).
в– в– Glufosinate is most effective when applied under warm, sunny conditions. Effectiveness may be reduced if applied
when heavy dew, fog and mist/rain are present, or if weeds are under stress due to drought, cool temperatures,
or extended periods of cloudiness. To avoid reduced weed control, apply between dawn and two hours before
sunset.
124
Roundup Ready Soybeans: Postemergence Herbicides
Soybeans
Herbicide
Formulation
Product Rate Range
Extreme/Thunder Master
2.17L
3 pints
Tackle
4.128SL
1 quart
в– в– These products are premixes of imazethapyr (Pursuit) and glyphosate for postemergence plus residual grass and
broadleaf weed control in Roundup Ready soybeans. They do not provide residual control of group 2-resistant
weeds. See Pursuit and glyphosate description for guidelines and restrictions on use.
в– в– Site of action: group 2 (imazethapyr); group 9 (glyphosate). (see pages 14-15).
в– в– Can be more effective than glyphosate on black nightshade, due to the residual control of later-emerging nightshade plants.
в– в– Apply when weeds are less than 8 inches in height, with NIS (1 pint/100 gallons) plus AMS (2.5 lbs/A) or UAN (1 to 2
qts/A).
в– в– This herbicide mixture occasionally causes unacceptable crop injury. Do not apply more than once per growing
season.
Herbicide
Formulation
Product Rate Range
Flexstar GT
3.29L
3 - 4.5 pts/A
в– в– Flexstar GT is a premix of glyphosate and fomesafen (Flexstar) for postemergence application to Roundup Ready
soybeans. Can also be applied prior to soybean emergence for no-till burndown.
в– в– Site of action: group 9/14 (see pages 14-15).
в– в– Use rates: north of I-70 - 3 to 3.75 pts/A; south of I-70 - 3 to 4.5 pts. Rates of 3.75 to 4.5 pints will provide the most
consistent control of glyphosate-resistant common or giant ragweed. The label allows a reduction of rate to 2.375
pts/A in fields without glyphosate-resistant weeds, as long as weeds are less than 4 inches tall.
в– в– Flexstar GT contains adjuvants, and requires only the addition of AMS (8.5 to 17 lbs/100 gallons) in areas where
weeds are not resistant to glyphosate. The addition of COC or MSO (0.5 - 1% v/v) can improve control but also
increases leaf burn and other injury symptoms. Based on OSU research, the addition of COC or MSO is required for
effective control of glyphosate-resistant ragweeds or in other situations where it is necessary to maximize the activity of fomesafen.
в– в– Apply in a spray volume of 15 to 20 gpa with a pressure of 30 to 60 psi. Flat fan nozzles will result in the most effective control. Do not use air induction of other nozzles that deliver large spray droplets.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
0.56 - 1.5 lbs acid/A
в– в– Glyphosate is a nonselective, translocated herbicide that controls emerged annual and perennial grass and broadleaf weeds. Table 24 contains a list of currently available glyphosate products. Application rates, adjuvant recommendations, rainfast intervals, and other guidelines for use vary among glyphosate products, and users should
consult labels and local product use guides for more specific information.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Glyphosate can be applied broadcast to Roundup Ready soybeans before, during, or after planting and crop emergence. The postemergence application window, per most glyphosate labels, is from emergence (cracking) through
flowering, or the R2 stage of soybean development. Soybean development exceeds the R2 stage, or begins the R3
stage, when a pod at least 3/16 inch long appears at one of the four uppermost nodes on the main stem with a fullydeveloped leaf. Crop injury and reduced pod formation has been observed where glyphosate was applied in late
summer to soybeans that were past the R2 stage of growth.
в– в– The following management practices are most effective for minimizing the risk of glyphosate resistance in weeds,
maintaining adequate weed control, and preserving maximum crop yield: (1) start weed free at planting through
use of tillage or a preplant burndown herbicide application, which should include 2,4-D ester; (2) include residual
herbicides in the preplant application to reduce weed populations and help control tough weeds; (3) make the first
postemergence glyphosate application when weeds are less than about 6 inches tall; and (4) make a second postemergence glyphosate application about 3 weeks later as needed to control late-emerging weeds and weeds that
were not completely killed by the initial application.
125
Roundup Ready Soybeans: Postemergence Herbicides
Herbicide
Formulation
Sequence5.25L
в– в– Sequence is a premix of glyphosate plus s-metolachlor (Dual II Magnum) that can be applied postemergence to
Roundup Ready soybeans to provide control of emerged weeds and residual control of annual grasses, black nightshade, pigweed, Palmer amaranth, and waterhemp.
в– в– Apply 2.5 to 3.5 pints/A when soybeans are between cracking and the 3rd trifoliate stage. Add AMS (8.5 to 17
lbs/100 gallons) where concentration of Ca, Mg, and Mn in water exceeds 150 ppm, and to generally improve control of some weeds.
Soybeans
в– в– The general recommendation on most labels for the initial postemergence application is a rate of 0.75 lbs of
glyphosate acid per acre (lbs a.e./A) when weeds are less than 4 to 8 inches tall (see Table 24 for product rates).
University research indicates that weeds should be no larger than 6 to 8 inches tall at the time of postemergence
glyphosate application to avoid yield loss from weed interference. Rate should be increased to 1.1 to 1.5 lbs ae/A for
larger weeds or in fields with a history of poor glyphosate performance. Additional postemergence applications are
permitted, but the total glyphosate in all postemergence applications should not exceed 2.25 lbs ae/A.
в– в– For control of volunteer glyphosate-resistant corn in Roundup Ready soybeans, apply glyphosate with Assure II,
Targa, Fusion, Fusilade DX, or Select Max. Do not use other clethodim formulations (Select, Arrow, etc) or Poast
products in mixtures with glyphosate for control of glyphosate-resistant volunteer corn. Consult labels and local
recommendation guides for information on adjuvants and rates when mixing glyphosate with postemergence grass
herbicides.
в– в– Glyphosate resistance has developed in populations of marestail, Palmer amaranth, waterhemp, and common and
giant ragweed in Ohio, Indiana, and Illinois, and some lambsquarters populations appear to have become less sensitive to glyphosate. Consider use of a preemergence herbicide that provides residual control of these weeds, in
order to avoid use of herbicide programs consisting solely of multiple glyphosate applications. Applying a glyphosate rate of 1.5 lbs a.e./A when plants are small (less than 6 inches tall) can result in more consistently effective
control of populations that have developed a low level of resistance, especially when followed by anoth application
of glyphosate 3 weeks later. Alternative approaches will be necessary where the population has a higher level of
glyphsoate resistance, and in populations with resistance to both groups 2 and 9. For more detailed recommendations for control of these weeds, see the “Control of Problem Weeds” section in this guide.
в– в– In OSU and Purdue University research, use of all of the following strategies has resulted in most effective control
of dense giant ragweed populations: (1) apply a preplant herbicide treatment that includes 2,4-D ester, glyphosate,
and a residual herbicide with activity on giant ragweed; (2) make the first postmergence application of glyphosate at
1.5 lbs ae/A when giant ragweed are not more than 10 inches tall, and (3) follow with a second application of glyphosate at 0.75 lb ae/A approximately 3 weeks later.
в– в– Application of a combination of glyphosate plus FirstRate can improve control of marestail and giant ragweed.
However, university research indicates that many marestail populations in Ohio, Indiana, and Illinois are resistant to
group 2, and FirstRate will not improve control of these populations.
в– в– Annual morningglory, groundcherry, ladysthumb, velvetleaf, marestail, and Pennsylvania smartweed should be less
than 6 inches tall at the time of application.
в– в– Best control of perennials will occur at higher labeled rates. Application when perennials are in the bud to bloom
stage (or boot to seedhead for grasses) will provide the most complete control of the entire plant. Minimum size of
various perennial weeds for most effective control through the growing season: quackgrass, Canada thistle, wirestem muhly, and yellow nutsedge - 6 inches; field bindweed and common milkweed - 12 inches; johnsongrass and
hemp dogbane - 18 inches.
в– в– Apply in a spray volume of 5 to 20 gpa. Take precautions to reduce spray drift. Corn, soybeans, and other sensitive crops are likely to be growing in areas surrounding treated fields. Using 15 to 20 gpa and flat fan or drift-control
nozzles at low pressure will reduce the potential for spray drift.
в– в– The addition of AMS will improve control of velvetleaf and some other weeds. AMS will also improve control when
using hard water or when daytime air temperatures are 55 degrees or less.
126
Soybeans: Selective Application of Glyphosate
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
See comments
в– в– Glyphosate can be applied to weeds growing above the soybean canopy through selective applicators such as
rope-wicks or sponge wipers. This application is useful for control of volunteer corn, shattercane, johnsongrass,
hemp dogbane, and common milkweed. Table 24 contains a list of currently available glyphosate products.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Weeds should be at least 6 inches taller than the soybeans. Avoid contact of herbicide with the crop. Adjust equipment so that the lowest wiper contact is at least 2 inches above the soybeans.
в– в– For mixing instructions and equipment calibration, refer to directions on labels.
Soybeans
Soybeans: Harvest Aid
Herbicide
Formulation
Product Rate Range
Aim
2EC
1 - 1.5 oz
в– в– Aim (carfentrazone) can be applied prior to harvest of mature soybeans for dessication of velvetleaf, morningglory,
pigweeds, and other weeds. Apply at least 3 days before harvest.
в– в– Site of action: group 14 (see pages 14-15).
в– в– The total amount of Aim that can be applied to soybeans in one season, including preplant, postemergence, and
harvest aid treatments, cannot exceed 1.5 oz/A.
в– в– Use a spray volume that results in complete coverage of foliage. Apply with NIS (0.25% v/v) or a COC (1 to 2% v/v).
UAN or AMS may also be added.
Herbicide
Formulation
Product Rate Range
Gramoxone SL
2L
8 to 16 oz
Parazone
3SL
5.4 to 10.7 oz
в– в– Gramoxone and Parazone (paraquat) may be used for drying weeds in soybeans just before harvest. For indeterminate soybean varieties, apply when 65 percent of the seed pods have reached a mature brown color or when seed
moisture is 30 percent or less. For determinate varieties, apply when at least one-half of the leaves have dropped
and the rest of the leaves are turning yellow.
в– в– Site of action: group 22 (see pages 14-15).
в– в– Mature cocklebur and lambsquarters are tolerant of paraquat and may not desiccate completely.
в– в– For aerial application, use a spray volume of 5 gallons per acre; for ground application, use 20 gallons per acre.
Add NIS (0.25% v/v) or COC (1% v/v).
в– в– Apply at least 15 days before harvest. Do not graze or harvest for forage or hay.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
up to 1.5 lb acid/A (aerial application)
up to 3.7 lbs acid/A (ground application)
в– в– Table 24 contains a list of currently available glyphosate products. Application rates, adjuvant recommendations,
rainfast intervals, application parameters, and other guidelines for use vary among glyphosate products, and users
should consult labels and local product use guides for more specific information. The following comments are
meant as general guidelines for the use of glyphosate except where a product name is listed.
в– в– Can be applied as a preharvest treatment to control perennial and annual weeds in soybeans. Dessication from glyphosate application is less rapid than that from Gramoxone. Preharvest applications of glyphosate may provide a good
127
Soybeans: Harvest Aid
opportunity to control perennial weeds because their growth is undisturbed compared to postharvest applications.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Apply after pods have set and lost all green color, and at least 7 or 14 days before harvest, depending upon the
product used. Do not graze or harvest the treated crop for livestock feed (Roundup brand labels allow use of soybeans for livestock feed when harvested 14 to 25 days, depending upon rate, after the last preharvest application).
в– в– Do not use a preharvest glyphosate application in soybeans grown for seed, due to the potential for a reduction in
viability or vigor.
Soybeans
Herbicide
Formulation
Sharpen2.85SC
в– в– Sharpen (saflufenacil) can be applied broadcast at rates of 1 to 2 oz/A to soybeans that have reached physiological
maturity. Indeterminate varieties should have greater than 65% brown pods and greater than 70% leaf drop with
seed moisture of 30% or less. Determinate varieties should have greater than 50% leaf drop with the rest of the
leaves yellowing.
в– в– Site of action: group 14. See pages 14-15.
в– в– Allow 3 days between application and harvest. Optimum dessication can require up to 10 days.
в– в– Do not apply to soybeans grown for seed production. Do not graze or feed treated hay or straw.
в– в– Use a spray volume of at least 10 gpa (ground) or 5 gpa (aerial). Apply with MSO ((1% v/v) plus either AMS (8.5 to 15
lbs/100 gallons) or 28% (1.25 to 2.5% v/v). Increase volume as necessary to ensure adequate coverage.
128
Table 17. Rainfast Intervals and Spray Additive Recommendations for Postemergence Soybean
Herbicides
This table shows the required time interval between herbicide application and rainfall and summarizes label recommendations
for spray additives. Check herbicide labels for additive rates. Adjuvant key: NIS + nonionic surfactant; COC = crop oil concentrate;
MSO = methylated seed oil; UAN = urea ammonium nitrate solution; AMS = ammonium sulfate.
Soybeans
Herbicide
Rainfast
Interval
(hours)
Spray additives
Aim
1
NIS
Assure II/Targa
1
NIS, COC, OR MSO. COC is preferred.
Basagran
8
MSO, COC, UAN or AMS; or COC or MSO + UAN or AMS
Cadet
1
NIS, COC, or MSO. UAN or AMS can be added.
Cheetah Max
4
None specified on label
Classic
1
NIS, COC, MSO or NIS + UAN or 10-34-0
Clethodim
1
COC or MSO. UAN, AMS, or 10-34-0 may be added.
Cobra
1/2
MSO, COC or UAN. NIS may be used under conditions of high humidity.
Cobra + Classic
1
NIS
Extreme/Tackle/Thunder Master
1
NIS + UAN, 10-34-0 or AMS.
FirstRate
2
NIS, COC, or MSO, + UAN or AMS, or COC or MSO alone.
Flexstar/Rhythm
1
MSO, COC, or NIS + UAN or AMS
Fusilade DX
1
MSO, NIS or COC. UAN or 10-34-0 may be added.
Fusion
1
MSO, NIS or COC. UAN or AMS may be added.
Liberty/Cheetah
4
None specified on label.
Marvel
1
NIS, COC or MSO. UAN or AMS may be added.
Poast/Poast Plus
1
MSO, COC or Dash. UAN or AMS may be added.
Prefix
1
NIS
Pursuit
1
MSO, NIS or COC, + UAN, 10-34-0, or AMS.
Raptor
1
COC, MSO, or NIS + UAN, 10-34-0, or AMS
Reflex/Dawn
1
MSO, NIS or COC. UAN or 10-34-0 may be added.
Resource
1
MSO or COC. UAN OR AMS may be added to improve control of certain weeds.
Select Max
1
NIS + AMS. COC can be used instead of NIS in mixtures with broadleaf herbicides.
Storm
8
MSO, NIS, COC, or UAN.
Synchrony XP
1
MSO or COC + UAN, 10-34-0, or AMS.
Synchrony XP + Cobra
1
COC or MSO + UAN, 10-34-0, or AMS.
Thifensulfuron
1
NIS + UAN, 10-34-0, or AMS. COC may be used instead of NIS under dry conditions.
Torment
1
NIS, COC, or MSO + UAN or AMS
Ultra Blazer
4
NIS or COC. UAN or 10-34-0 may be added to improve control of certain weeds.
Vise
1
NIS
129
Table 18. Harvest and Feeding Intervals for Soybean Herbicides
Soybean Herbicides
Days to Harvest
Forage
Apply up to third trifoliate
Do not feed
Assure II/Targa
80
Do not feed
Basagran
30
30
Basagran + 2,4-DB
60
60
Basagran + thifensulfuron
60
Do not feed
Basagran + Reflex
Apply prior to bloom
Do not feed
Basagran + Cobra
90
Do not feed
Cadet
60
Do not feed
Cheetah Max
70
Do not feed
Apply 60 days before maturity
Do not feed
Clethodim
60
Do not feed
Cobra
45
Do not feed
Apply prior to bloom and 85 days before harvest
Do not feed
FirstRate
65
14
Flexstar/Rhythm/Flexstar GT
45
Do not feed
Fusilade DX
Apply prior to bloom
Do not feed
Fusion
Apply prior to bloom
Do not feed
Liberty/Cheetah
Apply prior to bloom.
Do not feed
Poast/Poast Plus
75
Do not feed1
Previx/Vise
90
Do not feed
Pursuit
85
Do not feed
Raptor
85 and apply prior to bloom
Do not feed
45
Do not feed
Apply prior to bloom
Do not feed
Resource
60
Do not feed
Storm
50
Do not feed
Synchrony XP
Apply 60 days before maturity
Do not feed
Thifensulfuron
60
Do not feed
Torment
85
Do not feed
Ultra Blazer
50
Do not feed
Aim
Classic
Extreme/Tackle/Thunder Master
Reflex/Dawn
Reflex + 2,4-DB
1Soybean hay may be fed.
Soybeans
Grain
130
Small Grains
Weed Management Strategies for Wheat
A healthy wheat crop competes well with weeds,
especially when production techniques result in an initial
uniform stand and when loss of stand due to winter
injury is minimal. Effective weed control and prevention of weed seed production in prior crops will reduce
the risk of weed problems in wheat. Wheat should be
planted into a weedfree seedbed accomplished with
tillage or burndown herbicides. Gramoxone, glyphosate,
and Sharpen are labeled for burndown application in
wheat anytime prior to wheat emergence. Sharpen can
control emerged marestail and provide residual control
following planting, but should be mixed with glyphosate
or Garmoxone for control of most other emerged weeds.
Some wheat fields can benefit greatly from herbicide
application in late fall or spring, and failure to scout
fields and take the appropriate measure can result in
yield loss and harvesting problems in these fields. The
weeds that appear above the wheat canopy late in the
season, such as ragweeds and Canada thistle, can often
be easily controlled with a spring herbicide treatment.
The most common weed problems in wheat include:
в– в– winter annual weeds, such as common chickweed,
purple deadnettle, shepherd’s-purse, and field pennycress. These weeds become established in the
fall along with the wheat, and can interfere with the
early development of wheat in spring. Dense populations of winter annual weeds should be controlled in
late fall or early spring to minimize interference with
wheat growth. Many of these weeds have emerged
by the time of no-till wheat planting, and can be controlled with glyphosate before wheat emerges.
в– в– wild garlic, due to the contamination of harvested
grain with its bulblets. Several herbicides are efп»їfective if applied in the spring after garlic has several
inches of new growth.
в– в– Canada thistle, which can greatly suppress wheat
growth due to its tendency to occur in dense patches. many wheat herbicides have some activity on
thistle, and can suppress it adequately through harvest if not applied too early in spring.
в– в– dandelion, which can interfere with wheat establishment in the fall and wheat growth in the spring.
Emerged dandelion should be controlled prior to
wheat planting with tillage or glyphosate.
в– в– summer annual broadleaf weeds, such as common
and giant ragweed, which can begin to emerge in
late March. A healthy wheat crop can adequately
suppress these weeds but herbicide application is
occasionally warranted.
в– в– It is essential to apply herbicides at the correct stage
of wheat growth to avoid crop injury. When wheat
has not yet reached the jointing stage, any herbicide
labeled can be safely applied. As wheat growth stage
advances past jointing and approaches the boot
stage, herbicide choices become much more limited.
Most herbicides can be applied in UAN when the
wheat is top-dressed. This may increase crop injury
somewhat, and some labels recommend adjusting
surfactant rates to minimize injury.
131
Table 19. Weed Response to Postemergence Herbicides in Small Grains
This table compares the relative effectiveness of herbicides on individual weeds. Ratings are based on labeled application rate
and weed size or growth stage. Performance may vary due to weather and soil conditions, or other variables. See pages 14-15 for
more information on herbicide site of action and a description of site of action groups.
Weed control rating:
9 = 90% to 100%; 8 = 80% to 90%; 7 = 70% to 80%; 6 = 60% to70%; - = less than 60% control.
Brome, downy
Ryegrass, annual
Chickweed, common
Deadnettle, purple
Henbit
Lettuce, wild or prickly
Marestail
Marestail (group 2-R)
Mustard species
Pennycress, field
Shepherdspurse
Buckwheat, wild
Lambsquarters, common
Pigweed
Ragweed, common
Ragweed, giant
Smartweed, ladysthumb
Garlic, wild
Thistle, Canada
14
-
-
-
-
-
6
6
6
-
-
6
7
6
6
7
8
6
-
-
-
-
14/15
8
6
6
8
-
6
6
6
-
-
6
7
6
-
-
-
-
-
-
-
-
Axial Star
2/4
-
-
-
9
-
-
-
6
-
-
7
-
-
6
-
-
8
8
6
-
-
Axial TBC
1/2
-
-
-
9
9
-
-
6
-
-
9
6
9
6
-
6
-
-
-
-
-
Axial XL
2
-
-
-
9
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
5/15
-
-
7
8
7
7
7
-
-
-
8
8
8
-
-
-
-
-
-
-
-
6
-
-
-
-
6
-
8
6
6
6
9
8
8
9
9
7
9
8
9
-
6
4/6
-
-
-
-
6
6
8
7
8
8
9
9
9
9
9
9
9
9
9
-
8
Curtail
4
-
-
-
-
-
-
-
9
8
8
9
9
9
9
9
9
9
9
8
-
9
Dicamba
4
-
-
-
-
6
-
6
8
8
8
6
6
8
9
9
9
9
9
9
-
6
Finesse/Report
Extra
4
9
-
-
-
9
9
9
8
8
-
9
9
9
8
9
9
8
-
7
6
7
6/27
-
-
-
-
8
9
9
9
9
9
9
9
9
8+
9
9
9
9
8+
-
6
Maverick
2
-
8
8
-
-
7
7
8
7
-
8
8
8
-
6
8
-
-
-
7
-
MCPA
4
-
-
-
-
-
-
-
9
8
8
9
9
9
8
9
9
9
9
7
-
-
Olympus
2
-
9
8
-
9
9
9
-
8
-
9
8
9
6
-
6
-
-
-
-
-
Orion
2/4
-
-
-
-
9
-
-
9
-
-
9
9
9
8
9
9
9
8
9
-
6
Peak
2
-
-
-
-
7
7
7
8
-
-
9
9
8
8
7
9
9
7
7
8
6
PowerFlex
2
-
9
8
9
9
7
7
6
6
-
9
9
8
7
8
9
-
-
7
-
-
Pulsar + MCPA
4
-
-
-
-
8
8
8
9
8
8
9
9
9
9
9
9
9
9
8
-
-
Starane
4
-
-
-
-
-
-
-
6
-
-
7
-
-
7
-
-
9
9
7
-
-
Stinger
4
-
-
-
-
-
-
-
8
9
9
-
-
-
9
-
-
9
9
8
-
9
Tribenuron
2
-
-
-
-
9
9
9
9
-
-
9
9
8
8
9
9
-
-
8
6
8
Tribenuron + thifensulfuron
2
-
-
-
-
9
8
9
8
7
-
9
9
9
8
9
9
-
-
9
9
7
WideMatch
4
-
-
-
-
-
-
-
8
9
9
7
-
-
9
-
-
9
9
7
-
8
2,4-D
4
-
-
-
-
-
-
-
9
8
8
9
9
9
-
9
9
9
9
6
7
7
Aim
Anthem Flex
Axiom
Bromoxynil
Cleansweep D or M
Huskie
Small Grains
Cheat
Perennial
Bluegrass, annual
Summer annual
Site of action
Winter annual
132
Small Grains: Wheat Only
Herbicide
Formulation
Product Rate Range
Anthem Flex
4 SE
2 - 4.5 oz
в– в– Anthem Flex is a premix of pyroxasulfone (Zidua) and carfentrazone (Aim) that controls annual ryegrass, foxtails, and
barnyardgrass, and a few broadleaf weeds in wheat. Provides only residual control of grasses.
в– в– Site of action: group 15 - pyroxasulfone; group 14 - carfentrazone (see pages 14-15).
в– в– Apply delayed preemergence (80% of germinated wheat seeds with at least 1/2 inch shoot through wheat spiking)
or early postemergence (spiking up to 4th tiller growth stage). See label for rates based on timing and soil type.
в– в– Wheat seed should be planted between 1 and 1.5 inches deep. Avoid preeemergence application if 0.25 inches of
rain or more is expected within 48 hours of application. Do not incorporate.
в– в– Do not apply preplant or preemergence to broadcast seeded wheat.
Small Grains
Herbicide
Formulation
Product Rate Range
Axial Star
1.15L
16.4 oz
в– в– Axial Star is a premix of pinoxaden (Axial) and fluroxypyr (Starane) that controls annual ryegrass, foxtails, and barnyardgrass, and a few broadleaf weeds in wheat. Mix with other broadleaf herbicides to expand the spectrum of
broadleaf weed control.
в– в– Site of action: group 1 - pinoxaden); group 4 - fluroxypyr (see pages 14-15).
в– в– Apply when wheat is in the 2-leaf to pre-boot stage, and when grass weeds have 1 to 5 leaves and less than 3 tillers.
в– в– Do not plant soybeans and other crops within 4 months after application.
в– в– Can be mixed with most other broadleaf herbicides used in wheat. See label for more information.
Herbicide
Formulation
Product Rate Range
Axial XL
0.42L
16.4 oz
в– в– Axial XL (pinoxaden) controls annual ryegrass, foxtails, and barnyardgrass in wheat.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Apply when wheat is in the 2-leaf to pre-boot stage, and when grass weeds have 1 to 5 leaves and less than 3 tillers.
в– в– Do not plant soybeans and most other crops for 120 days after application.
в– в– Can be mixed with most other broadleaf herbicides used in wheat. See label for more information.
Herbicide
Formulation
Product Rate Range
Axial TBC
0.84L
8.85 oz
в– в– Axial TBC is a premix of florasulam and pinoxaden that controls annual ryegrass, foxtails, barnyardgrass, and some
broadleaf weeds in wheat and barley. The label specifies the addition of MCPA or other herbicide to improve
broadleaf weed control.
в– в– Site of action: group 1 (pinoxaden); group 2 (florasulam). See pages 14-15.
в– в– Apply when wheat is in the 3-leaf to boot stage, and when grass weeds have 1 to 5 leaves and less than 3 tillers.
в– в– Apply with Adigor Adjuvant at the rate of 9.6 oz/A. Can be applied in a spray solution containing up to 50% UAN or
other nitrogen fertilizer.
в– в– Allow 9 months between application and soybean planting.
Herbicide
Formulation
Product Rate Range
Axiom
68DF
4 - 10 oz
в– в– Axiom is a premix of metribuzin and flufenacet that can be applied early postemergence in wheat to control small
winter annual grass and broadleaf weeds. Axiom provides limited residual weed control also.
в– в– Site of action: group 5/15 (see pages 14-15).
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Small Grains: Wheat Only
в– в– Apply in the fall from spike to 3-leaf stage of wheat, and prior to the 1-leaf stage of weeds. For best results, use tillage or burndown herbicides to ensure that wheat is weedfree at the time of planting.
в– в– Some wheat varieties are sensitive to Axiom. Check the label and with seed supplier for information on tolerance
prior to using.
Herbicide
Formulation
Product Rate Range
Curtail
2.38L
1 - 2 2/3 pts
в– в– Curtail is a premix of clopyralid (Stinger) plus 2,4-D amine that controls many annual weeds in wheat, including ragweeds, lambsquarters, mustard species, field pennycress, and shepherd's-purse.
в– в– Curtail controls Canada thistle, but will be less effective than Stinger for long-term thistle control. For best thistle
control, apply after the majority of the weed's basal leaves have emerged from the soil, but before bud stage.
Other perennials controlled or suppressed include sowthistle, dandelion, and curly dock.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply in the spring to actively growing wheat after 4 leaves have unfolded on the main stem. Maximum rates based
on wheat growth stage and weed size are as follows: 2 2/3 pints - before jointing, weeds up to 12 inches tall; 1.5
pints - before boot stage, weeds up to 10 inches tall; and 1 pint - before boot stage, weeds less than 6 inches tall.
в– в– Apply in a spray volume of at least 10 gpa and increase volume where the weed/crop canopy is dense.
в– в– Curtail can be applied in UAN.
в– в– Allow 6 to 8 hours between application and rainfall.
в– в– Do not apply Curtail where double-crop soybeans will be planted after wheat harvest or a legume will be seeded
into standing wheat.
в– в– Do not harvest hay from treated fields.
в– в– Crop rotation restrictions: grasses - 30 days after application; alfalfa, soybeans - 10 1/2 months; clovers - 18 months.
Herbicide
Formulation
Product Rate Range
Maverick
75DF
2/3 oz
в– в– Maverick (sulfosulfuron) can be applied in the fall to emerged wheat to suppress or control grass weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Maverick will suppress or control downy bromegrass and cheat, which are winter annual grasses. Most effective
application timing is postemergence in the fall when these grasses are in the 2 to 3-leaf stage. This treatment will
also suppress quackgrass. Maverick provides residual control of some winter annual broadleaf weeds, but may not
adequately control emerged broadleaf weeds.
в– в– Apply with NIS (2 qts/100 gallons).
в– в– The optimum pH of the spray solution is 6.0 to 8.0 when using Maverick.
в– в– OSU recommends the use of an STS soybean variety where double-crop soybeans will be planted after wheat harvest. The label specifies the following with regard to rotation to soybean: 1) STS soybeans can be planted 3 months
Small Grains
Herbicide
Formulation
Product Rate Range
Dicamba + 2,4-D premix
3.87L
0.5 - 1 pt
в– в– This product is available from various manufacturers, and product names and rates vary. Controls broadleaf weeds
in wheat.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply 0.5 to 1 pint per acre in the spring after tillering and prior to the joint stage.
в– в– Rates up to 1 1/3 pints per acre can be applied in the fall after wheat begins to tiller for suppression of perennial
weeds such as dandelion. Apply following a frost but before a killing freeze. Periods of extended stress such as
cold and wet weather may increase the risk of crop injury. Do not apply in the fall unless the user is willing to accept the risk of of crop injury.
в– в– Apply in a spray volume of at least 5 gpa, and increase spray volume in dense or tall vegetation.
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Small Grains: Wheat Only
after application where soil pH is less than 6.5 and at least 30 inches of rain has occurred between application and
soybean planting; 2) non-STS soybeans can be planted 5 months after application where soil pH is less than 6.5
and at least 30 inches of rain has occurred; and 3) non-STS soybeans can be planted 12 months after application
where soil pH is less than 7.5 and at least 24 inches of rain has occurred.
в– в– Any crop other than soybeans or wheat should be planted no sooner than 3 months after Maverick application and
only after the completion of a successful field bioassay.
Small Grains
Herbicide
Formulation
Product Rate Range
Metribuzin
75DF
0.75 - 2 oz
в– в– Metribuzin (Dimetric, Tricor) can be applied in the fall to emerged wheat to help control winter annual weeds.
в– в– Site of action: group 5 (see pages 14-15).
в– в– Wheat should be in the 2-leaf to 2-tiller stage and actively growing at the time of application. Rate varies with soil
type.
в– в– Wheat varieties vary in their tolerance to metribuzin. Consult the label for a list of varieties that are approved for
use with metribuzin.
в– в– Can be applied with other herbicides labeled for fall application, including Harmony Extra. Consult labels for all
precautions before application of any herbicide combination.
в– в– Do not apply with fertilizer solution.
в– в– Crop injury may occur if metribuzin is applied: 1) when the crop is under stress from frost damage, drought, or excessive moisture; 2) to soils with pH greater than 7.7, or 3) to fields where wheat is planted less than 1 inch deep.
Herbicide
Formulation
Product Rate Range
Olympus
70WDG
0.6 - 0.9 oz
в– в– Olympus (propoxycarbazone-sodium) controls downy brome, cheat, and mustard species. Olympus should be
mixed with other herbicide(s) to control a broader spectrum of broadleaf weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Can be applied from preemergence in the fall through the spring before jointing.
в– в– Apply with NIS (0.25 to 0.5% v/v). When applied using UAN as the carrier, the NIS rate is 0.25% v/v. Temporary crop
injury, including reduced growth, discoloration, and leaf burn, may occur when fertilizer is the carrier. Do not use
adjuvants that result in a spray solution pH of less than 5.
в– в– Can be mixed with Huskie, Axiom, Harmony GT, Harmony Extra, dicamba, or bromoxynil.
в– в– Do not plant crops other than wheat within 4 months after application. Conduct field bioassay before rotating to
any other crop - see label for guidelines.
Herbicide
Formulation
Product Rate Range
PowerFlex
7.5DF
3.5 oz
в– в– PowerFlex (pyroxsulam) controls downy brome, cheat, and Italian ryegrass, and some winter annual broadleaf
weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply in the fall or spring, when wheat is in the 3-leaf to jointing stage. Most effective control results from treatment
of winter annual grasses in the fall at the 2-leaf to 2-tiller stage of growth, and when broadleaf weeds are no more
than 2 inches tall or in diameter.
в– в– Apply with NIS (0.25% to 0.50% v/v) or COC (1 to 1.25% v/v). When using NIS, UAN (1-2 qt/A) or AMS (3 lbs/acre)
may be added to enhance control. Potential for crop injury is increased with the use COC. Do not use additives
that lower the spray solution below a pH of 6.0.
в– в– PowerFlex may be applied in spray solutions containing nitrogen fertilizer solution (UAN). The spray solution should
not consist of more than 50% UAN and should not exceed 30 pounds of actual nitrogen per acre. When PowerFlex
135
Small Grains: Wheat Only
is applied in spray solutions containing UAN, use NIS at a maximum of 0.25% v/v, instead of COC or MSO. Temporary crop injury may result when liquid nitrogen is used as the spray carrier.
в– в– A separate application of nitrogen fertilizer solution made 7 days before or after a PowerFlex application may result
in transient leaf burn or stunting. Do not make a liquid fertilizer application during this period unless the risk of crop
response is acceptable.
в– в– Grass control can be reduced if PowerFlex is mixed with dicamba or amine formulations of 2,4-D or MCPA.
в– в– Allow 3 months between application and soybean planting. Where Powerflex is applied in fall or anytime prior to
February, do not plant soybeans until after April 30.
Herbicide
Formulation
Product Rate Range
Pulsar
1.67L
8.3 - 12.5 oz
в– в– Pulsar is a premix of fluroxypyr (Starane) and dicamba for control of broadleaf weeds in wheat and barley. Pulsar
applied alone has a fairly narrow spectrum of control, and should generally be mixed with MCPA ester or another
broadleaf herbicide.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply before the jointing stage of wheat (label does not specify whether fall application is allowed).
в– в– Pulsar can be applied with NIS (0.125% to 0.25% v/v) to improve control under less than optimum environmental
conditions.Can be applied in a spray solution containing up to 50% nitrogen fertilizer solution.
в– в– Allow 9 months between application and soybean planting.
в– в– Do not graze or feed forage or hay from treated areas to livestock. Dry-harvested straw may be used for bedding
and feed.
Small Grains
Herbicide
Formulation
Product Rate Range
Tribenuron methyl (active ingredient)
Express TotalSol
50DF
0.25 - 0.5 oz
Nuance, Victory
75WDG
1/6 - 1/3 oz
в– в– Tribenuron methyl controls annual broadleaf weeds, including common chickweed, lambsquarters, and field pennycress, and provides partial control of Canada thistle, dandelion, shepherdspurse, and other mustard species.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Can be mixed with bromoxynil, 2,4-D or MCPA for improved control of Canada thistle, ragweeds, dandelion, and
other broadleaf weeds. Ester formulations have provided better results than amines.
в– в– Apply after wheat is in the 2-leaf stage but before the flag leaf is visible. Apply when annual weeds are less than 4
inches tall or wide (rosettes). Allow 45 days between application and harvest.
в– в– To reduce the risk of crop injury, mix tribenuron with 2,4-D and apply after crop has reached the tillering stage of
growth.
в– в– To control or suppress Canada thistle, apply the higher rate to actively growing thistle plants that are 4 to 8 inches
tall with 2 to 6 inches of new growth.
в– в– When applying in water, add 0.06 to 0.50% v/v NIS (1/2 to 4 pints per 100 gallons of water). When applying in liquid
fertilizer, add 0.06 to 0.25% NIS. Temporary crop yellowing and stunting may occur when applied in liquid fertilizer.
This injury is occasionally severe, and risk of severe injury may increase under saturated soil conditions.
в– в– For flat-fan nozzles, apply in a spray volume of at least 5 gallons per acre. For flood nozzles on spacings of 30, 40,
or 60 inches, maintain minimum spray volumes of 10, 13, or 20 gallons per acre, respectively.
в– в– Forage legumes, grasses, and soybeans may be planted 45 days after application.
136
Small Grains
Small Grains: Oats and Wheat
Herbicide
Formulation
Product Rate Range
2,4-D Amine
Various
0.25 - 1 lb ai/A
2,4-D Ester
MCPA Amine
4 lb/gal
1/2 - 2 pt
MCPA Ester 1/2 - 1ВЅ pt
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply in the spring after full tiller. Labels vary with regard to the wheat stage when 2,4-D should no longer be applied. Weedar and Weedone labels specify application before wheat is forming joints in the stem. Labels of some
other 2,4-D products allow application after jointing but before early boot. The risk of injury and yield loss increases
when applied after jointing. Amine formulations are less likely to injure the crop than ester formulations, and use of
fertilizer solution as the spray carrier may increase the risk of injury. To minimize the risk of injury after jointing, use
water as the carrier and do not apply more than 0.25 lb ai/A of ester or 0.5 lb ai/A of amine.
в– в– Application prior to wheat emergence can cause crop injury and stand loss.
в– в– MCPA is less likely than 2,4-D to injure oats. Do not apply 2,4-D ester to oats.
в– в– 2,4-D and MCPA are translocated herbicides that control many winter and summer annual weeds, but are weak on
chickweed, henbit, and purple deadnettle. Expect some suppression of early-emerging perennial broadleaf weeds.
в– в– 2,4-D may provide some suppression of wild garlic, especially the ester formulation. Apply 0.75 lb ai/A of 2,4-D
ester when wild garlic plants are small.
в– в– In wheat, 2,4-D or MCPA may be applied with 1/4 pint of dicamba (4 lb/gallon formulations) for improved control of
some weeds.
в– в– To control problem weeds at harvest, apply 0.5 to 1.0 lb ai/A per acre of 2,4-D during the hard dough stage.
в– в– Do not forage or graze within 7 days (MCPA) or 2 weeks (2,4-D) of treatment. Do not feed treated straw to livestock
when 2,4-D is applied as a preharvest treatment.
Herbicide
Formulation
Product Rate Range
Aim
2EC
0.5 - 2 oz
в– в– Aim (carfentrazone-ethyl) is a contact herbicide that controls a limited number of small summer and winter annual
weeds. Aim is not effective on biennial or perennial weeds.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Apply Aim in the fall or spring before jointing when weeds are less than 4 inches tall and rosettes are less than 3
inches across.
в– в– Apply with NIS (0.25% v/v). UAN (2 to 4 gallons/100 gallons) or AMS (2 to 4 lbs/A) can be added if recommended for
use with other herbicides in a mix with Aim.
в– в– Apply Aim in a spray volume of 10 to 20 gpa with a pressure of 20 to 40 psi. Flat fan nozzles are recommended for
adequate spray coverage.
в– в– Add Aim to the spray tank before adding other products.
Herbicide
Formulation
Product Rate Range
Bromoxynil
2S
1 - 2 pt
в– в– Bromoxynil is a contact herbicide that controls annual broadleaf weeds. Product names include Buctril, Moxy, Broclean, and Bronate among others.
в– в– Site of action: group 6 (see pages 14-15).
в– в– In fall-seeded small grains, apply in the fall or spring, but before the boot stage.
в– в– In spring-seeded oats, apply from emergence up to the boot stage.
в– в– For best results, apply before weeds are in the 4-leaf stage or are 2 inches tall, or before rosettes exceed 1 inch in
diameter.
в– в– Very safe on small grains, but slight leaf burn may occur occasionally.
137
Small Grains: Oats and Wheat
в– в– May be applied with dicamba, 2,4-D, MCPA, Express, or Harmony Extra. Maximum growth stage at the time of application and spray additive recommendations vary with the other herbicide in the mixture. Follow label directions
to avoid injury to the crop.
в– в– UAN may be used as the spray carrier early in the spring, but this will increase leaf burn. Do not use fertilizer as the
carrier after jointing.
в– в– Do not graze treated fields for 30 days after application.
Herbicide
Formulation
Product Rate Range
Callisto
4L
6 oz (preemergence)
3 oz (postemergence)
в– в– Callisto (mesotrione) can be applied preemergence or postemergence in oats for control of broadleaf weeds. Do
not apply to wheat or other small grains.
в– в– Site of action: group 27 (see pages 14-15).
в– в– Apply when weeds are less than 5 inches tall.
в– в– Control of emerged weeds requires the addition of COC (1% v/v) or NIS (0.25% v/v). UAN (2.5% v/v) or AMS (8.5
lbs/100 gallons) may be added, but increases the risk of injury.
в– в– Postemergence applications may cause temporary crop injury, including leaf bleaching and burn, and stunting if
injury is extreme.
Herbicide
Formulation
Product Rate Range
Dicamba
4L
2 - 4 oz
в– в– Dicamba is sold under various trade names, including Banvel, Oracle, and Sterling Blue. Dicamba is a translocated
herbicide that controls annual and winter annual broadleaf weeds, and helps suppress perennial broadleaf weeds.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Can be applied in the fall or spring after emergence of fall-seeded wheat, but before jointing. Application prior to
wheat emergence can cause crop injury and stand loss. Can be applied prior to planting, but allow 10 days between application and planting for each 0.25 lb active ingredient dicamba applied.
в– в– In spring oats, apply a maximum of 0.12 lb ai/A before oats exceed the 5-leaf stage.
в– в– For best results, apply when weeds are small and actively growing.
в– в– Dicamba is more effective on Canada thistle and smartweed than 2,4-D or MCPA. For better control of some weeds,
Banvel may be mixed with up to 2 pints of 2,4-D amine or 1ВЅ pints of 2,4-D ester.
в– в– Do not graze or harvest for dairy feed before ensilage (milk) stage.
Small Grains
Herbicide
Formulation
Product Rate Range
Cleansweep D
4.25L
1 - 1.5 pts
Cleansweep M
4L
1 - 1.5 pts
в– в– These products are mixtures of bromoxynil, fluroxypyr, and either 2,4-D (Cleansweep D) or MCPA (CleansweepM)
for control of annual broadleaf weeds in wheat, oats, and barley. Supression of some perennial broadleaf weeds is
also possible.
в– в– Site of action: group 6 (bromxynil), group 4 (fluroxypyr, 2,4-D, MCPA. See pages 14-15.
в– в– Cleansweep D: apply from the fully-tillered stage of growth until (but not including) the jointing stage.
в– в– Cleansweep M: apply from the 2-leaf crop stage up to and including flag leaf emergence.
в– в– Weed control is maximized by application when air temperatures are between 55 and 75 degrees, and reduced
activity can occur below 45 or above 85 degrees. Weed control and crop tolerance may be reduced if frost occurs
within 3 days before or after application.
в– в– Allow 1 hour between application and rainfall.
в– в– Labels for these products do not indicate whether product can be applied in the fall or applied using 28% UAN as
the spray carrier. An adjuvant can be added, but labels do not otherwise specify rate or type of adjuvant.
в– в– Allow 4 months between application and planting soybeans or crops other than small grains.
138
Small Grains: Oats and Wheat
Small Grains
Herbicide
Formulation
Product Rate Range
Finesse/Report Extra
75WDG
0.2 - 0.5 oz
в– в– Finesse/Report Extra is a premix of chlorsulfuron and metsulfuron methyl that can be applied preplant, preemergence or postemergence for control or suppression of downy brome, cheat, and annual ryegrass. Postemergence
applications control or suppress these same grasses and also annual annual bluegrass, along with a number of
winter annual broadleaf weeds.
в– в– Postemergence applications should be made in the fall for most effective control of grasses, and to avoid crop rotation problems. Apply after the majority of the weeds have emerged, when the crop is in at least the 1-leaf stage.
в– в– Chlorsulfuron is a long-residual sulfonylurea herbicide. Consider rotation guidelines prior to using this product. STS
soybeans can be planted 6 months after application. Field corn and non-STS soybeans can be planted 18 months
after application.
в– в– Apply with flat fan (at least 3 gpa) or low-volume flood nozzles (at least 10 gpa) for optimum distribution and coverage. Include a NIS (0.125 to 0.5% v/v).
в– в– Can be applied using UAN as the spray carrier, and the rate of UAN determines the rate of surfactant. Consult the
label for more information.
в– в– The field can be grazed anytime after herbicide application.
Herbicide
Formulation
Product Rate Range
Huskie
2.47L
13.5 - 15 oz
в– в– Huskie (bromoxynil plus pyrasulfotole) controls winter and summer annual broadleaf weeds in wheat, oats, barley,
rye, and triticale.
в– в– Site of action: group 6 (bromoxynil); group 27 (pyrasulfotole). See pages 14-15.
в– в– Apply in fall or spring after the crop reaches the 1-leaf stage, and up to flag leaf emergence. Weeds should be no
larger than the 4- to 6-leaf stage, or 4 inches in diameter, depending upon species.
в– в– Apply with AMS (0.5 to 1 lb/A) or UAN (1 to 2 qts/A) for most consistently effective weed control. Can be applied
using nitrogen fertilizer solution as the spray carrier. The fertilizer solution should not exceed 50% nitrogen, and the
nitrogen rate should not exceed 30 lbs/A.
в– в– Should generally be applied in a spray volume of at least 10 gpa, but this can be reduced to as low as 5 gpa when
conditions are ideal for weed control (small weeds, favorable environment). Use nozzles and spray pressure that
result in medium spray droplets. Do not apply with floodjet or cone nozzles.
в– в– Allow 1 hour between application and rainfall.
в– в– Do not graze or harvest forage within 25 days after application. Grain and straw can be harvested 60 days after
application.
в– в– Allow 4 months between application and planting soybeans.
Herbicide
Formulation
Product Rate Range
Orion
2.37L
17 oz
в– в– Orion (MCPA plus florasulam) controls annual broadleaf weeds in wheat, oats, rye, and triticale. Weeds controlled
include chickweed, mustard species, common ragweed, and lambsquarters.
в– в– Site of action: group 2 (florasulam); group 4 (MCPA). See pages 14-15.
в– в– Apply early postemergence when the crop is in the 3-leaf to joint stage. Weeds will be most effectively controlled
when in the seedling stage and actively growing.
в– в– This product does not require use of an adjuvant. Apply in a spray volume of at least 10 gpa. Increasing the spray
volume may improve control where the crop and weed canopy is dense.
в– в– Allow 4 hours between application and rainfall.
в– в– Do not graze for 7 days after application. Apply at least 60 days before harvest.
в– в– Crop rotation restrictions: grasses - 0.5 months; corn - 3 months; alfalfa, soybeans - 9 months; clovers - 12 months.
139
Small Grains: Oats and Wheat
Herbicide
Formulation
Product Rate Range
Peak
57DF
1/2 oz (1 packet per 6 acres)
в– в– Peak (prosulfuron) controls annual broadleaf weeds in wheat, oats, rye, and some other small grains. Weeds
controlled include chickweed, wild garlic, mustard species, and common ragweed (except group 2-resistant
biotypes). Peak will suppress Canada thistle.
в– в– Site of action: group 2 (see pages 14-15).
в– в– May be mixed with 2,4-D, dicamba, Buctril, or MCPA to improve control of Canada thistle, giant ragweed, lambsquarters and other broadleaf weeds. Follow restrictions on all labels with regard to growth stage and adjuvants
in mixtures.
в– в– Apply in fall or spring after crop emergence and before the second node is detectable in stem elongation
(Feeke’s Growth Stage 7). Weeds should be 1 to 3 inches tall and actively growing for best results.
в– в– COC (1 to 4 pints/A) is the preferred adjuvant when Peak is applied alone using water as the carrier. Apply with
NIS (1 to 2 quarts per 100 gallons of spray) if fluid fertilizer is used as the spray carrier, or if mixing with any other
herbicide.
в– в– Apply in a spray volume of at least 10 gpa. Increasing the spray volume may improve control where the crop
and weed canopy is dense.
в– в– Do not apply when the crop is under stress due to drought, cold weather, or other factors, or if cold, wet conditions are expected within one week after application.
в– в– Allow 4 hours between application and rainfall.
в– в– Do not graze or feed treated crops to livestock until 30 days after application.
в– в– Crop rotation restrictions: soybeans - 10 months; forage grasses, alfalfa, clovers - 22 months.
Herbicide
Formulation
Product Rate Range
Starane
1.5L
1/2 - 2/3 pt
в– в– Starane (fluroxypyr) controls hemp dogbane, common ragweed and a few other broadleaf weeds. Due to a
relatively narrow spectrum of activity, Starane should generally be mixed with other herbicides to improve control of specific weeds.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply from the 2-leaf growth stage of wheat or oats up to and including flag leaf emergence, and when weeds
are less than 4 (1/2 pt/A) to 8 (2/3 pt/A) inches tall.
в– в– Do not plant soybeans within 4 months following Starane application.
Herbicide
Formulation
Product Rate Range
Stinger
3L
1/4 - 1/3 pt
в– в– Stinger (clopyralid) controls ragweeds, wild buckwheat, and Canada thistle, and suppresses sowthistle and
dandelion.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply from the 3-leaf stage up to early-boot stage of oat or wheat growth. Annual broadleaf weeds should have
no more than 5 leaves at the time of application.
в– в– For Canada thistle control, apply 1/3 pint when thistle plants are in the rosette (at least 4 inches tall or across) to
prebud stage.
Small Grains
Herbicide
Formulation
Product Rate Range
Sharpen
2.85SC
1 to 2 oz/A
в– в– Sharpen (saflufenacil) can be applied preplant or preemergence to wheat, oats, or barley. Sharpen controls
mareatail, and mixtures with glyphosate can provide more effective control of emerged weeds in no-till, compared with glyphosate alone. Sharpen provides residual control of marestail and other broadleaf weeds at rates
of 1.5 to 2 oz.
140
Small Grains: Oats and Wheat
Small Grains
в– в– Can be mixed with most other wheat herbicides for improved control of broadleaf weeds. See label for more information.
в– в– Do not harvest hay from treated fields.
в– в– Crop rotation restrictions: grasses - anytime; alfalfa, soybeans - 10 1/2 months after application; clovers - 18 months.
Herbicide
Formulation
Product Rate Range
Thifensulfuron + tribenuron methyl (active ingredients)
Harmony Extra TotalSol
50DF
Wheat 0.45 - 0.9 oz
Oats 0.45 - 0.6 oz
Nimble, Treaty Extra
75WDG
Wheat 0.3 - 0.6 oz
Oats 0.3 - 0.4 oz
Rapport BroadSpec
75DF
Wheat 0.4 - 1 oz
Rapport Tank Mix
75DF
Wheat 0.6 - 1 oz
в– в– Controls wild garlic and annual broadleaf weeds, including common lambsquarters, mustard species, Pennsylvania
smartweed, field pennycress, shepherd’s purse, common chickweed, purple deadnettle, and henbit.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Does not control ragweeds. Can be mixed with bromoxynil, 2,4-D or MCPA for improved control of Canada thistle,
ragweeds, and some other weeds. Ester formulations have provided better results than amines. Mixing with dicamba may result in reduced control of some broadleaf weeds.
в– в– Apply in fall or spring after wheat is in the 2-leaf stage, but before the flag leaf is visible. Annual broadleaf weeds
should be past the cotyledon stage, actively growing, and less than 4 inches tall or across at the time of application.
в– в– Apply when spring oats are in at least the 3-leaf stage, and before jointing. Do not apply to oats more than once
per season. Do not use on Ogle, Premier, or Porter varieties. Rapport products are not labeled for use on oats.
в– в– To control wild garlic, apply higher rates when garlic plants are less than 12 inches tall with 2 to 4 inches of new
growth. Control will be better if applied during warm weather (60 F or more) to actively growing garlic plants.
в– в– To suppress Canada thistle, apply higher rates when all thistles have emerged, are actively growing, and are 4 to 8
inches tall with 2 to 6 inches of new growth. Application with 2,4-D will improve thistle control.
в– в– The following adjuvant recommednations pertain to all products listed except Rapport BroadSpec and Tank Mix see Rapport product labels for adjuvant recommendations. If water is the spray carrier, apply with 0.25 to 0.5% v/v
NIS (1 to 2 quarts per 100 gallons). If the spray solution contains consists of no more than 50% UAN (and the other
50% is water), apply with 0.06 to 0.25% v/v surfactant (1/2 to 2 pints per 100 gallons). If the spray solution consists
of more than 50% nitrogen fertilizer, consult dealer or Dupont representative before adding an adjuvant. Temporary
crop injury may occur when applied with surfactant, when fertilizer is used as the spray carrier. This injury is occasionally severe, and risk of severe injury may increase under saturated soil conditions.
в– в– May be applied with flat fan or low-volume flood nozzles. Minimum spray volume is dependent upon nozzle type
and size. See label for additional information.
в– в– Most other crops can be planted 45 days after application (60 days for Rapport BroadSpec).
в– в– Do not graze or feed forage or hay from treated areas to livestock.
Herbicide
Formulation
Product Rate Range
WideMatch
1.5L
1.0 - 1.3 pts
в– в– WideMatch is a premix of clopyralid (Stinger) plus fluroxypyr (Starane) for control of broadleaf weeds, including
hemp dogbane, ragweeds, Canada thistle, marestail, and cocklebur. WideMatch should be mixed with other wheat
herbicide(s) for control of most winter annual weeds.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply from the 3-leaf growth stage of wheat or oats up to and including flag leaf emergence, and before weeds are
4 inches tall.
в– в– For most effective Canada thistle control, apply after the majority of the basal leaves have emerged and before bud
stage.
141
Oats and Wheat — Underseeded With Legumes
Herbicide
Formulation
Product Rate Range
2,4-D Amine
4 lb/gal
1/4 - 1/2 pt
MCPA Amine
4 lb/gal
1/2 pt
в– в– Site of action: group 4 (see pages 14-15).
в– в– Use low pressure (30 psi or less), and apply before jointing, but after the small grain and weeds have formed a
canopy over the legumes. Do not apply 2,4-D until the grain is 8 inches tall.
в– в– Controls most annual broadleaf weeds.
в– в– For best results, apply when weeds are small and actively growing.
в– в– MCPA is less likely to injure the legumes than 2,4-D, but both will cause some injury and stand loss. Red and ladino
clovers are more tolerant than other legumes. Do not apply MCPA to vetch or sweet clover. Do not apply 2,4-D to
sweet clover or alfalfa unless the weed infestation is severe and crop injury can be tolerated.
в– в– To minimize injury, do not use more than 6 gallons of water per acre when applying MCPA amine.
в– в– Do not forage or graze for 7 days (MCPA) or 14 days (2,4-D) after treatment.
Small Grains
Herbicide
Formulation
Product Rate Range
Bromoxynil
2S
1 - 1ВЅ pt
в– в– Can be applied to wheat, oats, barley, rye, and triticale underseeded with alfalfa only.
в– в– Site of action: group 6 (see pages 14-15).
в– в– Apply to small grains from emergence up to boot stage and when seedling alfalfa has 2 to 4 trifoliate leaves.
в– в– Apply when weeds have less than 4 leaves or are less than 2 inches tall, or before rosettes are 1 inch in diameter.
в– в– Apply in a minimum spray volume of 20 gpa with a minimum pressure of 30 psi.
в– в– Some crop leaf burn can result from application, especially under warm, humid conditions. Do not apply when temperatures will exceed 70 F the day of and for 3 days following application. Do not apply when alfalfa is under stress
by moisture, temperature, insect, or disease. в– в– Do not graze or harvest for 30 days following treatment.
142
Wheat: Harvest Aid
Herbicide
Formulation
Product Rate Range
2,4-D Amine
Various
1.5 lbs ai/A
2,4-D Ester
0.5 - 1.0 lb ai/A
в– в– Various formulations of 2,4-D can be applied with aerial or ground equipment after wheat has reached the hard
dough stage.
в– в– Site of action: group 4 (see pages 14-15).
в– в– The Weedar 64 label advises that crop injury can occur, and spot treatment is recommended to minimize the extent
of injury.
в– в– Do not feed wheat straw to livestock if a harvest-aid treatment of 2,4-D has been applied.
в– в– Take precautions to reduce spray drift. Corn, soybeans and other sensitive crops are likely to be growing in areas
surrounding treated wheat fields. Amine formulations of 2,4-D have less potential than ester formulations to move
off-target through volatilization and injure other plants.
Small Grains
Herbicide
Formulation
Product Rate Range
Aim
2EC
1 - 2 oz
в– в– Aim (carfentrazone) can be applied prior to harvest of mature small grains for dessication of velvetleaf, morningglory, pigweeds, and other weeds. Apply at least 3 days before harvest.
в– в– Site of action: group 14 (see pages 14-15).
в– в– The total amount of Aim that can be applied to small grains in one season, including postemergence and harvest
aid treatments, cannot exceed 2 oz/A.
в– в– Use a spray volume that results in complete coverage of foliage. Apply with NIS (0.25% v/v) or a COC (1 to 2% v/v).
UAN or AMS may also be added.
Herbicide
Formulation
Product Rate Range
Dicamba + 2,4-D premix
3.87L
2 pints
в– в– This product is available from various manufacturers, and product names and rates vary.
в– в– Apply when wheat is in the hard dough stage and the green color has disappeared from the nodes of the wheat
stem. Apply at least 7 days before harvest.
в– в– Can be mixed with glyphosate products registered for this use.
в– в– Do not use treated wheat for seed unless a germination test is performed on the seed.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
0.75 lb acid/A
в– в– Glyphosate can be applied as a preharvest treatment in wheat to control annual and perennial weeds. Table 24
contains a list of currently available glyphosate products. See labels for specific information on preharvest application.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Apply after the hard dough stage when grain moisture is 30% or less, and at least 7 days prior to harvest.
в– в– Some glyphosate products can be mixed with 2,4-D (0.5 to 1.0 lb ai/A) to broaden the spectrum of control.
в– в– Apply with ground or aerial application equipment using a spray volume of 3 to 10 gpa.
в– в– Wheat grown for seed should not be treated with glyphosate as reduction of germination and vigor may occur.
в– в– Take precautions to reduce spray drift. Corn, soybeans and other sensitive crops are likely to be growing in areas
surrounding treated wheat fields.
143
Figure 1. Wheat Growth Stages and Herbicide Application
Small Grains
144
Forages
Managing Weeds in Legumes
Managing weeds in forages requires a different
approach than weed management in row crops. Over
95% of the weed control in a healthy forage crop comes
from the competition provided by the forage. However,
to maintain a relatively weed-free forage, proper fertilization, cutting management, insect control, the use of
disease-resistant varieties, and selective herbicide use
are necessary to keep the forage stand competitive.
If weeds become a problem, they can compete or
interfere for light, nutrients, water, and space, directly influencing yield and standability. Common chickweed infestations in alfalfa have been reported to reduce forage
stand by more than 30%. Common chickweed emerges
in the fall and winter, and spring develops a thick lush
mat by early spring that can compete with the first forage cutting. Once the chickweed dies in early summer,
summer annual weeds such as foxtails, lambsquarters,
and pigweed or perennial weeds such as dandelion
can replace the dead or dying winter annual weeds and
continue to reduce forage yield and quality.
Unlike most grain or fiber crops from which weeds
are separated at harvest, weeds are often harvested
along with the forage crop, potentially reducing quality.
Reductions in quality are often in the form of lower protein content and feed digestibility. Although weeds do
have some feed value, this value differs among species.
Dandelions come close to equaling alfalfa in protein and
total digestible nutrients (TDN). Control of dandelion
may not necessarily improve the quality of hay, but it
may be of some value in reducing the time necessary
to dry the hay, since dandelion dries more slowly than
alfalfa. Increased drying time may mean greater harvest
losses due to untimely rainfall. Some weeds are toxic to
livestock, while others become toxic under certain environmental conditions. For information regarding plants
that are toxic to live stock see the following web sites:
http://www.vet.purdue.edu/depts/addl/toxic/cover1.htm
or http://www.ansci.cornell.edu/plants/index.html.
Grassy weed quality can be similar to that of the
forage. In general, weedy grasses have about 75% of
the quality of alfalfa. However, controlling quackgrass
in alfalfa can increase forage protein levels 4% to 7%.
Weeds with woody stems or flower stalks, such as yellow rocket, white cockle, rough fleabane, curly dock,
and broadleaved dock, have lower protein levels (about
50% of the quality of alfalfa), so controlling them is even
more important.
When weeds are present or persist in spite of good
management, herbicides can help improve yield and
quality. Weed control at establishment or in the seedling year is most critical for maintaining a healthy forage
stand. When weeds are controlled the seedling year, the
forage crop seldom requires additional herbicide treatments for at least the first two years of the stand.
Weed management in forages can be divided into
two phases: control in the establishment or seedling
year and control in an established stand.
Control before and during
establishment
Managing weeds in forages begins long before crop
establishment. Certain types of weeds are potentially serious problems for forages, so it is important to eliminate
them in advance. In particular, perennial broadleafs and
grasses such as dandelion, curly dock, Canada thistle,
and quackgrass are much easier to manage prior to
planting a forage crop. In addition, biennial weeds such
as musk thistle, wild carrot, and burdock should be eliminated before establishing forage. If these weeds are not
removed before the seeding is made, they commonly
persist throughout the life of the forage. The cost of controlling weeds before or at the time of seeding should
be considered an investment that will be returned for
the life of the stand.
Below are some general rules for managing weeds at
establishment or in the seedling year:
1. Weeds that emerge with the crop are generally more
destructive.
2. Maintain the forage relatively weed-free for the first
60 days.
3. Weeds that emerge beyond 60 days will not influence that year’s forage yield.
4. Later-emerging weeds may still influence forage quality.
5. Winter annual weed competition in early spring is
most damaging to forages.
6. Broadleaved weeds are generally more competitive
against legumes than grassy weeds.
Herbicides are needed most often during establishment, and several options exist for managing weeds in
pure legume seedings. In no-till seedings, adequately
controlling the existing vegetation prior to planting is
very important, especially perennials. Weed control is
also very important while the forage is young and prone
to competition from invading species.
145
Control in established alfalfa
The best weed control in an established forage
stand is achieved by maintaining a dense healthy stand
through proper fertilization, cutting management, and
insect control. Controlling weeds in established forages
is normally of greatest benefit in the first cutting. Weeds
generally cause less yield loss in the second and succeeding harvests. Before using a herbicide in established stands, evaluate the forage to ensure it is worth
the cost of the herbicide.
Below are some general rules to follow before using
a herbicide in established forage stands:
1. Thin or irregular stands will not thicken once weeds
are removed. Be sure there are sufficient desirable
species to fill in the gaps. Use the following guidelines to evaluate stands.
Stems per square foot
Effect on Yield
55 Stem density not limiting yield
40-55
Some yield reduction expected
<40 Significant yield reduction
YearMinimum number of plants/square foot
Fall of seeding year 25-30
2nd10-15
3rd or older 5-6
2. Weeds tolerant of the herbicide may invade the
space left by susceptible species, ultimately creating
a more severe weed problem.
3. Only well-established vigorous stands should be
treated with herbicides.
4. If the forage stand is at least two years old and 25%
to 30% are weeds, removing them with an herbicide
application is of questionable value.
5. If 50% or greater of the stand are weeds, it is time to
rotate to a different crop.
6. Weed control in established stands is most effective
when herbicides are applied in the fall or early spring.
Application of metribuzin or Velpar in winter when
established alfalfa is dormant is the most efп»їfective
method of broadleaf weed control.
If weeds become a problem in established forages,
several herbicide options are available. Chemical control
in established forage legumes is often limited to late fall
or early spring applications. Also, many products have
harvesting, feeding, or grazing restrictions following
their use.
Adapted with modifications from the Penn State Field
Crop Pest Management/Agronomy Guide.
Forages
146
Table 20. Weed Response to Herbicides in Alfalfa
This table compares the tolerance of forages to herbicides and the relative effectiveness of herbicides on weeds. Ratings are
based on labeled application rate and weed size or growth stage. Performance may vary due to weather and soil conditions or
other variables.
Forage crop tolerance rating:
  0 = Excellent Tolerance; 1 = Good Tolerance; 2 = Fair Tolerance; 3 or greater = Poor Tolerance; and N = No Information.
Weed control rating:
  9 = 90% to 100%; 8 = 80% to 90%; 7 = 70% to 80%; 6 = 60% to70%; - = less than 60% control, not recommended.
BFT
Barnyardgrass
Crabgrass
Downy Brome
Fall Panicum
Foxtails
Orchardgrass
Quackgrass
Volunteer Grain
Yellow Nutsedge
Canada Thistle
Chickweed
Dandelion
Dock, Curly
Field Pennycress
Henbit
Lambsquarters
Mustard, Wild
Nightshade
Pigweed
Plantain
Ragweed, Common
Ragweed, Giant
Shepherd's purse
Smartweed
Wild Radish
Yellow Rocket
Broadleaf Weeds
Red Clover
Balan
Eptam
Aim
Bromoxynil
Butyrac
Chateau
Clethodim
Extreme1
Glyphosate1
Kerb
Metribuzin
Paraquat
Poast/Poast
Plus
Prowl H2O
Pursuit
Raptor
Sinbar
Velpar/Velossa
Grasses
Alfalfa
Forages
Forage Crop
Tolerance
1
1
1
2
1
1
0
1
6
1
1
1
0
1
1
1
N
1
0
N
9
1
N
N
0
1
1
N
1
0
N
9
1
N
N
0
9 9 9
9 9 9
- - - - - - - - 9 8+ 9
9 9 9
9 9 9
8 8 9
6 5 9
8 7 9
9 9 9
9
9
9
9
9
6
6
9
9
6
6
8
8
7
6
8
9
9
9
8
7
8
8
8
8
9
9
6
8
8
7
7
-
6
9
9
-
8
8
8
7
-
-
6
7
8
9
8
-
9
6
8
6
9
-
9
9
7
9
8
9
-
6
6
8
9
9
-
8
8
9
9
-
9
9
8
8
8
9
-
-
6
9
9
7
-
8
9
-
7
6
9
9
9
-
9
6
7
-
-
7
7
8
-
8
6
-
9
9
9
-
9
8
9
9
-
9
6
9
8
-
9
9
9
-
9
6
9
-
9
6
9
9
-
9
8
-
9
8
9
-
9
9
-
9
9
9
-
9
9
9
-
8
5
8
-
9
9
8
-
1
1
2
1
1
N
N
N
N
N
N
N
N
N
N
8
6
6
6
7
9 8 7 8 7 8+ 6 7 6 7 6
-
-
-
- 6- 6 8 6 8 - 9 6
- 9 8
6
6
- 8+ 8
8 8 6
8 8 8
9 9 9
9 8 9
9
9
9
9
9
9
6
6
9
9
9
8
9
7
8
6
7
8
8
7
8
-
6
9
9
9
9
6
9
8
8
8
9
9
9
7
8
8
7
9
9
7
7
7
7
7
9
8
9
9
9
9
9
8
6
9
9
8
7
6
6
9
9
9
8
9
8
-
1Use in Roundup Ready alfalfa only, unless loss of stand is acceptable where spot treating with glyphosate.
147
Forage Legumes
Herbicide
Formulation
Product Rate Range
Aim
2EC
0.5 - 2.5 oz
в– в– Aim (carfentrazone) is a contact herbicide that controls or suppresses several small annual broadleaf weeds in
established stands of alfalfa, clover, and other legumes. Aim is labeled for use in legume stands that do not contain
grasses.
в– в– Apply in winter when legumes are dormant or between cuttings during the growing season. In-season applications
should be made as soon as possible after hay removal, and prior to significant regrowth of stems and crowns (up to
6 inches of new growth).
в– в– Apply with NIS (0.25% v/v), or with COC (0.5 - 1% v/v) for increased activity. Weeds should be less than 4 inches tall,
and rosettes less than 3 inches across at time of application.
в– в– Temporary leaf speckling and necrosis may occur with in-season treatments, and this is enhanced by use of COC
and the presence of moisture on foliage.
Herbicide
Formulation
Product Rate Range
Butyrac 200 (2,4-DB)
2L
1 - 3 qt
в– в– Site of action: group 4 (see pages 14-15).
в– в– Controls annual broadleaf weeds in seedling forage legumes (alfalfa, clovers, and birdsfoot trefoil) and established
alfalfa. Do not use on sweet clover.
в– в– Apply in spring or fall when legumes have 2 to 4 trifoliate leaves. Annual weed seedlings should be no more than 2
to 3 inches tall. Rosettes should be no more than 2 inches across and not bolting. Weeds that emerge in the fall and
overwinter in the rosette stage (mustards, field pennycress) may be more easily controlled in late fall than in spring.
в– в– Apply 1 to 2 quarts/A when weeds are less than 1 inch tall, and 2 to 3 quarts when weeds are 1 to 3 inches tall. Use
the 3-quart rate for smartweed or curly dock.
в– в– Do not harvest or graze for 60 days following treatment.
в– в– Butyrac 200 can be mixed with Poast Plus for control of a mixed population of grass and broadleaf weeds in alfalfa.
Herbicide
Formulation
Product Rate Range
Chateau
51 WDG
up to 4 oz
в– в– Chateau (flumioxazin) provides residual control of annual broadleaf weeds in established alfalfa. Does not control
emerged weeds.
в– в– Apply when alfalfa has 6 inches of growth or less.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Do not harvest or graze for 25 days after application.
в– в– Do not apply with adjuvants or mix with products formulated as emusifiable concentrates (EC), unless applying after
the last alfalfa cutting for the year.
Forages
Herbicide
Formulation
Product Rate Range
Bromoxynil
2S
1 - 1ВЅ pt
в– в– Site of action: group 6 (see pages 14-15).
в– в– Apply in the fall or spring to seedling alfalfa with 4 trifoliate leaves when weeds have less than 4 leaves or are less
than 2 inches tall, or before rosettes are 1 inch in diameter. Do not apply to established alfalfa
в– в– Apply in a minimum spray volume of 20 gpa with a minimum spray pressure of 30 psi.
в– в– For improved control of pigweed, mix 1 pint of bromoxynil with 1 quart of Butyrac 200.
в– в– Crop leaf burn often occurs from bromoxynil application and is increased by warm, humid conditions. To avoid serious crop injury, do not treat when temperatures will exceed 70 F on the day of and for 3 days following application.
Injury can be more severe in mixtures with Butyrac 200.
в– в– Do not apply when alfalfa is under stress from moisture, temperature, insects, or disease.
в– в– Do not graze or harvest for 30 days following treatment.
148
Forage Legumes
Herbicide
Formulation
Product Rate Range
Clethodim
Various
See labels
в– в– Clethodim controls annual and perennial grasses in alfalfa. Clethodim is sold under various trade names, including
Select, Arrow, Section, and Select Max.
в– в– Site of action: group 1 (see pages 14-15).
в– в– Most clethodim products are 2 lb/gal formulations, and should be applied at a rate of 6 to 8 ounces per acre for control of annual grasses up to 8 inches tall. Perennial grasses will generally require higher rates and may require more
than one application. Application should be delayed until perennial weeds are at least 4 to 12 inches tall for best
results. These products should generally be applied with COC (1% v/v) for best results. UAN or AMS can be added.
в– в– Select Max should be applied at a rate of 9 to 12 oz/A for annual grasses less than 6 inches tall, and 12 to 32 oz/A
for larger annual grasses or perennial grasses. Apply with NIS (1 qt/100 gallons) plus AMS (2.5 to 4 lbs/A). COC or
MSO can be used instead of surfactant under hot,dry conditions.
в– в– Clethodim can be mixed with other herbicides for control of a mixed population of grass and broadleaf weeds. See
labels for more information.
в– в– Allow 15 days between application and grazing, feeding, or harvesting of alfalfa.
в– в– Allow 1 hour between application and rainfall.
Forages
Herbicide
Formulation
Product Rate Range
Eptam
7E
3 1/2 - 4 1/2 pt
10G
30 lb
Balan
1.5EC
3 - 4 qt
в– в– Site of action: group 3 (Balan), group 8 (Eptam). See pages 14-15.
в– в– Control annual grasses and some broadleaf weeds in alfalfa, clovers, and birdsfoot trefoil. High rates of Eptam provide some control of yellow nutsedge and quackgrass.
в– в– Apply to prepared seedbed shortly before seeding, and incorporate 2 to 3 inches deep immediately following application.
в– в– Do not use when a companion crop of grain or forage grass is in the seeding mixture.
в– в– Do not use Eptam on white Dutch clover.
в– в– Do not use Balan on soils high in organic matter.
Herbicide
Formulation
Product Rate Range
Gramoxone SL
2L
1 pt (between cuttings)
1 - 2 pts (seedling - dormant)
2 - 3 pts (established - dormant)
Parazone
3SL
0.7 pt (between cuttings)
0.7 to 1.3 pts (seedling - dormant)
1.3 - 2 pts (established - dormant)
в– в– Paraquat is the active ingredient in these products.
в– в– Site of action: group 22 (see pages 14-15).
в– в– Controls or suppresses small emerged grass and broadleaf weeds in dormant stands or between cuttings. Weeds
beyond the seedling stage may not be controlled. Paraquat provides effective control of henbit, but control of common chickweed is variable.
в– в– Apply with NIS (0.125 to 0.25% v/v) in a minimum spray volume of at least 10 gpa. Increase spray volume to 15 to 20
gpa where foliage is dense.
в– в– When using between cuttings, apply no later than 5 days after alfalfa has been removed. Injury to first-year alfalfa will
be more severe than to established stands. Stand and yield may be reduced if alfalfa is allowed to regrow more than
2 inches between cutting and application. Do not make more than 2 applications during the first growing season.
149
Forage Legumes
в– в– When using on dormant alfalfa, apply during winter or early spring before alfalfa starts new growth. Early-spring
application is usually most effective. Do not cut or harvest within 42 days after application. Do not apply more than
once during the first growing season.
Herbicide
Formulation
Product Rate Range
Kerb
50W
1 - 3 lb
в– в– Site of action: group 3 (see pages 14-15).
в– в– Apply in the fall after the soil temperature is below 60F and until the ground freezes. Alfalfa plants must have
reached the first trifoliate leaf stage. Can be applied to seedling alfalfa and established stands of alfalfa, clover,
birdsfoot trefoil, and crown vetch, as long as there are no desirable grasses.
в– в– Controls many perennial grasses, volunteer grains, downy brome, and chickweed.
в– в– Use 1 to 1ВЅ pounds per acre to control volunteer grains, downy brome, and chickweed, and 2 to 3 pounds to control quackgrass.
в– в– Do not graze or harvest for 120 days following application.
Herbicide
Formulation
Product Rate Range
Poast
1.5E
12 - 24 oz
Poast Plus
1E
18 - 36 oz
в– в– Poast (sethoxydim) and Poast Plus (sethoxydim plus Dash) control annual and perennial grasses in alfalfa and clover.
Herbicide
Formulation
Product Rate Range
Prowl H2O/Satellite Hydrocap
3.8 CS
New stands: 1.1 - 2.1 pts
Established: 1.1 to 4.2 qts
в– в– Site of action: group 3 (see pages 14-15).
в– в– Provides residual control of most annual grasses and certain broadleaf weeds.
Forages
в– в– Site of action: group 1 (see pages 14-15).
в– в– Apply with Dash (1 pint/A) or COC (2 pints/A). For best control of crabgrass, volunteer cereals, and quackgrass, also
include UAN (1/2 to 1 gallon/A) or AMS (2 1/2 lbs/A).
в– в– For control of volunteer wheat in summer seedings, apply 24 ounces /A of Poast or 36 ounces/A of Poast plus with
Dash or COC plus UAN or AMS. Apply in the fall before wheat is 4 inches tall and prior to tillering.
в– в– Apply in spray volume of 5 to 20 gpa with a pressure of 40 to 60 psi. Adjust spray pressure, spray volume, and
boom height to ensure penetration of canopy and coverage of grasses.
в– в– The rate is 16 oz/A of Poast or 24 oz/A of Poast Plus per acre for control of most annual grasses up to 8 inches tall.
The rate may be reduced for control of barnyardgrass, giant and green foxtails, and fall panicum that are up to 4
inches tall and actively growing.
в– в– Quackgrass and other perennial grasses require higher rates and often two applications. Apply 24 oz/A of Poast
or 36 oz/A of Poast Plus when quackgrass is 6 to 8 inches tall, and make a second application at 2/3 the initial rate
when regrowth reaches the same height.
в– в– Oats inter-seeded with alfalfa may be killed with a rate of 16 oz/A of Poast or 24 oz/A of Poast Plus before oats
exceed 10 inches in height.
в– в– Not recommended for control of cereals planted the previous fall.
в– в– May be mixed with Butyrac 200 for control of a mixed population of grass and broadleaf weeds. Apply this mixture
with COC only, and observe feeding, grazing, and harvesting restrictions for Butyrac.
в– в– Mixing Poast or Poast Plus with Pursuit often results in reduced grass control.
в– в– Allow 1 hour between application and rainfall.
в– в– Do not apply to grasses under stress from lack of moisture, herbicide injury, or low temperatures.
в– в– Do not feed, graze, or harvest forage for 7 days following application. Do not feed or harvest dry hay for 14 days following application.
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Forage Legumes
в– в– Seedling alfalfa: apply prior to weed emergence. Seedling alfalfa must be in at least the 2nd trifoliate stage of
growth but not more than 6 inches tall at the time of application.
в– в– Provides residual control of most annual grasses and certain broadleaf weeds.
в– в– Established alfalfa (mowed at least once): apply prior to weed emergence in the fall after last cutting, in the spring,
or between cuttings. Alfalfa should have less than 6 inches of regrowth at time of application.
в– в– Some stunting and chlorosis of alfalfa may occur with postemergence applications.
в– в– Apply rates less than 2.1 pts at least 28 days prior to harvest, and wait 50 days for higher rates.
Herbicide
Formulation
Product Rate Range
Pursuit
2S
3 - 6 oz
в– в– Pursuit (imazethapyr) is a translocated imidazolinone herbicide that controls annual broadleaf weeds and controls
or suppresses grasses. Control of ragweeds and lambsquarters is variable. Does not control ALS-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
Forages
в– в– Can be applied postemergence to seedling or established alfalfa. Apply in spring or fall when seedling alfalfa is in
the 2nd trifoliate stage or larger. For established alfalfa, Pursuit can be applied in the fall after the last cutting, in the
spring before or after alfalfa breaks dormancy, or between cuttings. Apply spring treatments before alfalfa growth
exceeds 3 inches to allow adequate spray coverage on weeds.
в– в– Pursuit application may cause a temporary yellowing or reduction in alfalfa height.
в– в– Apply in a spray volume of at least 10 gpa with NIS (1 qt/100 gallons) or COC (1ВЅ to 2 pints/A) plus UAN (1 to 2
quarts/A) or spray grade AMS (2 1/2 lbs/A). Control of large or drought-stressed weeds will be maximized when the
higher rates of fertilizer are used in combination with a seed-oil based COC (Meth Oil, Priority MSO, or Sun-It II, for
example).
в– в– Can be mixed with Buctril/Moxy, 2,4-DB, or Poast Plus to control additional weeds. Control of some grasses may be
reduced when mixed with Poast Plus.
в– в– Apply when annual weeds are 1 to 3 inches tall. For low growing weeds such as mustards, apply before the rosette
exceeds 3 inches in diameter.
в– в– If replanting is necessary in a field treated with Pursuit, do not replant to alfalfa for 4 months following application.
See label for other recrop restrictions.
Herbicide
Formulation
Product Rate Range
Raptor
1AS
4 - 6 oz
в– в– Raptor (imazamox) is a translocated imidazolinone herbicide that controls annual broadleaf and grass weeds. Raptor generally provides better control of lambsquarters and annual grasses than Pursuit. Control of common and giant ragweeds and waterhemp is variable. Raptor provides a shorter period of residual control compared to Pursuit.
Does not control ALS-resistant weeds.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Seedling year: apply when alfalfa is in the 2nd trifoliate stage or larger, and when weeds are 1 to 3 inches tall or
when rosettes are 1 to 3 inches wide.
в– в– In established stands, Raptor can be applied: 1) in early spring when alfalfa is dormant and winter annual weeds
are emerging; 2) before the first cutting; 3) between cuttings; or 4) in the fall after the last cutting. Apply before
alfalfa growth exceeds 3 inches to allow adequate spray coverage on weeds. Weeds should be no more than 1 to 3
inches tall or 1 to 3 inches wide (for rosettes) at the time of application.
в– в– Raptor application may cause a temporary yellowing or reduction in alfalfa height.
в– в– Raptor should be applied with NIS (1 to 2 quarts/100 gallons spray) or a COC (1 to 2 gallons/100 gallons) plus UAN
(2.5 gallons/100 gallons) or AMS (12 to 15 pounds/100 gallons). AMS is generally the preferred nitrogen source over
UAN or 10-34-0. Control of large or drought- or temperature-stressed weeds will be maximized when the higher
rates of fertilizer are used in combination with a seed oil-based COC (Meth Oil or Sun-It II, for example).
в– в– Apply in a spray volume of 10 to 20 gpa with a pressure of 20 to 40 psi. Flat fan spray nozzles are recommended
for adequate plant coverage. Allow 1 hour between application and rainfall.
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Forage Legumes
в– в– Control may be reduced when weeds are growing slowly under cold or dry conditions. If possible, wait for rain and
resumption of active weed growth before applying Raptor. If air temperatures reach or stay below 50 F for 10 or
more hours, delay application for 48 hours from the time temperatures increase above 50 F.
в– в– Can be mixed with one or more of the following: bromoxynil, Poast/Poast Plus, clethodim, or 2,4-DB.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
2% v/v solution
в– в– Table 24 contains a list of currently available glyphosate products. See labels for more information on this type of
application.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Apply as a spot treatment in established stands to control problem weeds that cannot be controlled by any other
means.
в– в– Apply to actively growing, susceptible weeds.
в– в– To avoid crop injury, avoid contact with desirable, nontarget vegetation (forage).
в– в– For maximum effectiveness on target vegetation, refer to label for recommended timing of application.
в– в– Treat no more than 1/10 of an acre at one time. Further applications may be made to the same area at 30-day intervals.
в– в– Do not graze or harvest for 14 days following application.
Herbicide
Formulation
Product Rate Range
Metribuzin (Tricor, Glory)
4F
1/2 - 2 pt
75DF
1/3 - 1 1/3 lb
в– в– Site of action: group 5 (see pages 14-15).
в– в– Use in established alfalfa only. Apply once in the fall or spring to dormant alfalfa (before new growth starts).
в– в– Application rate varies with target weed, and soil texture and organic matter content.
в– в– Controls downy brome and most winter annual weeds, including chickweed, henbit, mustards, and yellow rocket.
High rates will suppress dandelion, curly dock, and quackgrass. The 1/3 lb/A rate is for control of chickweed only.
в– в– Do not use on sandy soils or soils with pH greater than 7.5.
в– в– Do not graze or harvest for 28 days following application.
Herbicide
Formulation
Product Rate Range
Treflan/Trifluralin
TR-10/10G
20 lb
в– в– Site of action: group 3 (see pages 14-15).
в– в– Controls annual grasses in established alfalfa.
в– в– Apply in the spring before weed emergence.
в– в– A single rainfall or overhead irrigation of 1/2 inches or more within 3 days of application is required for this treatment to be effective.
в– в– The year following Treflan application, plant only crops for which Treflan may be applied as a preplant incorporated
treatment or injury may result.
Forages
Herbicide
Formulation
Product Rate Range
Sinbar
80W
1/2 - 1ВЅ lb
в– в– Site of action: group 5 (see pages 14-15).
в– в– Use in established alfalfa only. Apply once in the fall or spring to dormant alfalfa (before new growth starts).
в– в– Application rate varies with soil type. Use lower rates for coarser soils. Do not use on soils with less than 1 percent
organic matter.
в– в– Do not apply to snow-covered or frozen ground.
в– в– Controls chickweed, henbit, mustards, and yellow rocket. Suppresses dandelion and quackgrass.
в– в– Do not plant any other crop for 2 years after Sinbar application.
152
Forage Legumes
Herbicide
Formulation
Product Rate Range
Velpar/Velossa
2L
1 - 3 qt
в– в– Site of action: group 5 (see pages 14-15).
в– в– Use in established alfalfa only. Apply in the fall or spring when alfalfa is dormant or before new growth exceeds 2
inches in height. Can also be applied to stubble after hay crop removal, but before regrowth exceeds 2 inches.
в– в– Application rate varies with soil type.
в– в– For best results, apply when weeds are less than 2 inches tall and rosettes are less than 2 inches across.
в– в– Controls most winter annual broadleaf weeds, including chickweed, mustards, and yellow rocket. Controls dandelion and downy brome.
в– в– Do not plant any crop except corn within 2 years of treatment. Corn may be planted 12 months after treatment
where deep tillage is used.
в– в– Do not graze or harvest for 30 days following treatment.
Alfalfa: Preharvest Glyphosate Application
Forages
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
See labels
в– в– Some glyphosate products can be used in declining alfalfa stands where crop destruction is desirable or acceptable. Table 24 contains a list of currently available glyphosate products.
в– в– Site of action: group 9 (see pages 14-15).
в– в– A preharvest application will control annual and perennial weeds, and greatly improve control of alfalfa and perennial grasses compared to application after harvest.
в– в– Apply in a spray volume of 3 to 10 gpa just prior to alfalfa harvest in spring or fall.
в– в– Allow a minimum of 36 hours between application and harvest. Optimum harvest time is 3 to 7 days after application to maintain hay quality and maximize perennial control.
в– в– The treated alfalfa can be fed to any livestock including lactating animals.
в– в– If the field is planted to corn following alfalfa harvest, including atrazine in the preplant/preemergence herbicide
program will aid in control of perennial grasses. Postemergence application of dicamba or dicamba + 2,4-D may be
required for complete control of alfalfa in the corn.
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Mixed Grass-Legume Forages: Established Stands Only
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
2% solution (spot treatment)
в– в– Table 24 contains a list of currently available glyphosate products. See labels for more information on this type of
application.
в– в– Apply as a spot treatment to problem weeds not controlled by any other means.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Apply to actively growing, susceptible weeds.
в– в– To avoid crop injury, avoid contact with desirable, nontarget vegetation (forage).
в– в– For maximum effectiveness on target vegetation, refer to label for recommended adjuvants and timing of application.
в– в– Treat no more than 1/10 of an acre at one time. Further applications may be made to the same area at 30-day intervals.
в– в– Do not graze or harvest for 14 days following application.
Herbicide
Formulation
Product Rate Range
Metribuzin
4F
3/4 - 1ВЅ pt
75DF
1/2 - 1 lb
в– в– Can be used in alfalfa-grass mixtures.
в– в– Apply once in the fall or spring when plants are dormant (before new growth starts).
в– в– Site of action: group 5 (see pages 14-15).
в– в– Application rate varies with soil texture and organic matter content.
в– в– Higher rates may injure grass component.
в– в– Do not use on sandy soils or soils with pH greater than 7.5.
в– в– Do not graze or harvest for 28 days following application.
Forages
154
Roundup Ready Alfalfa
Forages
Herbicide
Formulation
Product Rate Range
Extreme
2.17L
2.2 to 4.4 pts
в– в– Extreme is a premix of imazethapyr (Pursuit) and glyphosate for postemergence control of annual and perennial
weeds in seedling or established Roundup Ready alfalfa. Pursuit provides residual control of some grass and
broadleaf weeds also. See Pursuit and glyphosate descriptions for additional information.
в– в– Site of action: group 2 (imazethapyr); group 9 (glyphosate). See pages 14-15.
в– в– Extreme can be applied to seedling alfalfa that is in the second trifoliate stage or larger. For low-growing weeds,
apply before the rosette exceeds 3 inches in diameter. New seedings of Roundup Ready alfalfa should be treated
with glyphosate or Extreme at or before the 3 to 4 trifoliate stage, to eliminate the seedlings that may not be resistant to glyphosate.
в– в– Extreme can be applied to established Roundup Ready alfalfa in the fall, in the spring to dormant or semi-dormant
alfalfa (less than 3 inches of new growth), or between cuttings.
в– в– Avoid application during periods of unusually cool weather (temperatures less than 50 degrees). Allow one hour
between application and rain.
в– в– Allow at least 30 days after application before grazing, cutting, or feeding of Roundup Ready alfalfa forage or hay.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
0.75 lb acid/A (new seedings)
0.75 to 1.5 lb acid/A (established)
в– в– Glyphosate can be applied to established stands of Roundup Ready alfalfa for control of annual and perennial
weeds. Not all glyphosate products are approved for this use – see labels for more information.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Glyphosate should be applied after weeds have emerged but before alfalfa growth or regrowth interferes with
spray coverage on weeds. New seedings of Roundup Ready alfalfa should be treated with glyphosate or Extreme
at or before the 3 to 4 trifoliate stage, to eliminate the seedlings that may not be resistant to glyphosate.
в– в– Application when annual weeds are less than 6 inches tall will result in most effective control and allow use of lower
rates. Perennial weeds should be larger for most effective control. Application in the late fall may be the most
effective strategy on cool-season perennials such as dandelion and Canada thistle, when there is adequate time
after the last cutting for considerable regrowth of weeds. Multiple applications may be necessary to control some
perennials.
в– в– The rate of glyphosate in any single application should not exceed 1.5 lbs a.e./A. Sequential applications should be
at least 7 days apart. The combined total per year for all in-crop applications should not exceed 4.5 lbs a.e./A.
в– в– Remove livestock before application and wait a minimum of 5 days after last application before grazing, cutting, or
feeding of Roundup Ready alfalfa forage or hay.
155
Management Strategies for Permanent Grass
Pastures/CRP/Grass Hay
enough leaf area can be removed to affect the plant
growth. Elongation of the stem and development of a
large plant occurs in the second year, as well as flowering and seed production. Mowing can be used in year
two to control biennial plant growth and reduce seed
production. Perennial weeds reproduce by both seed
and plant parts such as stems, tubers and roots. Perennials should be mowed in the early bud stage. This is
the point in the life cycle when carbohydrate movement
from roots is at the lowest levels. Mowing at this time
can help reduce the viability of the plant parts used to
produce new plants and prevent seed production, but
mowing rarely controls perennials completely. The bottom line - mowing can be used to prevent seed production, and it can effective for weed control when used at
plant growth stages when the plant is most vulnerable
or least likely to regrow.
A combination of mowing and herbicide applications may be most effective for the control of perennial
weeds. Mowing in mid-summer removes weed growth
from the first half of the season, and prevents seed
production by many annuals and biennials. The initial
growth of cool-season perennials is also removed, followed by their regrowth into the fall, when herbicides
can be most effective. Mowing CRP areas before the
first week of August will allow for maximum regrowth of
perennial weeds. Applying herbicide in July or August
will prevent seed production by annual weeds, but this
is not the most effective timing for control of cool-season perennial weeds.
The most effective herbicide application timing for
perennial weed control is generally mid-September
through late October depending upon the species.
Herbicide effectiveness at that time will be maximized
by applying after several days of warm weather when
perennial weeds are fairly large and/or in the bud to
flower stage. Perennial weeds should be at least 8 to
12 inches tall in order to obtain maximum control of the
roots or rhizomes for next year. For warm-season perennials such as johnsongrass, hemp dogbane, milkweeds,
common pokeweed, and bindweeds, applications in
mid- to late September should provide the most effective control. This strategy can prove effective in controlling perennial weeds, which are not well controlled by
mowing alone.
Herbicides can effectively control many weeds in
pastures and CRP, and can be a less expensive alternative to mowing. Herbicide effectiveness, similar to
Grass Pastures
Long-term management of weeds in pasture and
CRP areas is necessary to maximize pasture productivity
and the growth of desirable species established in CRP
areas, control weeds that are poisonous to livestock,
and to prevent the encroachment of weeds into adjacent crop production fields. Some weed species are
considered noxious weeds under state law and must be
controlled, or the landowner can be subject to fines.
Many forage and grass species used in pastures and
CRP have prolific growth characteristics and are effective at suppressing weeds. Effective establishment
and maintenance of these species can greatly minimize weed problems. Factors in establishment include
starting weed-free through tillage or the application of
glyphosate or other non-selective herbicides, fertilization or liming as necessary based on soil testing, use
of the proper seeding rate, and proper maintenance of
over-grazed areas. Soil fertility should be periodically
monitored and supplemented to maintain a healthy
pasture or cover crop that is competitive with weeds.
This should include testing the nitrogen level for grass
species and pH for legume growth. Where phosphorous and potassium are at proper levels initially, these
nutrients should cycle through the residue unless hay
harvest is allowed. If the area is harvested for hay, then
soil in the area may need to be tested, and nutrients
applied to maintain further health of the pasture or CRP
cover. Use grazing practices that prevent deterioration of desirable species, since weeds will rapidly infest
areas devoid of a competitive stand of grasses and
legumes.
Weeds are controlled in pastures and CRP land primarily by mechanical or chemical methods. Mowing is
a viable option, depending upon the species to be controlled. Mowing is more effective for control when it can
be used several times in the same year. Custom rates
for rotary mowing in recent years averaged about $13
per acre, with a range of $6 to $19, based on information
from The Ohio State University and Purdue University.
Annual weeds should be mowed prior to or soon
after flowering to prevent the production of viable seed.
Seed production may occur earlier than the timing of
mowing allowed by CRP contracts. Biennial weeds have
a two-year cycle. Emergence of plants from seed occurs
in the first year, and the plants remain in the vegetative
stage as a low-growing rosette with short internodes
that grow close to the ground. Mowing is typically not
effective for control of plants in this stage, because not
156
mowing, also varies by weed life cycle and timing of
application. A primary disadvantage of herbicide application – most herbicides that can be used for control
of broadleaf weeds in CRP will injure or kill desirable
legumes in the cover. Exceptions to this are bromoxynil,
Butyrac, and Plateau, which can be applied to mixed
stands of grasses and legumes. These herbicides can
be used to control weeds during CRP cover establishment, depending upon the species planted and herbicide. Herbicide selection should take into account the
weed species, CRP cover species, application method,
and the presence of water in nearby ditches. Most herbicides can be applied to dry ditchbanks, but only some
dicamba, 2,4-D, and glyphosate products are labeled
for application directly to water. See product labels for
more information.
CRP contracts are written with maintenance provisions that include the control of weeds through mowing
or herbicides. The CRP contract usually limits mowing
to a certain time of the year, so as“not to disturb the
acreage under contract during the primary nesting and
brood rearing seasons for wildlife except as approved
by the CCC.” This limitation may reduce the overall
effectiveness of mowing as a weed control method,
especially for certain perennial species. CRP contracts
may allow more frequent mowing for control of noxious
weeds such as Canada thistle. Weed management
practices and the herbicides approved for use in CRP
can vary among states, and also within a state. Landowners should consult contracts and local NRCS offices
for more information on approved weed management
practices (see below). Labels for some products specify
application timing and rate based on the grasses that
are being established or are present in a CRP area. This
may include recommendations for cool-season vs warmseason grasses, which are categorized in the following
table. The tolerance of many native forbs and grasses
has not been characterized for some herbicides. Labels for some products warn of this and state that the
manufacturer is not responsible for injury to native forbs
and grasses.
See the following website for information on CRP
contract requirements and management practices:
http://www.nrcs.usda.gov/programs/crp/
Cool Season Grasses
Warm Season Grasses
Annual Ryegrass (I)1
Bluegrass, Rough (I)
Bahia (N)
Buffalo (N)
Bentgrass (I and N)
Canada wildrye (N)
Bermuda (I)
Eastern gramagrass (N)
Bluegrass, Kentucky (N)
Orchardgrass (I)
Big bluestem (N)
Foxtail millet (I)
Perennial ryegrass (I)
Smooth brome (N)
Bluestem yellow (caucasian) (I)
Indiangrass (N)
Tall fescue (I)
Timothy (I)
Little bluestem (N)
Pearl millet (I)
Broomsedge (N)
Swithgrass (N)
Virginia wildrye (N)
Grass Pastures
1I = introduced species, N = Native species. CRP guidelines require the use of native species.
157
Permanent Grass Pastures/CRP/Grass Hay
Herbicide
Formulation
Product Rate Range
2,4-D Amine
Various
1 - 2 lbs ai/A
2,4-D Ester
в– в– 2,4-D is labeled for use in grass pastures, CRP, and fallow land.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply 2 pints/A when annual weeds are small and actively growing. Rates of 1.5 to 2 lbs ai/A may be needed for
less susceptible annual weeds, and biennial and perennial weeds.
в– в– Spray bull or musk thistles or other biennial weeds in the rosette stage (spring or fall) while they are actively growing. Spray perennials such as Canada thistle in the bud to flower stage or in the fall regrowth stage. Spray susceptible woody species in the spring when leaves are fully expanded.
в– в– The ester formulation is more effective on wild garlic and onion than the amine formulation.
в– в– Do not graze dairy cattle for 7 days after treatment. Remove livestock from treated fields at least 3 days before
slaughter.
в– в– Do not apply to newly seeded areas or after heading begins. Do not apply to grass when it is in the boot to milk
stage if grass seed production is desired.
в– в– Will injure or kill desirable broadleaf plants in grass/forb mixtures. Do not reseed legumes or rotate to other crops
for 3 months or until chemical has disappeared from soil.
Herbicide
Formulation
Product Rate Range
Aim
2EC
0.5 - 2 oz
в– в– Aim (carfentrazone) is a contact herbicide that will control velvetleaf, pigweeds, lambsquarters, and a few other annual broadleaf weeds up to 4 inches tall in grass pastures. Aim will not control biennial or perennial weeds.
в– в– Site of action: group 14 (see pages 14-15).
в– в– Can be used in grass pastures, CRP areas, and grasses grown for hay or silage. There is no waiting interval between application of Aim and harvest or grazing.
в– в– Use a spray volume that results in complete coverage of foliage. Apply with NIS (0.25% v/v) or a COC (1 to 2% v/v).
UAN or AMS may also be added.
Herbicide
Formulation
Product Rate Range
Bromoxynil
2S
1 - 2 pt
в– в– Controls small winter and summer annual weeds in new CRP seedings. Can be applied during CRP cover establishment, after grasses have emerged. Bromoxynil can be applied to alfalfa, but will injure other legumes.
в– в– Apply when annual weeds have less than 4 leaves or are less than 2 inches tall, or before rosettes are 1 inch in
diameter.
в– в– Apply in a minimum spray volume of 20 gpa with a minimum spray pressure of 30 psi.
в– в– For improved control of pigweed, mix 1 pint of Buctril/Moxy with 1 quart of Butyrac 200.
Grass Pastures
Herbicide
Formulation
Product Rate Range
Butyrac 200 (2,4-DB)
2L
1 - 3 qt
в– в– Controls annual broadleaf weeds in CRP stands of grass, alfalfa, clovers, and/or birdsfoot trefoil. Do not use on
sweet clover. Can be used during establishment, but legumes should have emerged and grasses should be tillering or have a minimum of 6 leaves at the time of application.
в– в– Annual weed seedlings should be no more than 2 to 3 inches tall at the time of application, and rosettes should be
no more than 2 inches across and not bolting. Weeds that emerge in the fall and overwinter in the rosette stage
(mustards, field pennycress) may be more easily controlled in late fall than in spring.
в– в– Apply 1 to 2 quarts/A when weeds are less than 1 inch tall, and 2 to 3 quarts when weeds are 1 to 3 inches tall. Use
the 3-quart rate for suppression of smartweed or curly dock.
158
Permanent Grass Pastures/CRP/Grass Hay
Herbicide
Formulation
Product Rate Range
Chaparral
71.6 WDG
1.5 - 3.3 oz
в– в– Chaparral is labeled for use on grass pastures, established CRP areas, and natural areas.
в– в– Cimarron Max is a premix of metsulfuron methyl plus aminopyralid (Milestone). These are translocated herbicides
for control of primarily broadleaf weeds and brushy plants.
в– в– Site of action: group 2 (metsulfuron); group 4 (aminopyralid). See pages 14-15.
в– в– The standard rate is 2 oz/A when applied early-season for control of most pasture weeds. Increase rate if annuals
are more than 6 inches tall. Biennials should be treated as seedlings in the fall ideally, or in the spring/early summer when still small. Perennials should be treated prior to bloom.
в– в– For control of Canada thistle, apply 2 to 3.3 oz/A in fall before a killing frost, or in the spring after all plants have fully
emerged and up until the oldest plants are in flower stage.
в– в– Apply with COC/MSO (1% v/v) or NIS (0.25% v/v). AMS (2 lbs/A) or UAN (2 qts/A) can also be added.
в– в– Do not rotate to any other crop within one year following application. Do not use on soils with pH greater than 7.9.
Grass Pastures
в– в– Can be applied to many native and other grass species planted the previous season and fully tillered. Can be applied in spring or early summer to grass planted at least 4 months prior to application. If applied in the fall, do not
plant grasses the following spring.
в– в– Can cause stunting, yellowing, and seed head suppression on tall fescue. See label for precautions on this grass.
в– в– Animals grazing on treated pasture should be grazed on nontreated forage for 3 days before moving to areas
where sensitive broadleaf crops will be planted in the future. Manure in treated areas should be left on the pasture
or spread only on pasture grasses, wheat or corn. Do not use aminopyralid-treated plant residues, including hay
or straw from treated areas, or manure from animals that have grazed forage or eaten hay harvested from treated
areas within the previous 3 days, in compost or mulch that will be spread to areas where broadleaf plants may be
grown.
Herbicide
Formulation
Product Rate Range
Cimarron Max
co-pack
See labels.
в– в– Cimarron Max is labeled for use on grass pastures, established CRP areas, and warm and cool season native
grasses.
в– в– Cimarron Max is a co-pack of metsulfuron methyl plus a premix of dicamba and 2,4-D. These are translocated herbicides for control of broadleaf weeds and brushy plants.
в– в– Site of action: group 2 (metsulfuron); group 4 (2,4-D, dicamba). See pages 14-15.
в– в– Do not apply to timothy until 12 months after establishment. Lowest labeled rate should be applied to timothy in
late summer or fall.
в– в– Do not apply to bluegrass, bromegrass, or orchardgrass until 6 months after establishment, timothy until 12 months
after establishment, and fescue until 24 months after establishment. Lowest labeled rate should be applied late in
spring after 5 to 6 inches of new fescue growth, or in the fall.
в– в– On timothy and fescue, use NIS rather than crop oil to minimize injury. Do not use additional surfactants if UAN is
used as the spray carrier. Timothy should be at least 6 inches tall prior to application.
в– в– The metsulfuron component is a long-residual herbicide and is labeled with extensive restrictions on over-seeding
with legumes, pasture renovation, and crop rotation. Cautionary statements on the pasture label should be read
and understood by the user prior to use. See label for list of established CRP grasses that are tolerant to Cimarron
MAx.
в– в– Allow 4 hours between application and rainfall.
в– в– Do not graze lactating animals within 7 days of treatment. There is no waiting period for non-lactating animals, but
meat animals should be removed from treated areas 30 days prior to slaughter. Treated grasses may be harvested
for dry hay, but do not harvest within 37 days of treatment.
159
Permanent Grass Pastures/CRP/Grass Hay
Herbicide
Formulation
Product Rate Range
Crossbow/Crossroad/Candor
3L
Annuals - 1 - 2 qt
Biennials - 2 - 4 qt
Perennials - 2 - 4 qt
Woody brush - 6 qt
в– в– Crossbow/Crossroad is a premix of 2,4-D plus triclopyr for use in grass pastures and CRP. Can be used in cutstump, dormant stem, and basal applications.
в– в– Site of action: group 4 (see pages 14-15).
в– в– In CRP areas, apply only to established native grasses (not seedlings). Will injury or kill broadleaf forbs and legumes.
в– в– Apply to foliage during warm weather when brush and broadleaf weeds are actively growing. When applying as a
spot spray, thoroughly wet all foliage.
в– в– Be cautious of vapor and particle drift, as Crossbow may injure susceptible crops growing nearby.
в– в– Crossbow is effective for control of small ironweed and poison hemlock plants. For ironweed, apply 2 qt/A in early
summer before evidence of leaf rust is seen on the ironweed leaves. Apply when poison hemlock is small for best
results.
в– в– A foliar application of a 1ВЅ percent Crossbow solution applied in late April to early June has proven effective for
multiflora rose control. Dormant season (late winter to early spring) basal bark applications of a 4 to 5 percent solution will also control multiflora rose. See herbicide label for more specific rate recommendations.
в– в– Grazing restrictions for rates of 2 gallons per acre or less: Do not graze dairy animals for 14 days after treatment.
Other livestock: no waiting period between application and grazing, but remove animals from treated areas at least
3 days before slaughter.
Grass Pastures
Herbicide
Formulation
Product Rate Range
Curtail
2.38L
2 - 4 qt
в– в– Curtail is a premix of clopyralid (Stinger) plus 2,4-D for use on grass pastures and CRP areas.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Apply when annual weeds are small and actively growing. Treat bull or musk thistles in the spring or fall when they
are actively growing and in the rosette stage. Treat susceptible woody species in the spring when fully leafed out.
в– в– Apply in the fall for most effective CRP site preparation. Allow at least 30 days after application before seeding native grasses. Where CRP areas will be seeded in the fall, apply Curtail in spring or early summer. Do not exceed 4
qts/A in areas to be seeded.
в– в– Use higher rates for Canada thistle, and treat prior to the bud stage.
в– в– Do not treat pastures containing legumes unless injury can be tolerated. Established grasses are tolerant, but new
seedlings may be injured.
в– в– Do not graze lactating dairy cattle in treated areas for 14 days after application. Meat animals should be removed
from treated areas 7 days before slaughter (this is not necessary if at least 12 weeks have elapsed since application.
Do not cut treated grass for hay for 30 days after application.
в– в– Do not transfer livestock from treated grazing areas (or if fed treated hay) to sensitive broadleaf crops without first
allowing 7 days of grazing on an untreated pasture (or feeding untreated hay). If livestock are transferred within
less than 7 days of grazing untreated pasture or hay, urine or manure may contain enough clopyralid to injure sensitive broadleaf plants.
160
Permanent Grass Pastures/CRP/Grass Hay
Herbicide
Formulation
Product Rate Range
Dicamba
4L
Annuals - 1/4 - 1ВЅ pt
Biennials - 1/2 - 3 pt
Perennials - 1 - 6 qt
Woody brush - 1 - 8 qt
Distinct
76.4DF
Annuals - 4 - 8 oz
в– в– Dicamba is sold under various trade names, including Banvel, Clarity, Sterling, and Oracle. Dicamba is a translocated herbicide labeled for use in grass pastures and CRP.
в– в– Dicamba can be applied when seedling grasses are in at least the 3-leaf stage, and can be applied to established
grasses. Rates higher than 1 pt/A may severely injure seedling grasses. Dicamba will injure of kill desirable broadleaf plants in grass/forb mixtures.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Use lower rates for susceptible annuals when they are small and actively growing and for susceptible biennials in
the early rosette stage. Use higher rates for larger weeds, for less susceptible weeds, for established perennials in
dense stands, and for certain woody brush species.
в– в– Remove livestock from treated fields at least 30 days before slaughter. There is no waiting period between application and grazing for non-lactating animals. Do not graze lactating dairy animals for 7 to 60 days after application,
depending upon rate applied.
в– в– Allow 6 to 8 hours between application and rainfall.
в– в– Distinct is a premix of dicamba and diflufenzopyr that is more effective than the same rates of dicamba on many
weeds, especially Canada thistle and bindweeds. Apply with NIS or MSO, plus AMS.
в– в– Be cautious of spray drift and volatility.
Grass Pastures
Herbicide
Formulation
Product Rate Range
Dicamba + 2,4-D premix
3.87L
1 - 4 pts
в– в– This product is available from various manufacturers, and product names and rates vary. Controls broadleaf weeds
in pastures.
в– в– Site of action: group 4 (see pages 14-15).
в– в– When applied as a spot treatment, rates up to 8 pints/A can be used.
в– в– Apply with NIS (2 to 4 pts/100 gallons) using a spray volume of at least 5 gpa. Increase volume where in dense or
tall vegetation.
в– в– Allow 37 days between application and harvesting of grasses for hay or silage.
в– в– Allow 7 days between application and grazing of lactating animals. There is not waiting period between application
and grazing of non-lactating animals, but remove animals from treated areas at least 30 days before slaughter. Herbicide
Formulation
Product Rate Range
Forefront
3L
1.5 - 2.6 pts
в– в– Forefront is a premix of aminopyralid (Milestone) plus 2,4-D that controls annual, biennial and perennial broadleaf
weeds, including bull, musk, and Canada thistle.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Forefront should generally be applied when perennial weeds are in the bud or early-flower stage. Most effective
control of biennial species will result from application at the end of the first year of growth, or in the following spring
when plants are still relatively small.
в– в– The addition of NIS (0.25 to 0.5% v/v) is recommended for control of weeds with pubescent leaf surfaces or advanced in growth stage, or under adverse environmental conditions (too hot, too dry, etc).
в– в– Forefront can be used in permanent grass pastures and CRP acres. Do not rotate to any other crop within one year
following application. Animals grazing on treated pasture should be grazed on nontreated forage for 3 days before
161
Permanent Grass Pastures/CRP/Grass Hay
moving to areas where sensitive broadleaf crops will be planted in the future. Manure should be left on the pasture
or, if collected at a central location such as a barn, spread on pastures, not cropland. Do not use aminopyralid-treated plant residues, including hay or straw from treated areas, or manure from animals that have grazed forage or
eaten hay harvested from treated areas within the previous 3 days, in compost or mulch that will be spread to areas
where broadleaf plants may be grown.
Herbicide
Formulation
Product Rate Range
Glyphosate
Various
2% v/v (spot treatment only)
в– в– Glyphosate can be used as a spot treatment to control a variety of herbaceous and woody brush species such as
multiflora rose, brambles, poison ivy, and quackgrass. Glyphosate should generally be applied when perennial
weeds are in the bud to flower stage, and woody perennials are fully leafed out. Table 24 contains a list of currently
available glyphosate products. Consult label for recommended timing of application for maximum effectiveness on
target species.
в– в– Glyphosate can be used for site preparation before planting in CRP, postemergence control when grasses are
dormant, and selectively with the use of wiper application equipment. Apply 5 to 8 floz/A in the spring during dormancy. Grasses and forbs that have broken dormancy will be injured.
в– в– Site of action: group 9 (see pages 14-15).
в– в– Spray foliage of target vegetation completely and uniformly, but not to the point of runoff.
в– в– Glyphosate is very effective for the selective killing of multiflora rose near desirable trees, due to the lack of soil activity. However, avoid contact with foliage of desirable nontarget vegetation. Apply in late spring or summer when
multiflora rose are fully leafed out.
в– в– No more than one tenth of an acre of pasture should be treated at one time. Further applications in the same area
may be made at 30-day intervals.
в– в– Do not graze or harvest for 14 days after application.
Grass Pastures
Herbicide
Formulation
Product Rate Range
Metsulfuron methyl (active ingredient)
Accurate/Patriot
60DF
1/10 - 1.0 oz
в– в– Accurate and Patriot are labeled for use in pastures and fallow areas.
в– в– Metsulfuron-methyl is a translocated herbicide for control of broadleaf weeds and brushy plants.
в– в– Site of action: group 2 (see pages 14-15).
в– в– Apply to foliage when weeds and brush are actively growing. For annual weeds, apply in spring or early summer
before weeds are 4 inches tall. Apply when brushy plants are fully leafed out.
в– в– In OSU trials, metsulfuron-methyl has been highly effective for multiflora rose control; foliar applications provide
best control of rose. Apply in late spring or summer when rose plants are fully leafed out. For spot treatment of
multiflora rose, blackberry, or Canada thistle, use 1 ounce of Accurate/Valuron per 100 gallons of water. Metsulfuron-methyl is less effective than Stinger or glyphosate for long-term control of Canada thistle.
в– в– Apply with NIS at a rate of 1 to 2 pints per 100 gallons water (1/2 to 1 pint for tall fescue).
в– в– The maximum use rate for fescue pastures is 2/10 ounce/A. Application to fescue may cause stunting, temporary
discoloration, and seed head suppression. To minimize injury to fescue, apply later in the spring or fall and/or tank
mix with 2,4-D. Bluegrass, orchardgrass, timothy, bromegrass, and bermudagrass pastures have demonstrated
good tolerance. Ryegrass is highly sensitive to metsulfuron-methyl. Grasses should be well-established at time of
application.
в– в– Metsulfuron-methyl is a long-residual herbicide and is labeled with extensive restrictions on over-seeding with
legumes, pasture renovation, and crop rotation (34 months to most crops). Cautionary and other restrictive statements on the pasture label should be read and understood by the user prior to use.
в– в– Allow 4 hours between application and rainfall.
в– в– There is no grazing restriction on the Accurate or Patriot label.
162
Permanent Grass Pastures/CRP/Grass Hay
Herbicide
Formulation
Product Rate Range
Milestone
2L
3 - 7 oz
в– в– Milestone (aminopyralid) controls annual, biennial and perennial broadleaf weeds, including bull, musk, and Canada
thistle.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Milstone should generally be applied when perennial weeds are in the bud or early-flower stage. For Canada
thistle control, apply 5 to 7 oz/A in the spring to plants in the prebud stage, or apply in the fall to plants that have
regrown to a size of at least 8 inches. For control of bull or musk thistle, apply 3 to 5 oz/A in spring or early summer
to rosette or bolting plants, or apply 4 to 5 oz/A in fall to plants in the late bolt through early-flowering stage.
в– в– The addition of NIS (0.25 to 0.5% v/v) is recommended for control of weeds with pubescent leaf surfaces or advanced in growth stage, or under adverse environmental conditions (too hot, too dry, etc).
в– в– Milestone can be used in permanent grass pastures, CRP acres, wildlife areas, and other non-cropland areas. Do
not rotate to any other crop within one year following application. Animals grazing on treated pasture should be
grazed on nontreated forage for 3 days before moving to areas where sensitive broadleaf crops will be planted in
the future. Manure should be left on the pasture or, if collected at a central location such as a barn, spread on pastures, not cropland. Do not use aminopyralid-treated plant residues, including hay or straw from treated areas, or
manure from animals that have grazed forage or eaten hay harvested from treated areas within the previous 3 days,
in compost or mulch that will be spread to areas where broadleaf plants may be grown.
Grass Pastures
Herbicide
Formulation
Product Rate Range
PastureGard
2 EL
2 - 8 pt (broadcast)
50% v/v (basal or cut stump)
в– в– Pasture Guard is premix of triclopyr and fluroxypr for use on permanent pastures, CRP, and other non-crop areas.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Can be applied as a foliar spray, or as a basal bark or cut stump application for woody species. Basal and cut stump
applications must use diesel, kerosene, or other commercial carrier.
в– в– Apply as a basal application to control trumpetcreeper and Virginia creeper.
в– в– There are no grazing restrictions for non-lactating animals. Do not let lactating animals graze treated areas until
the following season after application. Allow 14 days between application and harvest for hay. Animals grazing on
treated forage must be removed from treated forage 3 days before slaughter.
Herbicide
Formulation
Product Rate Range
Plateau
2L
4 to 12 oz
в– в– Controls small annual grass and broadleaf weeds at rates of 4 to 6 oz/A, while rates of 8 to 12 oz/A will control a
number of biennial and perennial weeds. The lower rates should be used for CRP cover that contains legumes.
в– в– Apply with nonionic surfactant (1 qt/100 gallons). Plateau can be more effective when applied with methylated seed
oil (1.5 to 2 pts/A) instead of surfactant, but will be more injurious to the CRP cover. The addition of nitrogen fertilizer solution may improve control of certain weeds, but will also increase risk of injury to CRP cover crops.
в– в– Plateau can be used during the establishment of CRP cover. To minimize injury to grasses, delay application until
they have reached the 5-leaf stage.
в– в– See the Plateau label for information on tolerance of grass and legume species.
Herbicide
Formulation
Product Rate Range
Remedy Ultra/Relegate
4L
1 - 3 pt (broadcast)
в– в– Remedy Ultra (triclopyr) is a translocated herbicide for control of herbaceous broadleaf and woody weeds in permanent grass pastures, CRP, and other non-crop areas.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Can be applied as a foliar spray, or basal bark or cut stump application for woody species.
в– в– Controls only emerged herbaceous weeds that are fully leafed out at the time of application.
163
Permanent Grass Pastures/CRP/Grass Hay
в– в– Will injure desirable broadleaf forbs.
в– в– There are no grazing restrictions for non-lactating animals. Do not let lactating animals graze treated areas until
the following season after application. Allow 14 days between application and harvest for hay. Animals grazing on
treated forage must be removed from treated forage 3 days before slaughter.
Herbicide
Formulation
Product Rate Range
Spike
20P
10 - 20 lb
в– в– Spike (tebuthiuron) controls brush and woody plants, including multiflora rose, in rangeland and grass pastures.
Requires sufficient rainfall to move herbicide into root zone. See label for rates on specific species.
в– в– Site of action: group 7 (see pages 14-15).
в– в– Apply anytime throughout the year except when soil is frozen or saturated with moisture. For best results, apply
prior to the resumption of active seasonal growth in the spring.
в– в– There are no grazing restrictions following the application of Spike.
в– в– May kill or injure desirable legumes and grasses where contact is made. Apply as a spot treatment or when grasses are dormant to minimize injury.
в– в– Do not apply on or near field crops or other desirable vegetation. Do not apply where soil movement is likely. Refer to label for additional restrictions.
Herbicide
Formulation
Product Rate Range
Stinger/Clean Slate
3L
2/3 - 1 1/3 pt
в– в– Stinger (clopyralid) is a translocated herbicide for use in grass pastures and set-aside land.
в– в– Site of action: group 4 (see pages 14-15).
в– в– Controls a limited number of broadleaf weeds, including cocklebur, ragweeds, and nightshade. Controls Canada
thistle at higher rates. Suppresses sowthistle and buffalobur.
в– в– Apply when weeds are young and actively growing. Canada thistle should be at least 4 inches tall or across (rosette), but apply before the bud stage.
в– в– Established grasses are tolerant, but new grass seedings may be injured. Some forages, especially legumes, are
especially sensitive to Stinger. Do not spray pastures containing legumes unless injury can be tolerated.
в– в– Allow 6 to 8 hours between application and rainfall.
в– в– There is no waiting period between application and grazing. Do not use hay, straw, or manure from treated areas
for composting or mulching on susceptible broadleaf crops. Do not transfer animals from treated grazing areas
onto sensitive broadleaf crop areas without first allowing 7 days of grazing on an untreated pasture. Otherwise,
urine may contain enough Stinger to injure sensitive broadleaf plants.
в– в– Apply only once per 12 month period. Wheat, grasses, field corn, or sugar beets may be planted anytime after treatment. Check the label for recrop intervals on other broadleaf crops.
Grass Pastures
Herbicide
Formulation
Product Rate Range
With Glyphosate or Liberty
Yukon
67.5WG
4 - 8 oz
2 - 8 oz
в– в– Yukon is a premix of halosulfuron (Permit) plus dicamba for control of most annual broadleaf weeds and yellow nutsedge. Yukon will also suppress some perennial broadleaf weeds, primarily during the growing season of application.
в– в– Site of action: group 2 (halosulfuron); group 4 (dicamba). See pages 14-15.
в– в– There is no waiting period between application and grazing. Allow 37 days between application and harvest for
hay.
в– в– Weeds should generally be less than 6 inches tall for best results. Use a rate of 6 to 8 oz for yellow nutsedge control.
в– в– Apply with NIS (1 to 2 quarts/100 gallons) or COC (1 gallon/100 gallons). UAN (28% UAN, etc - 2 to 4 quarts/A) or
AMS (2 to 4 lbs/A) can be added to improve control of certain weeds or if required for another herbicide in the
spray mix. Apply in a spray volume of at least 10 gpa.
164
Table 21. Weed Response to Herbicides in Grass Pastures/CRP/Grass Hay
This table compares the relative effectiveness of herbicides on weeds. Ratings are based on labeled application rate and weed
size or growth stage. Control of perennial weeds may require more than one application. Performance may be better or worse
than indicated in the table, due to weather or soil conditions, or other variables.
Curtail
Dicamba
Forefront
Glyphosate
Metsulfuron
Milestone
PastureGard
Remedy Ultra
Stinger
4
4
4
4
9
2
4
4
4
4
8
9
7
9
8
7
9
9
-
-
-
9
-
9
9
8
6
9
8
9
9
7
8
8
6
Cockle, corn
7
-
9
8
7
9
6
9
-
-
-
-
-
Cockle, cow
7
-
9
8
7
9
6
9
-
-
Horseweed (marestail)
9
9
9
9
9
9
9
9
9
8
6
7
9
Mustard spp.
9
8
9
9
9
7
9
9
9
-
-
9
6
Pennycress, field
9
8
9
9
9
8
9
9
9
-
-
-
6
Pepper weed spp.
9
8
9
9
9
7
9
9
9
-
-
-
6
Shepherd's purse
8
8
9
9
8
7
8
9
9
-
-
-
6
Cocklebur, common
8
9
9
9
9
9
9
9
9
9
8
8
9
Lambsquarters, common
8
9
9
9
8
9
9
9
9
9
9
9
6
Nightshade, black
7
9
8
8
7
8
9
8
7
9
-
-
-
Pigweed spp.
8
9
9
8
8
9
8
9
9
8
9
-
6
Ragweed, common
9
9
9
9
9
9
9
9
-
9
9
9
9
Ragweed, giant
9
9
9
9
9
9
9
9
-
9
9
9
9
Velvetleaf
8
7
9
8
8
9
8
8
8
-
9
-
-
Burdock, common
9
9
9
9
8
7
9
9
9
9
9
9
8
Carrot, wild
8
9
9
9
8
7
8
8
9
-
7
8
6
Evening primrose, common
8
8
8
9
7
7
9
9
-
8
-
8
-
Hemlock, poison
7
-
8
9
8
8
7
8
-
-
-
9
-
Lettuce, wild
9
9
9
8
9
8
9
8
9
-
-
-
9
Parsnip, wild
8
9
8
9
8
8
8
8
8
-
-
-
-
Teasel
7
9
9
8
9
8
8
8
9
-
-
-
8
Thistle, bull
8
9
9
9
9
9
9
9
9
9
6
6
9
Thistle, musk
9
9
9
9
9
9
9
9
9
9
6
7
9
Yellow rocket
8
8
9
9
8
8
8
8
9
-
-
-
-
Chaparral
2/4
2,4-D
Crossbow
Weed control rating:
9 = 90% to 100% control
8 = 80% to 90% control
7 = 70% to 80% control
6 = 60% to 70% control
- = not recommended or insufficient information
Cimarron Max
Site of action
4
2/4
Chamomile, mayweed
7
Chickweed, common
Winter annual
-
Summer annual
Grass Pastures
Biennial
165
Crossbow
Curtail
Dicamba
Forefront
Glyphosate
Metsulfuron
Milestone
PastureGard
Remedy Ultra
Stinger
9
8
9
9
9
8
9
9
6
8
7
8
9
8
8
8
6
8
8
9
8
6
7
8
9
9
9
9
6
8
9
8
8
9
8
6
7
9
7
6
6
7
9
6
7
9
8
7
6
8
9
8
8
9
8
7
8
8
9
9
8
6
7
7
7
9
8
9
6
7
8
9
8
8
9
9
7
-
9
7
7
8
8
1
8
9
8
9
9
8
8
7
8
6
7
6
7
7
6
7
6
9
7
7
7
9
7
8
8
8
7
7
7
8
8
9
8
7
7
6
9
6
7
7
7
7
7
7
7
8
8
8
8
8
8
9
7
7
8
6
9
9
6
9
8
9
5
6
8
6
7
8
8
9
9
8
6
9
9
9
8
8
8
8
8
8
8
8
9
8
7
8
8
8
9
7
8
7
9
7
8
8
8
8
8
8
8
9
8
6
9
9
9
9
9
8
7
9
7
9
7
9
8
7
-
9
8
9
9
8
9
9
6
9
8
9
8
9
9
9
7
7
7
8
9
8
8
7
6
7
6
6
9
-
7
8
8
8
8
9
8
9
8
6
7
7
9
5
6
-
9
7
9
6
8
9
8
9
8
8
6
7
7
6
7
7
7
9
7
6
6
7
6
6
6
6
6
6
6
6
6
6
6
6
6
8
8
-
8
8
7
9
6
9
6
6
6
6
6
6
7
7
8
8
7
8
7
8
8
7
8
6
6
7
6
6
6
6
6
6
6
6
6
6
6
7
7
6
6
7
7
7
6
7
8
7
-
7
6
7
7
7
9
8
7
7
7
6
7
8
8
7
9
6
9
6
6
8
7
-
-
7
8
8
8
8
6
6
6
6
7
6
-
CHaparral
8
6
7
8
8
6
8
6
6
8
9
7
8
7
8
6
7
6
7
6
6
7
9
6
7
7
7
6
2,4-D
Herbaceaous perennials
Aster spp.
Bedstraw spp.
Bindweed, field
Bindweed, hedge
Buttercup spp.
Chickweed, mouseear
Chicory
Clover spp.
Cockle, white
Daisy, oxeye
Dandelion
Dock spp.
Dogbane, hemp
Garlic or onion, wild
Goldenrod spp.
Groundcherry spp.
Hemlock, spotted water
Horsenettle
Ironweed
Knotweed, Japanese
Milkweed, common
Nettle, stinging
Plaintain spp.
Pokeweed, common
Snakeroot, white
Sorrel, red
Sowthistle, perenniel
Thistle, Canada
Yarrow, common
Woody Perennials
Blackberry spp.
Dewberry spp.
Grape, wild
Honeysuckle spp.
Locust, black
Multiflora rose
Nightshade, bittersweet
Olive, autumn
Poison ivy, oak
Sumac spp.
Trumpetcreeper
Virginia creeper
Grass Pastures
Cimarron Max
Table 21. (continued)
166
Control of Problem Weeds
The following section outlines strategies and herbicide treatments for management of weeds that are
especially problematic in crop production. For annual
weeds, this usually involves selection of the proper
herbicides and application method. Perennial weeds
require other strategies, such as application of translocated herbicides (glyphosate, dicamba, 2,4-D) in the
fall following wheat harvest when perennials are in an
advanced stage of growth. This allows movement of herbicide into the roots or other underground plant parts.
Perennial weeds can be present in any tillage system,
but tend to be more of a problem in minimum tillage,
due to the lack of disturbance of underground plant
parts. Root systems, rhizomes, tubers, and similar underground parts of perennial plants are a source of reinfestation even when above ground growth is controlled. It
is extremely difficult to eliminate perennial weeds with a
single herbicide application, and effective management
will require attention every year. The following general
strategies should be considered for management of
perennial weeds.
1. Perennial weeds often occur first at the edges of crop
fields, near fencerows and wooded areas. Taking
steps to control perennial weeds in these areas when
infestations are light will prevent further spread into
the rest of the field. This can be accomplished by
tillage or herbicide application in the infested area,
without having to treat the rest of the field.
2. Apply glyphosate, or combinations of glyphosate with
dicamba or 2,4-D, in the fall when perennial broadleaf weeds are in the bud to flower stage, or as late
as possible before a hard frost. Add AMS (17 lb/100
gallon water) to glyphosate for maximum effectiveness on perennial weeds. Perennial grasses should
have at least 10 to 14 inches of growth at the time of
treatment. The best opportunity for this treatment is
in wheat stubble. If the wheat stubble is mowed in
summer to control seed production by annual weeds,
mow before early August to allow time for regrowth
of perennial weeds. It may be possible to apply
herbicide after corn or soybean harvest in the fall, but
allow time for perennials to recover from damage by
harvest equipment.
3. Preplant application of glyphosate, 2,4-D, dicamba
or combinations of these can help reduce the population of early emerging perennial weeds such as
quackgrass and dandelion.
4. Postemergence herbicides can suppress or control
perennial weeds, but this is often limited to suppres-
sion through the growing season. In corn, dicamba,
2,4-D, Stinger, and many ALS inhibitors (Hornet, Beacon, Permit, nicosulfuron) have activity on perennial
broadleaf weeds when applied postemergence. Combinations of an ALS inhibitor with 2,4-D or dicamba
have generally provided the most effective control,
especially for hemp dogbane and perennial vines.
In soybeans, ACCase inhibitors (clethodim, Fusilade,
Fusion, and Assure II) will control or suppress many
perennial grasses, including johnsongrass, quackgrass, and wirestem muhly. Synchrony STS and Classic/Harmony GT combinations can suppress common
milkweed, pokeweed, and perennial sowthistle, and
Basagran can control the above-ground growth of
Canada thistle. Blazer, Cobra, Reflex, and Flexstar can
burn back the above-ground growth of vines, such as
bindweeds and honeyvine milkweed.
5. Postemergence application of glyphosate in glyphosate-resistant soybeans and corn can be a very effective tool for reducing perennial weed populations.
Late postemergence application, when perennial
weeds are in the bud to flower or boot to seedhead
stage, will provide the most effective and complete
plant control. When applied early postemergence,
a second application may be required to control regrowth.
6. Glyphosate can be selectively applied to weeds
in soybeans with a ropewick or sponge applicator.
Weeds should be substantially taller than the soybeans, and herbicide applied in mid- to late-season
for best results. This can be an effective method of
managing hemp dogbane and common milkweed.
7. A preharvest application of approved glyphosate
products in soybeans, corn, or wheat may help
control perennial weeds, since their above-ground
growth is still intact. In wheat and corn, 2,4-D is also
labeled as a preharvest treatment. This treatment
may have to be applied with aerial or high-clearance
ground equipment.
8. Tillage can aid greatly in control of biennial and
perennial weeds, but mainly is effective at removing
those with a single deep taproot, such as pokeweed,
dandelion, and wild carrot. Tillage with a chisel plow,
disk, or field cultivator may actually help spread perennials with creeping root systems, such as Canada
thistle and hemp dogbane.
167
Glyphosate Rates and
Equivalents
Numerous glyphosate products are currently available. OSU and Purdue University research indicates
similar effectiveness among these products, although
labels may vary with regard to rainfast intervals, surfactant recommendations, etc. Glyphosate rates in the
following section are stated as pounds of glyphosate
acid equivalent (ae) per acre. Product rates will vary,
since the concentration of the glyphosate acid varies
among products. Table 24 contains a list of currently
available glyphosate products, and rate equivalents for
these products. Consult labels and local use guides for
specific product rate information.
Jerusalem Artichoke
Jerusalem artichoke is a perennial broadleaf weed
that spreads by seed, rhizomes, and tubers. The tubers
overwinter in the soil and may become as large as a
small potato. Jerusalem artichoke is extremely competitive with all crops and may reach a height of 6 to 8 feet.
The flowers of Jerusalem artichoke resemble those of
annual sunflower, but are much smaller.
Noncrop/Fallow Areas. A 2 percent solution of
glyphosate as a spot treatment provides fair to good
control. For broadcast applications, use 2.25 lbs ae of
glyphosate/A. This treatment will be most efп»їfective when
plants are close to or in the bud stage.
Corn. Postemergence application of Spirit (1 oz/A),
NorthStar (5 oz/A), Stinger (1/2 pt/A), WideMatch (1.3
pts/A), or Hornet (3 to 5 oz/A) will control or suppress
small (3 to 6 inch) artichoke plants. These herbicides
are most effective when mixed with dicamba (NorthStar
is a premix of Beacon and dicamba). Marksman (3.5
pints/A), dicamba (1/2 to 1 pint/A), Status (5 oz/A), 2,4D amine (0.5 lb ai/A), or dicamba + 2,4‑D (1/2 pint + 1/4
pint/A) applied when artichoke are at least 6 inches tall
provides fair to good control. Glyphosate (glyphosateresistant corn) applied at 0.75 lbs ae/A will suppress or
control Jerusalem artichoke, but a second application
may be necessary. Liberty (LibertyLink corn only) applied
postemergence will often suppress artichoke through
the growing season.
Soybeans. Glyphosate (Roundup Ready soybeans)
will suppress or control Jerusalem artichoke. A second
application may be necessary. Late post applications,
when plants are in the early bud stage, will provide the
most complete control of underground plant parts. A
single postemergence application of Classic (3/4 oz/A),
Synchrony XP (0.75 oz/A), Raptor (4 to 5 oz/A), Pursuit
(1.44 ounces/A), or Liberty/Cheetah (29 oz/A - Liberty-
Link soybeans only) will control or suppress artichoke.
Split applications of Classic (1/2 oz/A followed by 1/2
oz/A) will provide more effective control than a single
application. The first Classic application should be made
when artichokes are less than 8 inches tall and have
fewer than 8 leaves, and followed with a second application 14 to 21 days later.
Atriplex
Atriplex is a summer annual weed in the lambsquarters family that is increasing in prevalence throughout
Ohio and eastern Indiana, although most is found north
of Interstate 70. Atriplex resembles common lambsquarters, but often has narrower leaves and emerges
earlier in the season. Orientation of leaves at the base
of the stem is a key difference between lambsquarters
and Atriplex. Atriplex has opposite leaf orientation at
the lowest 4 to 8 nodes and leaves are usually alternate
at all higher nodes. Lambsquarters can have opposite
leaf orientation at the lowest one or two nodes, and all
higher nodes are alternate. Atriplex usually reaches a
maximum height of 3 feet, while lambsquarters can exceed this height. Atriplex has been a problem primarily
in soybeans, where it has survived preplant glyphosate
and 2,4-D application and postemergence Harmony GT
application.
Soybeans. Controlling emerged Atriplex prior to
planting with burndown herbicides is important. Because it emerges early in the spring, Atriplex may have
considerable size at the time of burndown herbicide application. Burndown herbicides seem to be most effective on small plants, while larger plants can be difficult
to control. University research indicates that low rates of
glyphosate mixed with 2,4-D ester are effective on small
plants, and herbicide rates should be increased with
increasing plant size or cold temperatures. Gramoxone
plus 2,4-D ester can also be effective on small plants,
especially when mixed with Synchrony XP. Chlorimuroncontaining products or Python can provide residual control of later-emerging plants, but most other soil-applied
herbicides are variable in effectiveness. Postemergence
application of glyphosate (0.75 to 1.5 lbs ae/A - Roundup
Ready soybeans) will control small Atriplex and help
control plants that escape burndown treatments. Increase glyphosate rates as Atriplex size increases. Most
other postemergence soybean herbicides are ineffective for Atriplex control.
Field and Hedge Bindweed
Field and hedge bindweed are perennial vines that
are similar in appearance. Both are often mistaken for
annual morningglory. However, they are much more
168
difficult to control than annual morningglory because of
their deep, overwintering rootstocks. Tillage and crop
rotation, in combination with selected herbicide use,
helps reduce infestations. Chemical controls are the
same for both types of bindweed.
Noncrop/Fallow Areas. To control bindweeds in
wheat stubble or after corn or soybean harvest, apply
glyphosate (2.25 to 3 lbs ae/A or 2% solution for spot
treatment), glyphosate + 2,4‑D (1.5 lbs ae/A + 0.5 lb ai/A),
or glyphosate + dicamba (1.5 lbs ae/A + 1 pint/A) when
plants are at or past the full‑bloom stage. Apply fall treatments before a killing frost, and do not till for at least 7
days following application. Do not treat weeds under
stress from drought.
Corn. Status (5 oz/A) has provided excellent bindweed control in university research. Application of
NorthStar (5 oz/A), Yukon (6 to 8 oz/A), or combinations of Spirit (1 ounce/A) or nicosulfuron with dicamba
will suppress bindweed plants less than 6 inches tall.
Starane (2/3 pt/A) and WideMatch (1.33 pts/A) suppress
bindweeds. Glyphosate (glyphosate-resistant corn) applied at 1.1 lb ae/A will suppress bindweed, but a second
application may be necessary.
Soybeans. Glyphosate (1.5 lbs ae/A - Roundup Ready
soybeans) will suppress or control bindweeds. A second
application may be necessary. Late postemergence
applications, when plants are in the bloom stage, will
provide the most complete control of underground plant
parts. Postemergence application of Ultra Blazer (2
pints/A), Cobra/Phoenix (12.5 ounces/A), or a fomesafen
product, or combinations of Basagran/Broadloom with
these products may burn back the above‑ground foliage
of bindweeds under favorable conditions. Results are
best with high temperature, high humidity, and good
soil moisture. Apply when bindweeds are from 12 to 18
inches long.
Burcucumber
Burcucumber is an annual broadleaf weed that reproduces by seed. It is more prevalent than wild cucumber
and distinguished from this weed by its white flowers
and flat, egg‑shaped pods. The pods, which are in clusters, bear single seeds and are covered with barbed,
prickly bristles. Burcucumber is extremely competitive,
and vines may spread as far as 25 feet from a single
plant. Seed may germinate throughout the spring and
summer, making season‑long control difficult. The vines
cover soybeans and twine around corn, hindering harvest operations.
Corn. Products that contain high rates of isoxaflutole
(Balance Flexx, Corvus) or mesotrione (Lumax, Lexar,
Instigate) applied preemergence can provide early-
season control of burcucumber, but a postemergence
treatment is also required. While many postemergence
herbicides are effective on small plants, the later‑emerging burcucumber plants often grow rapidly enough to
cause problems. A successful burcucumber control
program often involves preemergence herbicides that
provide early-season control, followed by late postemergence applications when corn is about 25 to 35 inches
tall (sometimes with high‑clearance sprayers) to control
late‑emerging plants. Most effective control results
from use of postemergence herbicides that have foliar
and residual activity on burcucumber, such as Callisto,
Spirit, Zemax, Realm Q, Solstice, or Halex GT (some of
these must be applied when corn is no more than 20
inches tall). Other herbicides with effective activity on
emerged burcucumber include nicosulfuron, Beacon,
Impact/Armezon, Northstar, Status, dicamba, bromoxynil, Yukon, or Liberty (LibertyLink corn). Use drop
nozzles where directed by the label to avoid crop injury
in late postemergence applications. Glyphosate (0.75 lb
ae/A - glyphosate-resistant corn) is effective for control
of small burcucumber plants.
Soybeans. Classic (2/3 to 3/4 ounce/A) and Synchrony XP (0.75 ounce/A) are the most effective postemergence herbicides for control of burcucumber in
soybeans.Glyphosate (Roundup Ready soybeans) and
Liberty/Cheetah (LibertyLink soybeans) will control small
burcucumber. For all of these products, a split application may be more effective than a single application at
a higher rate where late‑emerging burcucumber are a
frequent problem.
Wild Carrot
Wild carrot (also called Queen Anne’s lace) is a biennial weed that is a frequent problem in continuous notillage cropping systems. Infestations often first appear
at the borders of fields and the seed is spread throughout the field by the combine during corn and soybean
harvest. It can be distinguished by its finely divided or
lacy leaf shape, a white flower head, and its carrot-like
odor. Wild carrot spreads by seed. The ultimate goal of
controlling wild carrot, regardless of the method, should
be to prevent seed production. A dense population of
wild carrot can cause severe yield losses in corn and
soybeans. Some wild carrot populations in Ohio are
resistant to 2,4-D.
Wheat Stubble. Mow the wheat stubble before early
August. Apply glyphosate (1.1 to 1.5 lbs ae/A) or glyphosate + 2,4-D (0.75 lb ae/A + 0.5 lb ai/A) in October. This
fall application is targeted at the plants that will flower
and produce seed the following year.
Fall/preplant control. Wild carrot is most effectively
169
controlled by fall application of glyphosate + 2,4-D (0.75
lbs ae/A + 0.5 lb ai/A) or combinations of glyphosate or
2,4-D plus Autumn products or Basis. Apply from early
October into mid November. For best results in spring,
apply glyphosate plus 2,4-D (0.75 to 1.5 lbs ae/A + 0.5
lb ai/A) as an early preplant treatment soon after the
plants begin to green up. Tillage is the most effective
tool for control of wild carrot in the spring.
Corn. Wild carrot can be controlled or suppressed
with postemergence corn herbicides. The most effective postemergence treatments include atrazine (2
pounds active ingredient/A), Spirit (1 ounce/A), Beacon
(3/4 ounce/A), NorthStar, Permit (1 to 1.3 ounces/A),
Yukon, or nicosulfuron. These should be applied with
COC or MSO. Application of any of these herbicides
with dicamba will generally improve control, and the addition of 28% nitrogen may increase effectiveness. Any
postemergence treatment containing at least 1.5 pounds
active ingredient/A of atrazine will provide fair to good
control. Glyphosate (1.1 lb ae/A - glyphosate-resistant
corn) will suppress or control wild carrot.
Soybeans. Most effective control in spring results
from preplant application of glyphosate plus 2,4-D ester
plus a chlorimuron-containing product. Follow fall or
spring preplant treatments with a postemergence application of Classic (3/4 ounce/A), Synchrony XP (3/4
ounce/A), or glyphosate (1.1 lb ae/A - Roundup Ready
soybeans). Use COC or MSO with Classic and Synchrony to maximize control.
Dandelion
Dandelion is a perennial weed that occurs primarily
in no-till fields. Reproduction is by seed and sprouting
from a thick, fleshy root or root segments. Dandelion
stems do not elongate but produce a rosette of leaves.
This weed can become extremely problematic in corn,
soybean, and wheat fields.
Fall herbicide treatments. Dandelion is most effectively controlled with fall herbicide treatments, especially mixtures of 2,4-D plus a chlorimuron-containing
herbicide (Canopy/Cloak DF/EX), Basis, or Autumn
Super. Soybeans must be planted the following year
where chlorimuron is used. Corn or soybeans can be
planted following Autumn Super and Basis (varies by
rate and area for Basis). Other effective treatments
include glyphosate (1.1 lbs ae/A), and a combination of
glyphosate (0.75 lb ae/A) plus 2,4-D (0.5 to 1 lb ai/A). The
mixture of 2,4-D and dicamha has activity on dandelion
but has been less effetcive than the previously listed
treatments. These treatments can be applied in the
fall prior to corn or soybeans. Apply when plants are
at least 4 inches in diameter and after a light frost for
best results. Mid-October to mid-November may be the
best period for application, as long as plants are mostly
green.
Corn. The most effective spring preplant treatments
have been Lumax or Lexar plus 2,4-D ester in OSU and
Purdue University research. A combination of Instigate
and an atrazine premix should have similar activity. Expert + 2,4-D, Balance/Corvus + atrazine + 2,4-D, or other
treatments containing glyphosate and 2,4-D can be
effective, but control has been more variable. Expert or
combinations of glyphosate with other preplant herbicides (without the 2,4-D) can also be effective, but may
be more variable across a range of weather conditions
and dandelion sizes. For best results, do not apply
spring treatments before about April 7 and use water
as the spray carrier. The most effective postemergence
treatments include Status, Laudis/Corvus + atrazine,
and Callisto plus atrazine. Postmergence application of
glyphosate (Roundup Ready soybeans) or Liberty + atrazine (LibertyLink corn) can control or suppress seedling
dandelion and plants that have been injured by preplant herbicides. Postemergence herbicides are best
suited for control of plants that regrow after a relatively
effective fall or spring burndown treatment, and not for
control of plants that were previously untreated.
Soybeans. Preplant application of glyphosate plus
2,4-D ester plus a chlorimuron-containing or a cloransulam-containing herbicide has generally been the most
effective treatment in university research (chlorimuron
can be more effective than cloransulam). Glyphosate
plus 2,4-D ester has been consistently less effective
than treatments containing chlorimuron or cloransulam.
Apply after about April 7 for best results. Postemergence application of Classic (3/4 ounce/A) or Synchrony
XP (3/4 ounce/A) can suppress dandelion plants that
regrow after preplant treatment. Postmergence application of glyphosate (Roundup Ready soybeans) can control or suppress seedling dandelion and plants that have
been injured by preplant herbicides. Postemergence
combinations of glyphosate plus Classic or FirstRate can
be more effective than glyphosate alone.
Wheat. OSU research results indicate that application of tribenuron (Express/Nuance) plus dicamba to
emerged wheat in early November may be the most
effective approach to dandelion control in wheat. Fallapplied Huskie also has activity on dandelion. Preplant
or preemergence application of glyphosate has the
potential to provide some control or suppression, but
will be most effective when glyphosate application can
be delayed until at least mid-November, or after a frost.
Several wheat herbicides can have activity on dandelion
when applied in the spring, but control can vary greatly
170
with dandelion growth stage and weather. Herbicides
with activity in the spring include Express + 2,4-D, and
combinations of Curtail, Stinger, or WideMatch plus
Express/Nuance or 2,4-D (see labels for information on
approved mixtures).
Hemp Dogbane
Hemp dogbane is a tall‑growing, perennial broadleaf
weed often mistaken for common milkweed. It spreads
by seed and overwintering rootstock. Hemp dogbane
tends to appear in areas that have not been tilled for a
number of years.
Noncrop/Fallow Areas. Glyphosate (3 lbs ae/A or 2%
solution for spot treatment) or glyphosate + 2,4‑D (1.1 lb
ae/A + 0.5 lb ai/A) can be applied when dogbane are in
the late‑bud to flower stage of growth. Treatments following crop harvest or mowing should be delayed until
weeds regrow to a mature stage.
Corn. Glyphosate (glyphosate-resistant corn) applied at 1.1 lb ae/A will suppress or control dogbane, but
a second application may be necessary. Most effective
postemergence treatments include Starane (2/3 pt/A),
WideMatch (1.33 pts/A), or combinations of Spirit (1
ounce/A) or Beacon (3/4 ounce/A) plus 1/2 pint/A of 2,4D. Other postemergence treatments with activity include
NorthStar, Yukon, and combinations of dicamba (1/4 to
1/2 pint/A) with Spirit or nicosulfuron. Dicamba (1/2 to 1
pint/A) applied alone will suppress dogbane, with best
results if dogbane plants are at least 8 inches tall. If corn
is less than 8 inches tall, the higher rate can be applied.
Use drop nozzles where directed by the label to avoid
crop injury in late postemergence applications.
Soybeans. Glyphosate (1.5 lb ae/A - Roundup Ready
soybeans) is the only effective postemergence treatment. A second application may be necessary. Late
postemergence applications, when plants are in the bud
to flower stage, will provide the most complete control
of underground plant parts.
Wild Garlic
Wild garlic is a perennial plant that produces underground and aerial bulblets. The leaves are hollow, nearly
round, and attached to the lower half of the stem. The
aerial bulblets of wild garlic contaminate harvested small
grains, especially wheat. Price dockage for garlic‑tainted
grain can be substantial, depending on the degree of
contamination. Wild garlic can also cause off‑flavor in
milk from animals grazing infested pastures. Wild garlic
is found throughout Ohio, Illinois, and Indiana, but creates the most problems in the wheat‑growing areas of
the state.
Wheat. Postemergence application of the higher
rates of a thifensulfuron/tribenuron premix product in
the spring provides good to excellent control. Apply with
surfactant when wild garlic plants are less than 12 inches
tall, with 2 to 4 inches of new growth. For best results,
apply when wild garlic is actively growing under temperatures of 60 degrees or higher. These products can
be applied using 28% UAN as the carrier, but surfactant
recommendations may change. Refer to the label for
more information on application in liquid fertilizer. Peak
(1/4 to 1/2 ounce/A) is also labeled for control of garlic up
to 8 inches tall. The higher rate provides more effective
control of underground bulblets.
Postemergence application of the high rate of
tribenuron or 2,4‑D ester (0.75 to 1.0 lb ai/A) can prevent
formation of the aerial bulblets of wild garlic, but will
not control other parts of the plant. Tribenuron application timing is similar to that described for thifensulfuron/
tribenuron products. Apply 2,4‑D ester from mid‑March
to early April when the air temperatures are 60 degrees
or higher.
Soybeans. Wild garlic infestations in soybeans sometimes require control measures. Effective treatments
include fall or early-spring application of a chlorimuroncontaining product, or preplant application of Synchrony XP (plus 0.5 lb ai/A of 2,4-D, if at least 7 days
before planting). Postemergence application of Classic,
chlorimuron/thifensulfuron combinations, or Synchrony
XP can also be used. Harmony Extra can be applied
14 or more days before soybean planting for control of
emerged wild garlic plants in early spring.
Horsenettle
Horsenettle is a perennial that spreads through
creeping rootstocks, in addition to reproduction by
seed. A distinguishing feature of horsenettle is the bristly stem, which is covered with hairs and spines. Leaves
are alternate, oblong, and lobed, with yellow prickles on
the petioles, midrib and veins. The plant produces juicy,
yellow berries that are about 1/2 inch in diameter and
contain the seeds. Horsnettle is found mainly in no-till
fields, and is difficult to control. It typically emerges after
crop planting, and postemergence herbcides are only
marginally efп»їfective.
Noncrop/Fallow Areas. Application of glyphosate (3
lbs ae/A or 2% solution for spot treatment), dicamba (2
quarts/A), or 2,4-D ester (2.0 lbs ai/A) when horsenettle
is in the late-bud to flowering stage are most effective.
Control ranges from fair to good with these treatments.
Milestone and and Forefront are effective for horsenettle control in permanent grass pastures and other
noncrop areas that will not be rotated into field crops.
Corn. Preplant herbicides are not effective for
171
control of horsenettle. Most effective suppression/control results from postemergence application of Laudis,
Capreno, NorthStar (5 oz), Yukon (6 to 8 oz), or combinations of Spirit (1 ounce/A) or nicosulfuron with 1/4 to 1/2
pint/A of dicamba. Other treatments with activity include
glyphosate (1.1 lb ae/A - glyphosate-resistant corn), dicamba (1/2 to 1 pint/A), and Marksman (3.5 pints/A).
Soybeans. Postemergence application of Classic
(3/4 ounce/A), Synchrony XP (3/4 ounce/A), Pursuit (1.44
ounce/A), or glyphosate (Roundup Ready soybeans) can
suppress horsenettle.
Horsetail (Equisetum)
Horsetail is a perennial weed that reproduces
through spores (instead of seeds) and rhizomes. It is
typically found in wet areas and in no-till production, and
long-term management of horsetail should involve drainage and tillage where possible. Several herbicides have
activity on emerged horsetail, but the lack of leaf tissue
to intercept spray particles reduces herbicide effectiveness. Considerable variation occurs among Equisetum
species with regard to their response to herbicides,
and the following treatments may not be effective in all
populations.
Corn. Flumetsulam (Python, Hornet) is the most
effective herbicide on emerged plants. Plants can be
treated with a preplant application of Python or Hornet,
or a postemergence application of Hornet depending
upon the emergence pattern and date of crop planting.
Postemergence application of Steadfast plus Status can
suppress horsetail.
Soybeans. Preplant application of glyphosate plus
Python can control plants during the season of application and help reduce the severity of future infestations.
Wheat. MCPA can control or suppress horsetail.
Johnsongrass
Johnsongrass is an extremely competitive perennial
grass prevalent in the southern half of Ohio and Indiana,
although it has been observed as far north as Wood
County in northwestern Ohio and Lake and Allen Counties in Indiana. It reproduces both by seed and overwintering rhizomes (large, white, scaly, underground stems).
Control of rhizome johnsongrass is an ongoing process
that should include both cultural and chemical methods.
Most rhizome production occurs when johnsongrass
plants reach 2 or more feet in height and begin producing seed heads. Close grazing or mowing to keep johnsongrass less than a foot tall will greatly reduce rhizome
production.
Noncrop/Fallow Areas. Glyphosate provides excellent control of johnsongrass that is in the boot to head
stage or anytime prior to frost. For spot treatment, use
a 2% solution. For broadcast application, apply 0.75 lb
ae/A glyphosate plus AMS (17 lbs/100 gallons of water)
in a spray volume of 5 to 10 gpa.
Corn. Postemergence application of nicosulfuron,
Beacon, NorthStar, or Steadfast Q provides the most
effective control of established johnsongrass infestations. Rhizome johnsongrass plants should be at least
8 inches tall at the time of application. Glyphosate
(Roundup Ready soybeans) will control seedling and
rhizome johnsongrass. For most effective control of
rhizome johnsongrass, apply after plants are in the boot
stage. Liberty (22 ounces/A - LibertyLink corn), Corvus,
and Laudis can also control seedling johnsongrass, but
will be less effective than the other herbicides listed
here in established johnsongrass infestations.
Soybeans. Postemergence application of Assure II /
Targa (10 ounces/A), Fusilade DX (12 ounces/A), Fusion
(12 ounces/A), or clethodim provides good to excellent
control. Application should be delayed until johnsongrass reaches a height of about 10 to 20 inches (labels
vary with regard to minimum height at the time of application — consult individual labels for more information). Glyphosate (Roundup Ready soybeans) will control
seedling and rhizome johnsongrass. For most effective
control of rhizome johnsongrass, apply after plants are
in the boot stage. For any of these herbicides, a second
application may be necessary to control regrowth. Postemergence application of Liberty/Cheetah (LibertyLink
soybeans) can suppress seedling johnsongrass.
Lambsquarters (triazineresistant)
Triazine‑resistant weeds have developed in areas
where triazine herbicides (atrazine, simazine) have been
used for many years, primarily in continuous corn areas.
The predominant triazine‑resistant weed in Ohio is
lambsquarters, although some triazine‑resistant pigweed
also occurs. Triazine‑resistant weeds are not controlled
by atrazine, simazine, or metribuzin, regardless of the
rate applied. Preemergence herbicides should be used
in lambsquarters control programs, because postemergence herbicides are variable in their effectiveness.
Corn. Preplant or preemergence application of
products containing isoxaflutole (Balance Flexx, Corvus),
flumetsulam (Python, SureStart/TripleFlex, Hornet), mesotrione (Callisto, Lumax, Instigate, Lexar), or saflufenacil
(Verdict, Sharpen) will control triazine-resistant lambsquarters. Preemergence applications of pendimethalin
will also provide control, but may be more variable than
the others. Pyroxasulfone (Zidua, Anthem) and aceto-
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chlor products (Surpass, Harness, etc) provide fair to
good control of triazine-resistant lambsquarters, but a
tank-mix partner or follow-up postemergence treatment
will generally be required for complete control.
Many postemergence corn herbicides can effectively
control triazine-resistant lambsquarters, especially when
used primarily to control plants that escape effective
preemergence herbicide. Using postemergence herbicides as the sole method of control is likely to result in
more variable results. See Tables 5 and 6 for postemergence herbicide ratings.
Soybeans. Metribuzin will not control triazine-resistant lambsquarters, but most other preplant/preemergence broadleaf soybean herbicides provide adequate
control. Lambsquarters can be extremely difficult to
control with postemergence soybean herbicides, especially when they are large or well-established. Best
control results from application of glyphosate (Roundup
Ready soybeans), Harmony GT (1/12 ounce/A), Synchrony STS (3/4 ounce/A), or Raptor (4 to 5 ounces/A) when
plants are less than 4 inches tall. Use of crop oil instead
of surfactant will improve control with Harmony GT or
Synchrony, but may increase soybean injury on non-STS
soybeans. Use of MSO can improve Raptor activity, but
also increases soybean injury. Some lambsquarters
populations have become less sensitive to glyphosate.
Postemergence glyphosate rates of 1.1 to 1.5 lbs a.e./A
can provide more consistent control than lower rates.
Common Milkweed
Common milkweed, like hemp dogbane, is a problem
primarily in continuous no‑till fields. It may grow 4 to 5
feet tall and reproduces by seed and deep, creeping
roots that overwinter and form new plants the following
spring.
Noncrop/Fallow Areas. Apply glyphosate (2.25 lbs
ae/A or 2% solution for spot treatment) when milkweed
are in the late‑bud to flower stage of growth. Glyphosate (1.5 lb ae/A) plus 2,4-D ester (0.75 lb ai/A can
provide good control. Following small‑grain harvest or
mowing, allow milkweed to regrow to a mature stage
prior to treatment.
Corn. Postemergence application of glyphosate (1.1
lb ae/A - glyphosate-resistant corn) will control or suppress milkweed. A second application may be necessary. Late post applications, when plants are in the
bloom stage, will provide the most complete control of
underground plant parts. Products containing dicamba
provide some control or suppression. Apply when
milkweed is at least 8 inches tall. Application of Yukon,
NorthStar, or a combination of Spirit (1 ounce/A) with
dicamba may provide better control than dicamba alone.
Soybeans. Postemergence application of glyphosate
(Roundup Ready soybeans) applied at high rates will
control or suppress milkweed. A second application may
be necessary. Late post applications, when plants are in
the bloom stage, will provide the most complete control
of underground plant parts. Classic (3/4 ounce/A) and
Synchrony STS (3/4 ounce/A) can suppress milkweed
through the growing season.
Honeyvine Milkweed
Honeyvine milkweed is a vining perennial that
spreads by seeds and long, creeping roots. It is more
of a problem in long-term no-till fields. Control is made
difficult by the late emergence and limited leaf area on
young plants.
Noncrop/Fallow Areas. High rates of glyphosate, or
combinations of glyphosate plus 2,4-D ester will provide
some control when applied in fall. Apply when plants are
in the bud to bloom stage or before a light frost.
Corn. Postemergence application of glyphosate
(0.75 lb ae/A - glyphosate-resistant corn) will control or
suppress honeyvine milkweed, but results have been
variable. Make a second application if necessary. Best
control may result from late postemergence application when plants are flowering. Other postemergence
treatments with activity include Starane (2/3 pt/A),
WideMatch (1.33 pt/A), 2,4-D ester (0.25 to 0.38 lb ai/A),
dicamba (1/2 to 1 pint/A), Status (5 oz/A), and dicamba +
2,4-D (half rates of each). Beacon (3/4 ounce/A), nicosulfuron, Spirit (1 ounce/A), and Permit (1 to 1.3 ounce/A)
will suppress small (1 to 6 inch) plants, but these products are likely to be more effective when combined with
2,4-D or dicamba (1/4 to 1/2 pint/A) where allowed by the
label.
Soybeans. Postemergence application of glyphosate
(Roundup Ready soybeans) will control or suppress
honeyvine milkweed, but results have been variable. Apply higher labeled rates and make a second application
if necessary. Best control may result from late postemergence application when plants are flowering. Other
treatments with activity include Flexstar (1.3 pints/A),
Reflex (1.25 pints/A), Ultra Blazer (1.5 pints/A), and Cobra
(12.5 ounces/A) or combinations of any of these with
Basagran. These treatments can burn back the aboveground foliage under favorable conditions, but will not
affect the roots.
Bigroot Morningglory
Bigroot morningglory (also called wild sweet potato)
is a vining perennial that reproduces from seed and
from roots. The roots are yellowish white and may be
several feet long and weigh over 30 pounds. The bulk of
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the root system is often below the plow line. The stems
grow to a length of 10 feet or more, and cause problems
by twining on crops.
Noncrop/Fallow Areas. Application of high rates of
glyphosate (or a 2% solution for spot treatment) in late
August or when plants are in the bud stage can provide
some long-term control.
Corn. Postemergence application of glyphosate
(glyphosate-resistant corn) will control or suppress bigroot morningglory. Apply 1.1 lb ae/A and make a second
application if necessary. Postemergence application of
2,4-D amine (0.5 lb ai/A), 2,4-D ester (0.25 to 0.38 lb
ai/A), or mixtures of these with dicamba and suppress
plants through the season. Status has similar activity. Applications later in the season when plants are in the bud
stage will result in reduction of the morningglory population, but these can be difficult to implement without
injuring corn.
Soybeans. Postemergence application of glyphosate
(Roundup Ready soybeans) will control or suppress bigroot morningglory. Apply higher labeled rates and make
a second application if necessary. Best control may
result from late postemergence application when plants
are in the bud stage. Cobra (12.5 ounces) can provide
limited suppression of vines.
Wirestem Muhly
Wirestem muhly is a perennial grass that spreads
by seed and short, scaly rhizomes. The rhizomes, like
those of johnsongrass or quackgrass, can be moved
from farm to farm by tillage equipment. Wirestem muhly
does not begin growth until late spring after the crop
has emerged, making it more difficult to control than
quackgrass.
Noncrop/Fallow Areas. Glyphosate can be used as a
preplant treatment in early June where crop planting is
delayed, or it can be applied after harvest when wirestem muhly is at least 8 inches tall and actively growing.
For best results, apply at least 0.75 lb ae/A of glyphosate plus AMS (17 pounds/100 gallons water) in a spray
volume of 5 to 10 gpa. For spot treatments, use a 2%
solution.
Corn. Glyphosate (0.75 lb ae/A - glyphosate-resistant
corn) is the most efп»їfective herbicide for wirestem muhly.
Plants should be at least 8 inches tall at the time of application.
Soybeans. Postemergence application of Assure II/
Targa (8 ounces/A), Fusilade DX (12 ounces/A), Fusion
(8 ounces/A), or clethodim provides good to excellent
control. Apply Assure II or clethodim when wirestem
muhly is 4 to 8 inches tall. Apply Fusilade or Fusion
when plants are 4 to 12 inches tall. Glyphosate (Roundup
Ready soybeans) will control wirestem muhly. Plants
should be at least 8 inches tall at the time of application.
For any of these treatments, a second application may
be necessary to control regrowth.
Eastern Black Nightshade
Eastern black nightshade, a summer annual weed,
develops late in the growing season and produces
purple berries that stain harvested grain. Nightshade
can be identified by the purple color on the underside of
the older leaves. It is a shade‑tolerant plant that can survive underneath the crop canopy. In addition to reducing
yields and crop quality, the succulent plant and berries
can “gum up” a combine so badly that it will not clear
grain properly. Nightshade is a problem in soybeans primarily. Most effective control results from a combination
of preemergence and postemergence herbicides.
Soybeans. Preplant or preemergence applications
of many preplant/preemergence soybean herbicides
will control black nightshde, but products that contain
only chlorimuron and/or metribuzin will not. A follow up postemergence treatment may be necessary
to control plants that emerge in mid-season. Several
postemergence products are effective on eastern black
nightshade if applied when weeds are small. These
include Ultra Blazer (1.5 pints/A), Cobra (12.5 ounces/A),
fomesafen products (Flexstar, Dawn, etc), Pursuit (1.44
ounce/A), Raptor (4 to 5 ounces/A), glyphosate (0.75
lb ae/A - Roundup Ready soybeans), and Liberty/Cheetah (29 oz/A - LibertyLink soybeans). Pursuit provides
residual nightshade control, while most other postemergence herbicides have little to no residual activity.
Yellow Nutsedge
Yellow nutsedge is a perennial sedge that reproduces mainly by small, overwintering tubers located at the
ends of rhizomes. The tubers begin sprouting about May
1 in Ohio. The plant looks like a grass, but has a triangular stem. It is more of a problem in wet areas and during
wet years.
Corn. Alachlor, acetochlor, metolachlor/s-metolachlor,
and Outlook can provide good control, but surface applications are variable in activity. Preplant incorporation
(2 to 3 inches deep) of these materials will provide more
consistent nutsedge control than preemergence application. Control also is enhanced by combining atrazine
with these herbicides.
Postemergence application of Permit (1 to 1.3
ounces/A) or Yukon (6 to 8 oz/A) when nutsedge is
4 to 12 inches tall provides the most effective control.
Basagran (1.5 to 2 pints/A) or Laddok (2.3 pints/A) applied postemergence when nutsedge is 6 inches tall
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also suppresses or controls nutsedge, but is less effective than Permit for reduction of nutsedge populations.
Atrazine plus COC may be used as a postemergence
spray to control emerged yellow nutsedge when small.
Postemergence applications of glyphosate can control
nutsedge, but activity is usually slow.
Soybeans. Alachlor, metolachlor/s-metolachlor, and
Outlook can provide good control, but surface applications are variable in activity. Preplant incorporation (2 to
3 inches deep) of these materials will provide more consistent nutsedge control than preemergence application.
Postemergence application of Basagran (1ВЅ to 2
pints/A) when plants are at least 6 inches tall provides
good nutsedge control. Classic (1/2 to 3/4 ounce/A) or
Synchrony STS (3/4 ounce/A) provides good control of
yellow nutsedge plants with 4 to 6 leaves. Postemergence application of glyphosate can control nutsedge,
but activity is usually slow.
Common Pokeweed
Common pokeweed is a perennial broadleaf weed
that reproduces by seed and also has an enlarged taproot that over-winters to provide a source of new growth
the following spring. This plant is becoming more
prevalent as no-tillage continues to increase. Common
pokeweed can be identified by its pinkish-red colored
stem and its fleshy appearance and alternate leaf pattern. The plant produces many purple berries that can
stain soybeans at harvest.
Noncrop/Fallow Areas. Apply glyphosate at 1.1 to 1.5
lbs ae/A, or at 0.75 lb ae/A in combination with 2,4-D ester (0.5 to 0.75 lb ai/A) in late September or early October when plants are 8 to 24 inches tall, but before frost.
For spot treatment, apply glyphosate in a 2% solution.
Cut Stump Treatments. Application of undiluted
glyphosate directly to the freshly cut stump of pokeweed can provide effective control. Plants should be
several feet tall at the time of cutting for best results.
Corn. Glyphosate (1.1 lb ae/A - glyphosate-resistant
corn) applied postemergence when plants are at least
8 inches tall will control or suppress pokeweed. Make a
second application if necessary. Other efп»їfective postemergence treatments include NorthStar, Yukon, Callisto,
dicamba (1 pint/A), Status (5 oz/A), or a combination of
dicamba with Spirit (1 ounce/A). Apply when plants are
less than 12 inches tall.
Soybeans. Glyphosate (1.1 to 1.5 lb ae/A - Roundup
Ready soybeans) applied postemergence when plants
are at least 8 inches tall will control or suppress pokeweed. Control will be reduced where glyphosate is applied to very small plants, or too late in the season when
plants are extremely large. Make a second application
if necessary. Synchrony STS (3/4 ounce/A) and Classic/
Harmony GT combinations will often suppress pokeweed through the growing season. Thorough spray
coverage on the foliage of larger plants is essential to
maximize herbicide activity.
Quackgrass
Quackgrass is a cool season perennial grass reproducing from seed and a dense network of small rhizomes. Weed growth often begins in early March if there
are a few successive warm days. It tends to be the
biggest problem where grass or grass/legume forage
mixtures are grown or in areas where continuous no‑till
corn is grown. Growth of quackgrass is most vigorous
during the spring, while temperatures are relatively cool.
Noncrop/Fallow Areas. Apply glyphosate in the
spring or fall when quackgrass is at least 6 to 8 inches
tall and actively growing. Apply at a rate of 0.75 lb ae/A
plus AMS (17 pounds/100 gallons water) in spray volume
of 5 to 10 gpa. For spot‑treatment, use a 2% solution.
Corn. Atrazine provides some suppression or control
of quackgrass when split‑applied at high rates, but the
current atrazine label allows a maximum of only 2.5
pounds per year. This rate may not be sufficient in many
fields, and additional herbicides or applications will usually be necessary.
Glyphosate (0.75 lb ae/A - glyphosate-resistant corn)
will control quackgrass that is at least 8 inches tall. Postemergence application of nicosulfuron, Steadfast Q (3/4
ounce/A), or Beacon (3/4 ounce/A) will provide good to
excellent control of quackgrass up to 8 or 10 inches tall.
Capreno and Laudis have activity on quackgrass also.
Soybeans. Postemergence application of Assure II/
Targa (10 ounces/A), Fusilade DX (12 ounces/A), Fusion
(12 ounces/A), or clethodim provides good to excellent
control. These products should be applied when quackgrass is about 6 to 10 inches tall. Glyphosate (Roundup
Ready soybeans) will control quackgrass that is at least
8 inches tall. For any of these herbicides, a second
application at a lower rate may be necessary to control
regrowth.
Common Ragweed (herbicideresistant)
Many common ragweed populations in Ohio and
Indiana are resistant to group 2 herbicides (Classic,
FirstRate, Beacon, etc), especially in fields with a history
of non-GMO soybeans. Populations with multiple herbicide resistance, to both group 2 and 9 or group 2 and
14 herbicides (Flexstar, Cobra, Valor) have also been indentified. In the populations investigated so far, all of the
175
group 9-resistant populations have also been resistant
to group 2. Common ragweed with resistance to both
group 2 and 14 herbicides can be controlled by postemergence application of glyphosate in Roundup Ready
soybeans. Likewise, populations with resistance to
both group 2 and 9 herbicides can still be controlled by
Flexstar or Cobra. However, the most effective management strategy for multiple-resistant populations may be
to plant corn, in order to take advantage of the effectiveness of corn herbicides on herbicide-resistant ragweed.
Use of Liberty/Cheetah in LibertyLink soybeans can also
be an effective tool to manage populations that have
been poorly controlled by other types of herbicides.
Corn. Herbicide-resistant common ragweed populations should not be difficult to control in corn, due to
the effectiveness of triazines, dicamba, and other corn
herbicides. Preemergence corn herbicides can provide
season-long control of common ragweed, when used
at recommended rates. In glyphosate-resistant corn
fields with history of poor performance of glyphosate on
common ragweed, postemergence herbicide treatments
should include other herbicides along with glyphosate if
the preemergence herbicides fail to adequately control
the ragweed. Most effective partners for glyphosate in
these mixtures include Status, Impact, Callisto, Laudis,
and dicamba. The rate of the partner herbicide should
be high enough to control common ragweed that appears to be resistant to glyphosate. In LibertyLink corn,
postemergence application of Liberty or Liberty plus
atrazine effectively controls ragweed plants that escape
residual herbicides.
Soybeans. It is essential that no-till soybean fields
with resistant populations receive an effective burndown
treatment with 2,4-D ester to ensure that that the field is
weedfree at the time of planting. A combination of preemergence and postemergence herbicides will provide
the most effective control of populations resistant to
group 2 and/or group 9 (there are no effective preemergence herbicides where the ragweed is resistant to both
group 2 and 14). Where the population is known to still
be sensitive to group 2, any of the following preemergence herbicides can provide effective control: Canopy/
Cloak, FirstRate, Gangster, Valor XLT, Envive, Sonic,
Authority First/XL/MAXX, Trivence, or Scepter. Where
the population is group 2 -resistant, but still sensitive to
group 14, flumioxazin products, Trivence, Prefix, Intimidator, or metribuzin can provide fair to good control.
Postemergence application of glyphosate (Roundup
Ready soybeans) should control any common ragweed
population that is not glyphosate-resistant. Liberty/
Cheetah (29 oz/A - LibertyLink soybeans) will control
common ragweed that is resistant to group 2, 9, or 14
herbicides. Flexstar (1.3 pts) or Cobra/Phoenix (12.5 oz)
will control populations that are resistant to both group
2 and 9, although Flexstar has been more effective in
OSU research. Apply postemergence herbicides when
ragweed plants are no more than 6 inches tall for most
effective control. Where it is necessary to mix Flexstar
or Cobra with glyphosate to control glyphosate-resistant
plants, apply with the adjuvants specified on the labels
for these products. This is likely to result in the use of
MSO or COC. Similarly, Flexstar GT should be applied
with COC or MSO in glyphosate-resistant populations.
Giant Ragweed
This annual weed emerges as early as March and
will continue to germinate through the spring and early
summer. Giant ragweed is extremely competitive and is
most difficult to control in soybeans and other broadleaf
crops. Its ability to germinate and emerge from deep in
the soil allows it to escape many soil‑applied herbicides.
The most dense populations occur in tilled soil. Populations can decrease in long-term no-till with proper management. Many populations of giant ragweed in Ohio
and Indiana are resistant to group 2 herbicides (Classic,
FirstRate, Beacon, etc), especially in fields with a history of non-GMO soybeans. Populations with resistance
to glyphosate (group 9) have also been identified, and
some of these have multiple-resistance, to both group 2
and 9.
Corn. Early-emerging giant ragweed plants should
be removed prior to planting with tillage or a preplant
herbicide treatment. A preplant application of 2,4‑D
ester (0.5 lb ai/A) plus atrazine provides effective control
of giant ragweed plants that emerge early in the spring
before planting. For preplant control of large plants, the
addition of glyphosate or Gramoxone may be necessary.
A combination of preemergence followed by postemergence herbicides provides the most effective giant
ragweed control, and this approach should be used in
any field where control of giant ragweed has been inadequate in previous years. Most effective preemergence
treatments are those that contain atrazine and another
broadleaf herbicide with activity on giant ragweed.
These include Lumax, Lexar, or a combination of atrazine and one of the following: SureStart/TripleFlex, Instigate, Hornet, Balance Flexx, Corvus, or Verdict/Sharpen.
A follow up postemergence treatment is usually
necessary in fields infested with giant ragweed, and
some preemergence products are intended for use only
in preemergence plus postemergence programs. Many
postemergence corn herbicides will control giant ragweed, especially if they contain atrazine or dicamba (see
Tables 5 and 6 - corn herbicide effectiveness ratings).
In glyphosate-resistant corn fields with a history of poor
176
performance of glyphosate on giant ragweed, postemergence herbicide treatments should include other herbicides along with glyphosate. Most effective partners
for glyphosate in these mixtures include Status, Impact/
Armezon, mesotrione products, Laudis, and dicamba.
The rate of the partner herbicide should be high enough
to control giant ragweed that appears to be resistant to
glyphosate. In LibertyLink corn, postemergence application of Liberty or Liberty and atrazine effectively controls
ragweed plants that escape residual herbicides.
Soybeans. A combination of preemergence followed
by postemergence herbicides provides the most effective giant ragweed control, and this approach should
be used in any field where control of giant ragweed has
been inadequate in prior years. Early-emerging giant
ragweed plants should be removed prior to planting
with tillage or a preplant herbicide treatment. While 2,4D ester alone can control small plants, it should be combined with glyphosate or Gramoxone when plants are
more than a few inches tall. Where the use of 2,4-D is
not possible, application of saflufenacil (Sharpen, Optill
PRO, or Verdict) plus either glyphosate or Liberty/Cheetah, or a combination of Liberty/Cheetah and metribuzin
should be effective. Glyphosate is somewhat variable
for burndown of early-emerging giant ragweed plants,
and use of the appropriate rate based on plant size is
important. The addition of 2,4-D ester or saflufenacil is
also recommended for consistently effective control, especially in fields with a prior history of poor glyphosate
performance on giant ragweed.
Include herbicide(s) with residual activity in the preplant burndown treatment (or apply these after planting where tillage is used), which involves the use of
Scepter or a product containing chlorimuron or cloransulam. These herbicides will reduce the giant ragweed
population and slow the growth of remaining plants to
build more flexibility in the postemergence application
window. None of these herbicides will control group-2
giant ragweed, however. Prefix and Intimidator can
provide some residual group 2 -resistant giant ragweed
control, but their activity is variable, and the field cannot
be treated POST with any fomesafen products where
these PRE herbicides are used.
Where residual herbicides have been applied and
are effective, or the giant ragweed population is very
low, it may be possible to obtain adequate control with
a single postemergence application. However, where
ragweed populations are moderate to dense, early
postemergence herbicide applications need to be followed by a second application to control late‑emerging
plants. The most effective postemergence treatments
for control of giant ragweed (4 to 8 inches tall), that are
not herbicide-resistant, in non-GMO soybeans include:
FirstRate (0.3 ounce/A), Flexstar (1.3 pints/A), or FirstRate
+ Flexstar (0.3 ounces + 1 pint/A). Results with Classic
and Synchrony XP have been more variable than with
FirstRate. In STS soybeans, combinations of Synchrony
XP plus Cobra will provide more consistent control than
Synchrony alone. FirstRate, Classic, Synchrony, and
Pursuit do not control group 2-resistant ragweed.
In Roundup Ready soybeans, make an initial postemergence application of glyphosate when ragweed are
about 6 to 10 inches tall. Glyphosate rate for this application should be 1.1 to 1.5 lbs ae/A (use the higher rate
in fields where giant ragweed has not been adequately
controlled in the past). Make a second application of
glyphosate (0.75 lbs ae/A) three to four weeks later as
needed to control later-emerging plants or to improve
control of plants that survive the first application. In continuous Roundup Ready soybean fields and fields with
a history of giant ragweed control problems (but where
glyphosste still has substantial activity), it is essential to
make two postemergence glyphosate applications at
the rates and timings indicated here (in addition to the
use of a burndown with 2,4-D and residual herbicides
as described above). Failure to do so is likely to result
in giant ragweed escapes later in the season, and these
plants will be extremely difficult to control.
Use of Liberty/Cheetah in LibertyLink soybeans and
can be an excellent tool to manage giant ragweed,
especially those populations that have become resistant
to ALS inhibitors or glyphosate. Apply Liberty/Cheetah
(29 oz/A) postemergence initially when ragweed plants
are about 4 to 8 inches tall. Make a second application
(22 oz/A) about three weeks later as needed to control
later-emerging plants or to improve control of plants that
survive the first application.
Herbicide-resistant giant ragweed. Giant ragweed
populations with group 9 resistance occur in Ohio and
Indiana, and some populations have resistance to both
group 2 and 9. Postemergence control of these populations in soybeans can be extremely difficult, and the
most effective management strategy may be to plant
corn, in order to take advantage of the effectiveness of
corn herbicides on resistant ragweed. It is essential that
no-till soybean fields with resistant populations receive a
preplant treatment of 2,4-D ester, to ensure that that the
field is weedfree at the time of planting. Preemergence
soybean herbicides listed in the previous section can be
included in the preplant herbicide treatment, although
they will not control plants that are group 2-resistant
(they may still have activity on the plants in the population that are not resistant).
Use of Liberty/Cheetah in LibertyLink soybeans is the
most effective tool for management of glyphosate-resistant giant ragweed populations. Apply Liberty/Cheetah
177
(29 oz/A) postemergence initially when ragweed plants
are about 4 to 6 inches tall. Make a second application
(22 oz/A) about three weeks later as needed to control
later-emerging plants or to improve control of plants that
survive the first application. OSU and Purdue research
has shown that resistant populations can also be managed with multiple applications of group 14 herbicides
(Flexstar, Cobra), although this approach may lead to
the development of resistance to these herbicides as
well. The best approach is to make an initial application of Flexstar (1.3 to 1.6 pts/A) or Flexstar GT when
plants are 4 to 8 inches tall. This should be followed
with postemergence application of Cobra (10 oz/A) three
to four weeks later. Where a PPO inhibitor is mixed
with glyphosate to control glyphosate-resistant plants,
apply with the adjuvants specified on the labels for the
Flexstar or Cobra in order to optimize their activity. This
is likely to result in the use of MSO (Flexstar) or COC
(Cobra), and one of these adjuvants should be added to
Flexstar GT in this situation also.
Perennial Sowthistle
Perennial sowthistle is a perennial broadleaf weed
that spreads by seed and creeping roots. Identifying
characteristics are a smooth stem with milky juice and
a whitish coating on the surface, long lobed leaves with
spiny edges, and yellow flower that is about 1ВЅ inches
across.
Noncrop/Fallow Areas. Apply glyphosate (2.25 lbs
ae/A or a 2% solution for spot treatment) when plants
are in the full‑rosette stage for fair to good control. Effective control can be obtained using dicamba (2 quarts/A)
or 2,4-D ester (2 lb ai/A) when plants are in the bud to
flower stage. Avoid tillage for 7 days after application.
Corn. Atrazine applied preplant/preemergence (1.5
pounds/A) or postemergence (2 pounds/A) can provide
good control of sowthistle. Dicamba (1/2 to 1 pint/A),
Status (5 oz/A), or Marksman (3.5 pints/A) provide fair
control when applied to sowthistle at least 6 inches
tall. Apply dicamba with drop nozzles if corn is more
than 8 inches tall to avoid crop injury. Stinger (1/3 to 2/3
pint/A) or Hornet (3 to 5 oz/A) provides fair control when
applied at the rosette to bud stage. Postemergence application of glyphosate (1.1 lb ae/A - glyphosate-resistant
corn) will control or suppress sowthistle.
Soybeans. Preplant or premeergence applications
of a chlorimuron-containing product provides fair to
good control. Postemergence application of Classic
(3/4 ounce/A) or Synchrony XP (3/4 ounce/A) when
sowthistle are in the early‑ to mid‑rosette stage provides
suppression to fair control. Postemergence application
of glyphosate (Roundup Ready soybeans) will control or
suppress sowthistle.
Wheat. Application of high rates of tribenuron or a
thifensulfuron/tribenuron premix product when sowthistle are 4 to 8 inches tall provides fair control. Stinger (1/3
pint/A) or Curtail (2 to 2 2/3 pints/A) provides fair control
when applied at the rosette to bud stage.
Star-of-Bethlehem
Star-of-Bethlehem is a bulbous perennial emerging in early spring and maturing in late spring or early
summer. The leaves of this weed appear grass-like, and
are green and fleshy with a prominent whitish midrib.
The leaves originate from a central bulb. Flowers have
6 white petals with a green stripe on the underside of
each petal. Star-of-Bethlehem has been most problematic in no-till soybean fields, but is also found in no-till
corn. The thick vegetation and bulb density of this plant
can interfere with crop establishment and reduce crop
vigor.
All Crops. The most effective preplant treatment is
Gramoxone SL applied at 2 to 3 pts/A. This treatment
will provide control during the season of application and
also reduce the severity of future infestations.
Corn. Preplant application of atrazine provides fair
control during the season of application, but will not
reduce the population.
Soybeans. Preplant application of a flumioxazin
product can suppress star-of-Bethlehem during the season of application, but will not reduce the population.
Canada Thistle
Canada thistle is a perennial weed that spreads
both by seed and creeping roots. Canada thistle plants
emerge early in the spring and tend to grow in dense,
spreading patches. This weed is extremely competitive
and can be a problem in all crops.
Noncrop/Fallow Areas. The most effective treatment
for control of Canada thistle is glyphosate applied in late
spring or early fall when thistles are in the bud‑to‑flower
stage. Fall treatment will be most successful when
thistles have been mowed or clipped off earlier in the
season and allowed to regrow to the bud stage (or to
a height of at least 10 to 14 inches). This method may
be used in noncrop areas and fallow fields, or following
small‑grain harvest.
For fall treatment, apply 0.75 lb ae/A of glyphosate
plus AMS (17 lbs per 100 gallons water) in a spray volume of 5 to 10 gallons per acre, or 1.5 lb ae/A of glyphosate in spray volumes greater than 10 gallons per acre.
For most effective control of thistle, do not mix other
herbicides with glyphosate. High rates (1 to 2 quarts/A)
of dicamba or 2,4‑D are generally less effective than
178
glyphosate, but a low‑cost application of 2,4‑D will provide some long‑term control of thistle. Alternatively, any
of these herbicides may be applied as a spot treatment
using a 2 percent solution. Treatment with glyphosate,
dicamba, or 2,4‑D in this manner should be delayed until
thistles regrow enough to begin producing buds, or applied as late in the fall as possible. Thistle plants will survive a few light frosts, but apply before the first freeze.
Wheat. Stinger (1/3 pint/A), Curtail (2 to 2 2/3 pts/A),
and combinations of 2,4-D with high rates of Express/
Nuance controls or suppresses Canada thistle, preventing harvest problems. Stinger provides the most complete thistle kill, but is more expensive than the other
three herbicides. Huskie, or dicamba + 2,4‑D will also
often suppress Canada thistle to the point that it does
not interfere with harvest.
Corn. Most effective postemergence control of the
entire plant results from application of Stinger (2/3
pint/A), Hornet (4 to 5 ounces/A) plus a few ounces of
Stinger, or glyphosate (1.1 lb ae/A - glyphosate-resistant
corn). Apply Stinger/Hornet when thistles are at least 4
inches tall and before the bud stage. Glyphosate should
be applied when thistles are in at least the bud stage
for best results; earlier applications will control thistle
through the growing season.
Status (5 oz/A) or Hornet (4 to 5 ounces/A) will effectively control the above-ground part of the plant.
Postemergence application of Basagran/Broadloom (1
quart/A), Laddok (2.3 pints/A), or Liberty plus atrazine
(LibertyLink corn) will control above-ground growth of
actively growing Canada thistle in the 8-inch to bud
stage. Other treatments with activity on thistle include
Buctril/atrazine, Marksman, dicamba, dicamba + 2,4-D,
NorthStar, Yukon, and combinations of Spirit, Steadfast,
Lightning (Clearfield corn only) or nicosulfuron with
dicamba. Most of these treatments will control or suppress the above‑ground part of the plant, which will help
prevent further spread.
Soybeans. Glyphosate (1.1 lb ae/A - Roundup Ready
soybeans) is the most efп»їfective postemergence treatment. Late post applications, when plants are in the bud
to flower stage, will provide the most complete control
of underground plant parts. To prevent yield loss where
thistle populations are high, apply when thistles are
small and retreat regrowth as necessary. Postemergence applications of Basagran (2 pints/A) will control
above‑ground parts of the plant or suppress growth of
Canada thistle. Regrowth usually occurs, but this treatment will reduce competition from Canada thistle in soybeans and help prevent production of more rootstock.
Apply when thistle plants are from 8 inches tall to the
bud stage. COC should be included in the spray mixture.
A second application at the same rate may be made 7 to
10 days later, if necessary. Other products and mixtures
with activity on thistle include Flexstar and mixtures of
Basagran with Reflex, Flexstar, Ultra Blazer, or Cobra.
Postemergence application of Pursuit (1.44 ounces/A),
Classic (2/3 to 3/4 ounce/A), FirstRate (0.3 oz/A), and
Synchrony XP (3/4 ounce/A) may also suppress thistle
growth, but results have been variable.
Waterhemp
Waterhemp is an annual weed that closely resembles
smooth and redroot pigweeds that is abundant in Illinois
and indiana, and starting to spread throughout Ohio.
Waterhemp has no hair on the stem or leaves, while
most other pigweeds have some hair. It often has a long
and narrow leaf shape with wavy leaf margins and a
shiny or glossy appearance. While a number of herbicides are effective for control of waterhemp, this weed's
ability to germinate and emerge late in the season make
it difficult to control with one herbicide application. The
increase in population of this weed seems to also be
due to its greater tolerance to herbicides in general,
compared to other pigweeds,and especially to group 2
and 9 herbicides. Waterhemp populations across the
north central region have developed resistance to herbicides in groups 2, 5, 9, 14, and 27 and many are resistant
to multiple sites of action.
Corn. Many preplant/preemergence corn herbicides
provide effective control of waterhemp, especially when
mixed with atrazine (see Table 7 - corn herbicide effectiveness ratings). A follow-up postemergence treatment
may be necessary in dense populations or if rainfall
promotes emergence later in the season. Postemergence treatments containing atrazine, 2,4-D, dicamba,
Status, mesorione products, Laudis, Corvus, Impact, and
glyphosate (glyphosate-resistant corn) are effective.
Liberty plus atrazine (LibertyLink corn) will control small
waterhemp.
Soybean. For best results, start with a preplant or
preemergence herbicide with activity on waterhemp
(See Table 18 - soybean herbicide effectiveness ratings). Preemergence herbicides will greatly reduce
the waterhemp population, and provide more flexibility
in the postemergence application window. A postemergence treatment will usually be required to control
late-emerging plants. Effective postemergence treatments include Ultra Blazer, Cobra, a fomesafen product
(Flexstar, Dawn, etc.) and Liberty/Cheetah (LibertyLink
soybeans), which should be applied when waterhemp
plants are less than 4 inches tall. Glyphosate (Roundup
Ready soybean) can be effective where the waterhemp
population is not resistant to glyphosate.
179
Volunteer corn
The risk of volunteer corn varies from year to year,
depending upon the severity of problems with stalk
breakage and unharvested ears in the previous fall.
Much of the volunteer corn is now resistant to glyphosate or glufosinate, and some has resistance to both
herbicides. As a result, volunteer corn will often not
be controlled in soybeans by postemergence application of glyphosate or Liberty, and the addition of a
postemergence grass herbicide will be required. These
herbicides should be added to the first postemergence
application in a Roundup Ready soybean field, which will
ensure effective control of small volunteer corn.
Soybeans. In non-GMO soybeans, any type of volunteer corn can be controlled by inclusion of Assure
II/Targa, Select Max, Fusion, Fusilade or clethodim in
postemergence herbicide programs. Activity of most of
these herbicides is maximized by use of COC or MSO,
plus AMS (NIS + AMS should be used with Select Max).
Control can be more variable when applied in a mixture
with a glyphosate product that contains surfactant, in the
absence of COC or MSO. Follow local recommendations and product literature that can specify use of COC
or MSO in mixtures with glyphosate.
Corn. Volunteer corn can be impossible to control in
continuous corn, especially when the volunteer plants
have resistance to both glyphosate and Liberty. Several
scenarios can occur in continuous corn, as follows: 1)
where non-GMO corn was planted in 2010, glyphosateresistant or LibertyLink corn can be planted in 2011, and
treated with glyphosate or Liberty; 2) where LibertyLink
corn was planted in 2010, glyphosate-resistant corn can
be planted in 2011, and treated with glyphosate; or 3)
where glyphosate-resistant corn was planted in 2010,
LibertyLink corn can be planted in 2011, and treated with
Liberty. Glufosinate can be somewhat variable for control of volunteer corn, but has the potential to at least
suppress it to the point of being non-competitive. There
are no options for control of volunteer corn where the
previous year's corn had both glyphosate resistance and
LibertyLink traits.
180
Table 22. Corn and Soybean Herbicide Premix Information
Liquid Premixes for Corn
Name
Active Ingredients (lbs active/gallon)
Formulation Equivalents
Anthem 2.15L
pyroxasulfone (2.09)
fluthiacet-methyl (0.063)
10 oz =
3 oz Zidua 85DF
+ 0.7 oz Cadet 0.91L
Anthem ATZ 4.5L
atrazine (4)
pyroxasulfone (0.485)
fluthiacet-methyl (0.014)
2.5 pts =
1.25 lb ai atrazine
+ 2.85 oz Zidua 85DF
+ 0.61 oz Cadet 0.91L
Bicep II Magnum 5.5L/
Cinch ATZ/Charger Max ATZ
S-metolachlor (2.4)
atrazine (3.1)
2.1 qts =
1.3 pts Dual II Magnum 7.64EC
+ 1.6 lbs ai atrazine
Buctril/atrazine 3L
or Moxy/atrazine 3L
bromoxynil (1.0)
atrazine (2.0)
2 pts =
1 pt Buctril/Moxy 2S
+ 0.5 lb ai atrazine
Callisto GT 4.18L
mesotrione (0.38)
glyphosate (3.8)
2 pts =
3 oz Callisto 4L
+ 0.95 lb glyphosate acid
Callisto Xtra 3.7L
mesotrione (0.5)
atrazine (3.2)
24 oz =
3 oz Callisto 4L
+ 0.6 lbs ai atrazine
Capreno 3.45L
tembotrione (2.88)
thiencarbazone-methyl (0.57)
3 oz =
2.5 ox Laudis 3.5L
+ 0.21 oz ai thiencarbazone
Corvus 2.63SC
isoxaflutole (1.88)
thiencarbazone-methyl (0.75)
5.6 oz =
5.3 oz Balance Flexx 2L
+ 0.52 oz ai thiencarbazone
Degree Xtra 4L
acetochlor (2.69)
atrazine (1.35)
3 qts =
1.9 lbs ai acetochlor
+ 1 lb ai atrazine
Expert 4.88L
s-metolachlor (1.74)
atrazine (2.14)
glyphosate (1.0)
3 qts =
1.36 pts Dual II Magnum 7.64 EC
+ 1.6 lbs ai atrazine
+ 0.56 lbs glyphosate acid
FulTime 4L
acetochlor (2.4)
atrazine (1.6)
3.0 qts =
1.8 lbs ai acetochlor
+ 1.2 lbs ai atrazine
Halex GT 4.38L
s-metolachlor (2.09)
mesotrione (0.209)
glyphosate (2.09)
3.6 pts =
1 pt Dual II Magnum 7.68EC
+ 3 oz Callisto 4L
+ 0.94 lbs glyphosate acid
Harness Xtra 5.6L/
Confidence Xtra 5.6L
acetochlor (3.1)
atrazine (2.5)
2.4 qts =
1.86 lb ai acetochlor
+ 1.5 lbs ai atrazine
Harness Xtra 6L/
Confidence Xtra 6L
acetochlor (4.3)
atrazine (1.7)
2.4 qts =
2.6 lb ai acetochlor
+ 1 lb ai atrazine
Keystone 5.25L
acetochlor (3.0)
atrazine (2.25)
2.6 qts =
1.95 lb ai acetochlor
+ 1.5 lbs ai atrazine
Laddok S-12 5L
bentazon (2.5)
atrazine (2.5)
1.67 pts =
1 pt Basagran 4L
+ 0.5 lb ai atrazine
Lumax EZ 3.67L
s-metolachlor (2.49)
atrazine (0.935)
mesotrione (0.249)
3 qts =
1.94 pts Dual II Magnum 7.68EC
+ 0.7 lb ai atrazine
+ 6 oz Callisto 4L
Lexar EZ 3.7L
s-metolachlor (1.74)
atrazine (1.74)
mesotrione (0.224)
3 qts =
1.35 pts Dual II Magnum 7.68EC
+ 1.3 lbs ai atrazine
+ 5.3 oz Callisto 4L
Marksman/Sterling Plus/
Banvel-K+atrazine 3.2L
dicamba (1.1)
atrazine (2.1)
3.5 pts =
1 pt dicamba 4L
+ 0.9 lb ai atrazine
Shotgun 3.25L
atrazine (2.25)
2,4-D (1.0)
3 pts =
0.85 lb ai atrazine
+ 0.75 pt 2,4-D 4L
Solstice 4L
mesotrione (3.784)
fluthiacet methyl (0.216)
3 oz =
3 oz Callisto 4L
+ 0.7 oz Cadet 0.91L
SureStart/TripleFLEX/TripleFLEX II 4.25L
acetochlor (3.75)
clopyralid (0.38)
flumetsulam (0.12)
1.75 pts =
0.82 lb ai acetochlor
+ 3.5 oz Stinger 3L
+ 0.5 oz Python 80%WDG
Stalwart Xtra 5.5L
atrazine (3.1)
metolachlor (2.4)
2.1 qts =
1.6 lbs ai atrazine
+ 1.3 pts Stalwart C 7.8EC
Volley/Breakfree ATZ 5.25L
atrazine (2.25)
acetochlor (3.0)
2.8 qts =
1.6 lb ai atrazine
+ 2.1 lb ai acetochlor
Verdict 5.57EC
dimethenamid-P (5.0)
saflufenacil (0.57)
13 oz =
11 oz Outlook 6EC
+ 2.6 oz Sharpen 2.85L
WideMatch 1.5L
clopyralid (0.75)
fluroxypyr (0.75)
1.3 pts =
5 oz Stinger 3L
+ 10 oz Starane 1.5L
Zemax 3.67L
mesotrione (0.33)
s-metolachlor (3.34)
2 qts =
5.3 oz Callisto 4L
+ 1.7 pts Dual II Magnum 7.68EC
181
Table 22. Continued
Liquid Premixes for Soybeans
Name
Active Ingredients (lbs active/gallon)
Formulation Equivalents
Authority Assist 4L
sulfentrazone (3.33)
imazethapyr (0.67)
6 oz =
5 oz Spartan 4L
+ 2 oz Pursuit 2L
Boundary/Ledger/ Tailwind
6.5EC
metribuzin (1.25)
s-metolachlor (5.25)
2.1 pts =
0.43 lb metribuzin 75DF
1.4 pts Dual II Magnum
Cheetah Max 3L
glufosinate (2)
fomesafen (1)
34 oz =
29 oz Liberty/Cheetah
+ 18 oz Flexstar
Extreme 2.17L
imazethapyr (0.17)
glyphosate (2)
3 pts =
4 oz Pursuit 2L
+ 0.56 lb glyphosate acid
Flexstar GT
fomesafen (0.66)
glyphosate (2.63)
3.75 pts =
1.3 pts Flexstar
+ 1.2 lbs glyphosate acid
Fusion 2.66EC
fluazifop (2.0)
fenoxaprop (0.66)
8 oz =
8 oz Fusilade DX 2L
+ 8 oz Option II 0.67L
Intimidator 4.81L
s-metolachlor (3.39)
metribuzin (0.75)
fomesafen (0.67)
2.8 pts =
1.24 pts Dual II Magnum 7.64EC
5.6 oz metribuzin 75DF
0.93 pts Reflex 2L
Marvel 3L
fomesafen (2.88)
fluthoacet methyl (0.12)
7.25 oz =
10.4 oz Reflex 2L
0.95 oz Cadet 0.91L
Matador 4.7L
metolachlor (4.01)
metribuzin (0.56)
imazethapyr (0.13)
2 pts =
1 lb ai/A metolachlor
3 oz metribuzin 75DF
2 oz Pursuit 2L
Prefix/Statement
s-metolachlor (4.34)
fomesafen (0.95)
2 pts =
1.1 pts Dual Magnum 7.62EC
+ 0.95 pt Reflex/Dawn 2L
Pummel 5.25L
metolachlor (5)
imazethapyr (0.25)
2 pt =
1.25 lb ai metolachlor
+ 4 oz Pursuit 2L
Sequence 5.25L
glyphosate (2.25)
s-metolachlor (3)
3.5 pts =
1 lb glyphosate acid
+ 1.3 pts Dual II Magnum
Storm 4S
bentazon (2.67)
acifluorfen (1.33)
1.5 pts =
1 pt Basagran 4L
+ 1 pint Blazer 2S
Spartan Advance
sulfentrazone (0.56)
glyphosate acid (3.0)
30 oz =
4.2 oz Spartan 4L
+ 0.7 lbs glyphosate acid
Tackle 4.128SL
imazethapyr (0.128)
glyphosate (3)
32 oz =
2 oz Pursuit 2L
+ 0.75 lb glyphosate acid
Torment 2.5L
fomesafen (2)
imazethapyr (0.5)
1 pt =
16 oz Reflex 2L
+ 4 oz Pursuit 2L
Verdict 5.57EC
dimethenamid-P (5.0)
saflufenacil (0.57)
5 oz =
4.2 oz Outlook 6EC
+ 1 oz Sharpen 2.85L
Vise 5.4L
metolachlor (4.45)
fomesafen (0.95)
2.5 pt =
1.4 lb ai metolachlor
+ 19 oz Reflex 2L
182
Table 22. Continued
Dry Premixes for Corn
Name
Active Ingredients (percentage active)
Formulation Equivalents
Basis Blend 30DF
rimsulfuron (20%)
thifensulfuron (10%)
0.825 oz =
0.16 oz ai rimsulfuron
+ 0.16 oz HarmonySG
Crusher 50DF
rimsufuron (25%)
thifensulfuron-methyl (25%)
1 oz =
0.25 oz ai rimsulfuron
+ 0.5 oz HarmonySG
Distinct 70DF
dicamba (48.6%)
diflufenzopyr (21.4%)
4 oz =
4 oz dicamba 4L
+ 0.9 oz ai diflufenzopyr
Fierce 76WDG
flumioxazin (33.5%)
pyroxasulfone (42.5%)
3 oz =
2 oz Valor SX 51WDG
+ 1.5 oz Zidua 85WDG
Harrow 75DF
rimsulfuron (25%)
thifensulfuron (75%)
0.5 oz =
0.25 oz ai rimsulfuron
+ 0.125 oz Harrass
Hornet 78.5WDG
flumetsulam (18.5%)
clopyralid (60%)
5.0 oz =
1.16 oz Python 80 DG
+ 6.7 oz Stinger 3L
Instigate 45.8%WDG
rimsulfuron (4.17%)
mesotrione (41.67%)
6 oz =
0.35 oz ai rimsulfuron
+ 5 oz Callisto 4L
Northstar 47.4DF
primisulfuron (7.5%)
dicamba (39.9%)
5.0 oz =
0.5 oz Beacon 75DF
+ 4.0 oz dicamba 4L
Prequel 45WDG
rimsulfuron (15%)
isoxaflutole (30%)
1.66 oz =
0.25 oz ai rimsulfuron
+ 0.66 oz isoxaflutole 75WDG
Realm Q 38.75WDG
rimsulfuron (7.5%)
mesotrione (31.25%)
4 oz =
0.3 oz ai rimsulfuron
+ 2.5 oz Callisto 4L
Resolve Q 22.4WDG
rimsulfuron (18.4%)
thifensulfuron (4%)
1.25 oz =
0.23 oz ai rimsulfuron
+ 0.1 oz Harmony SG
Spirit 57DF
prosulfuron (14.2%)
primisulfuron (42.8%)
1.0 oz =
0.25 oz Peak 57DF
+ 0.57 oz Beacon 75DF
Status 56DF
dicamba (40%)
diflufenzopyr (16%)
5 oz =
4 oz dicamba 4L
+ 0.8 oz ai diflufenzopyr
Steadfast Q 37.7WDG
rimsulfuron (12.5%)
nicosulfuron (25.2%)
1.5 oz =
0.19 oz ai rimsulfuron
0.7 oz Accent Q 54.5WDG
Yukon 67.5DF
halosulfuron
dicamba
4 oz =
0.67 oz Permit 75DF
4.4 oz dicamba 4L
183
Table 22. Continued
Dry Premixes for Soybeans
Name
Active Ingredients (percentage active)
Formulation Equivalents
Afforia 50.8 WDG
flumioxazin (40.8%)
tribenuron (5%)
thifensulfuron (5%)
2.5 oz =
2 oz Valor 51WDG
+ 0.25 oz Express 50DF
+ 0.25 oz Harmony 50DF
Authority First 70WDG
sulfentrazone (62.1%)
cloransulam (7.9%)
3 oz =
2.5 oz Spartan 75DF
+ 0.28 oz FirstRate 84DF
Authority MAXX
sulfentrazone (62.1%)
chlorimuron (3.9%)
6 oz =
5 oz Spartan 75DF
0.94 oz Classic 25DF
Authority MTZ 45WDG
sulfentrazone (18%)
metribuzin (27%)
10 oz =
2.4 oz Spartan 75DF
+ 0.17 lb ai metribuzin
Authority XL
sulfentrazone (62.2%)
chlorimuron (7.8%)
4 oz =
3.3 oz Spartan 75DF
+ 1.24 oz Classic 25DF
Canopy/Cloak 75DF
chlorimuron (10.7%)
metribuzin (64.3%)
4 oz =
1.7 oz Classic 25DF
+ 0.16 lb ai metribuzin
Canopy EX/Cloak EX/Fallout 29.5DF
chlorimuron (22.7%)
tribenuron (6.8%)
1.5 oz =
1.4 oz Classic 25DF
+ 0.2 oz Express 50DF
Enlite 47.9 WDG
chlorimuron (2.85%)
flumioxazin (36.21%)
thifensulfuron (8.8%)
3.5 oz =
0.4 oz Classic 25DF
+ 2.5 oz Valor 51WDG
+ 0.62 oz Harmony SG 50DF
Envive 41.3 DG
chlorimuron (9.2%)
thifensulfuron (2.9%)
flumioxazin (29.2%)
3 oz =
1.1 oz Classic 25DF
+ 0.17 oz Harmony SG 50DF
+ 1.7 oz Valor 51WDG
Fierce 76WDG
flumioxazin (33.5%)
pyroxasulfone (42.5%)
3 oz =
2 oz Valor 51WDG
+ 1.5 oz Zidua 85WDG
Fierce XLT 62.4WDG
chlorimuron (6.7%)
flumioxazin (24.6%)
pyroxasulfone (31.2%)
4.5 oz =
1.2 oz Classic 25DF
+ 2.2 oz Valor 51WDG
+ 1.65 oz Zidua 85WDG
Gangster/Surveil
co-pack of FirstRate + Valor
2.4 oz =
2 oz Valor 51WDG
+ 0.4 oz FirstRate 84DF
Latir 55 WDG
flumioxazin (31.5%)
imazethapyr (23.5%)
4.25 oz =
2.6 oz Valor 51WDG
+ 4 oz Pursuit 2L
Optill PRO
Optill PRO WDG component
Co-pack of 68WDG component with Outlook
imazethapyr (50.2%)
saflufenacil (17.8%)
2 oz =
4 oz Pursuit 2L
+ 1.0 oz Sharpen 2.85L
Sonic 70WDG
sulfentrazone (62.1%)
cloransulam (7.9%)
3 oz =
2.5 oz Spartan 75DF
+ 0.28 oz FirstRate 84DF
Synchrony XP 28.4WDG
chlorimuron (21.5%)
thifensufuron (6.9%)
0.75 oz =
0.64 oz Classic 25DF
+ 0.069 oz Harmony GT 75DF
Trivence 61.3%WDG
chlorimuron (3.9%)
flumioxazin (12.8%)
metribuzin (44.6%)
8 oz =
1.2 oz Classic 25DF
+ 2 oz Valor 51WDG
+ 4.75 oz metribuzin 75DF
Valor XLT 40.3WDG
chlorimuron (10.3%)
flumioxazin (30%)
3 oz =
1.23 oz Classic 25DF
+ 1.76 oz Valor 51WDG
184
Table 23. Restrictions on Crop Rotation
This table gives the recrop intervals for the planting of rotational crops following the application of corn and soybean herbicides.
If a herbicide is not listed on the table, there are no restrictions on rotation, provided the crop on which that herbicide is applied is
grown to full maturity and harvested. Refer to the following scale:
NR = No restriction, assuming that the corn or soybean crop is taken to harvest. Where the corn crop fails and soybeans will be
planted within 1 to 2 months of corn herbicide application, consult the label for further precautions.
BA = Conduct a field bioassay prior to rotating to this crop; consult the label for more information. Where products containing
atrazine or Princep are used, see the footnote below for precautions on rotation to soybeans and other crops. Consult herbicide
labels for precautions regarding rotation to seed corn or specialty corn.
Herbicide
Afforia
Anthem/AnthemATZ
Atrazinea
Authority Assist
Authority First
AuthorityMAXX
Authority MTZ
Authority XLl
Autumn
Balance Flexx
Basis/Harrow
Beacon
Bestow - 1 oz/2 oz
Bicep/Cinch ATZa
Boundary/Ledger/Tailwind
Buctril/atrazinea
Callisto/Callisto GT
Callisto Xtra
Canopy/Cloak DFk
Canopy/Cloak EX/Falloutk
Capreno
Cheetah Max
Classic
Command/Commit
Corvus
Crusher 1/1.8 oz
Curtail
Degree
Degree Xtraa
Enlite
Envivek
Experta
Extreme/Tackle
Fierce
Fierce XLT
FirstRate
Flexstar/Rhythm/Flexstar GT
FulTime NXTa
Gangster/Surveil
Halex GT
Harness
Harness Xtraa
Hornet
Impact
Instigate
Intimidator
Keystonea
Laddoka
Latir
Laudis
Lumax/Lexara
Marksmana
Marvel
Matador
Metribuzin
Nicosulfuron
Corn
0.5-1
NR
NR
10
10v
10
10
10
1
NR
NR
14 daysi
NR
NR
4
NR
NR
NR
10
10
NR
10
9n
9
NR
NR
1
NR
NR
9
10
NR
8.5
0.25-1
10
9
10
NR
9
NR
NR
NR
NR
NR
NR
10
NR
NR
8.5
NR
NR
NR
10
8.5
4
NR
Wheat
2
18
14
4
4
4
4
4
4
4
3
3
3/4
15
4.5
15
4
8
4
4
4
4
3
12cd
4
3/4
1
4
4
3
4
15
3
1-2
10
4
4
15
3
4
4
4
4
3
4
4.5
15
9
4
4
4.5/10
10
4
4.5
4
4
Oats
5-10
18
21
18
12
12
18
12
9
18
9
8
9
15
12
15
4
18
30
4
18
4
3
16cd
17
9
1
18
21
10
10
15
18
18
30
18
4
15
9
4
18
21
4
3
9
18
15
9
18
4
10
18
18
18
12
8
Alfalfa
5-10
18
21
12
12
12
12
12
18
10
10
8
10/18
18
4.5
21
10
8
10
10
18
18
12n
16cd
17
10/18
10.5
9
21
12
10
18
4
10
18
9
18
15
12+BA
10
9
21
10.5
9
10
18
15
9
4-12
10
18
18
18
4.5
4
12
Months Before Planting
Clover
Soybeans
5-10
1-7 days
18
18
21
10
40
NR
30+BA
NR
18
NR
18
NR
18
NR
18
9
18
6
10
2-10w
18
8
10/18
1/10
18
10
12
NR
21
10
18
10
18
8
12
NR
12
1.5
18
10
18
NR
12n
NR
16cd
NR
17
9
10/18
1/10
18
10.5i
9
9
21
10
12
NR
18
NR
18
10
40
NR
18
NR
18
NR
18
NR
18
NR
18
10
30+BA
NR
18
10
9
9
21
10
26+BA
10.5
18
9
18
10
18
NR
21
10
9
9
4-12
NR
18
8
18
10
18
10
18
NR
12
NR
12
NR
12
0.5
Tomatoes
6-12+BA
18
21
40
30+BA
15
NRb
12b
18
18
1
18
1
18
12
21
18
18
10b
10b
18
6-18
9bn
9-12f
17
1
18
18
21
9
12b
18
40
18
18b
18
18
18
30+BA
18
8
21
26+BA
18
18
18
21
15
40
10
18
18
4
40
4
10/18h
Popcorn
4
18
NR
18
10v
10
10
10
1
6
10
8
10
NR
12
1
NR
NR
10
10
10
10-12
9n
9
9
10
10.5
NR
NR
9
10
NR
18
18
10
9
12
NR
9
NR
NR
NR
10.5
NR
10
12
NR
NR
18
NR
NR
NR
10
18
4
10
Sweet Corn
4
18
NR
18
10v
18
18
18
1
6
10
8
10
NR
12
1
NR
NR
18
18
10
10
18
9
9
10
10.5
NR
NR
9
18
NR
18
18
18
18
12
NR
18
NR
NR
NR
18/10.5u
NR
10
10
NR
NR
18
NR
NR
NR
18
18
4
10j
185
Table 23. Continued
Herbicide
Northstar
Optill PRO
Peakq
Permit
Princepa
Prefix/Vise/Statement
Prequel
Prowl/Pendimax
Pummel
Pursuit
Python
Raptor
Realm Q
Reflex/Dawn
Resolve Q
Scepter
Shotguna
Solstice
Sonic
Spartan
Spiritp
Stalwart Xtraa
Steadfast
Stinger
SureStart/TripleFLEX/TripleFLEX II
Surpass NXT
Synchronyk (PRE)
Synchronyk (POST)
Torment
Trivencek
Valor/Encompass/Outflank
Valor XLTk
Verdict (>10 oz)
Volley
Volley ATZa
Warrant
WideMatch
Yukon
Zemax
Zidua
Corn
14 daysi
8.5
1
NR
NR
10
NR
NR
9.5
8.5
NR
8.5
NR
10
NR
9.5g
NR
NR
10v
10
1
NR
NR
NR
NR
NR
10
9n
10
10
0.5-1
10
NR
NR
NR
NR
NR
1
NR
NR
Wheat
3
4
NR
2
14
4.5
4
4
4.5
3
4
3
4
4
3
4
14
18
4
4
3
14
4
NR
4
4
4
3
4
4
1
4
4
4
15
4
NR
2
4.5
4
Oats
8
18
NR
2
21
4.5
18
8
18
18
4
9
9
4
9
11
21
18
12
30
3
21
8
NR
9
9
4
3
4
18
12+BA
30
9
21
21
10
NR
2
4.5
18
Alfalfa
8
9
22
9
21
18
10
8
4.5
4
4
3
10
18
10
18
21
18
12
12
18
21
12
10.5
9
9
10
12n
18
10
12+BA
12
9
21
21
9
10.5
9
18
10
Months Before Planting
Clover
Soybeans
18
8
9
0 to 1
22
10
9
9
21
10
18
NR
18
10
8
NR
18
NR
40
NR
26+BA
NR
18
NR
18
10
18
NR
10
10
18
NR
21
10
18
10
30+BA
NR
18
NR
18
10s
21
10
12
0.5
18
10.5
9
9
9
9
12
NR
12n
NR
18
NR
18
NR
12+BA
NR
18
NR
9
9
21
10
21
10
9
NR
BA
10.5
9
9
18
9
18
0
Tomatoes
18
40+BA
22
8
18
18
18
8
40
40
26+BA
9
18
18
18
18
21
18
30+BA
30
10
21
10/18h
18
26+BA
18
10b
9bn
40
12b
12+BA
12b
9
21
21
18
BA
8b
18
18
Popcorn
8
18
10
3
10
12
10
8
9.5
18
9
8.5
10
10
10
18
NR
NR
10v
10
8
NR
10
10.5
9
NR
10
9
10
10
12+BA
10
NR
NR
NR
NR
4
3
NR
0
Sweet Corn
8
18
10
3
10
10
10
8
18
18
18
8.5
10
10
10
18
NR
18
10v
18
8
NR
10
10.5
10.5 - 18
NR
18
18
18
18
4
18
9
10
NR
NR
4
3
NR
0
aRestrictions on rotation following the application of products containing atrazine or Princep will vary, depending on the product. There are a few general guidelines to follow to reduce the potential for
injury to crops planted where these products are used. Plant only corn or sorghum the year (including fall) of application. Where oats, forage legumes, or forage grasses will be planted the following
spring, do not apply more than 0.8 pounds active ingredient. Do not plant sugar beets, tobacco, or vegetable crops the year following application.
bTransplant tomatoes only.
cDo not plant in the fall of year of application or the spring of the following year.
dCover crops may be planted prior to 12 months, but stand reduction may occur. Do not graze or harvest these cover crops for feed or food.
eMoldboard plow to a depth of 12 inches before planting sugar beets in the spring. Recrop interval to sugar beets is extended to 13 months if less than 20 inches of rain falls during the growing season
of application.
f9 months for transplant tomatoes; 12 months for all tomatoes.
gCorn can be planted 9.5 months after application if at least 15 inches of rainfall is received from 2 weeks prior to last application through November 15 of the same year. If this requirement is not met,
plant only a Clearfield corn hybrid the following spring.
hRotation interval for Accent is 10 months where soil pH is 6.5 or less, and 18 months where soil pH is greater than 6.5.
iRefer to Syngenta literature for a list of hybrids that have tolerance to Beacon before planting.
jExcept the sweet corn varieties “merit”, “carnival”, and “sweet success”, for which the minimum rotational interval is 15 months.
kFor rates higher than 1 oz/A (Synchrony), 1.1 oz/A (Canopy EX), 2.2 oz/A (Canopy DF), 6 oz (Trivence), 3.75 oz (Fierce XLT), or 2.5 oz (Envive, Valor XLT), plant only soybeans the following year where
composite soil pH is greater than 7.0 (or greater than 6.8 for Valor XLT and Fierce XLT).
lWhere soil pH is greater than 7.2, rotation intervals increase to at least 18 months for all crops except small grains.
mIf applied after July 1st, do not plant soybeans the season following application.
nIf applied after August 1, extend recrop interval by 2 months.
oIf soil pH is less than 6.2, allow 26 months to rotation of sugarbeets.
pIf soil pH is 7.8 or greater and/or less than 12 inches of rainfall occurs within the first 5 months and/or less than 1.0 inch within the first 4 weeks following application, then only plant corn or small grain
cereals the following spring. STS soybeans can be planted the following spring after a drought if Spirit was used.
rAllow 12 months to rotation of sweet corn if 2-2/3 pt of Command is used.
sDo not plant soybeans the following season if herbicide is applied after June 30.
tSoybeans and tomatoes should not be planted until 18 months after application north of Interstate 70, but can be planted 10 months after application south of Interstate 70. STS soybeans can be
planted the following spring in areas north of Interstate 70.
uOnly certain sweet corn varieties may be grown 10.5 months after application; check herbicide label for those varieties. Otherwise wait 18 months.
vRotation interval extends to 18 months if applied to soil with 1.5% organic matter or less and pH above 7.0.
wHarrow: 10 months. Basis up to 1.25 oz: 60 days south of I70, and 10 months north of I70. Soybeans can be planted 15 days after use of the 0.825 oz Basis rate.
186
Table 24. Glossary of Glyphosate Products, Including Formulations, Surfactant Recommendations,
and Manufacturers
This is a non-inclusive list, and other glyphosate products may be available. Be sure to consult the product label to determine if
that product is approved for postemergence use on Roundup Ready crops.
Active Ingredient
Product
Salt
Acid
Salt
(lb/gallon)
Rate equivalent to
1 quart of Roundup
Original
Surfactant
needed?
Manufacturer
Abundit Extra
IPA
3
4
32 oz
No
Nufarm
Buccaneer
IPA
3
4
32 oz
Yes
Tenkoz, Inc
Buccaneer Plus
IPA
3
4
32 oz
No
Tenkoz, Inc
Clearout 41Plus
IPA
3
4
32 oz
No
Chemical Products Technologies
Cornerstone
IPA
3
4
32 oz
Yes
Agriliance LLC
Cornerstone Plus
IPA
3
4
32 oz
No
Agriliance LLC
Credit Xtreme
IPA+K
4.5
5.83
22 oz
No
Nufarm
Credit 41 Extra
IPA
3
4
32 oz
No
Nufarm
Gly Star Original
IPA
3
4
32 oz
Yes
Albaugh
Gly Star Plus
IPA
3
4
32 oz
No
Albaugh
Gly Star 5
IPA
4
5.4
24 oz
Yes
Albaugh
Gly-4
IPA
3
4
32 oz
Yes
Universal Crop Protection
Gly-4 Plus
IPA
3
4
32 oz
No
Universal Crop Protection
Gly-Flo
IPA
3
4
32 oz
Yes
MicroFlo
Glyphosate Original
IPA
3
4
32 oz
Yes
Griffin
Glyfos
IPA
3
4
32 oz
Yes
Chemi-Nova
Glyfos X-tra
IPA
3
4
32 oz
No
Chemi-Nova
Glyphomax
IPA
3
4
32 oz
Yes
Dow AgroSciences
Glyphomax Plus
IPA
3
4
32 oz
No
Dow AgroSciences
Mirage
IPA
3
4
32 oz
Yes
UAP/Platte
Roundup Original
IPA
3
4
32 oz
Yes
Monsanto
Roundup Original II
IPA
3
4
32 oz
Yes
Monsanto
Roundup PowerMax
K
4.5
5.5
22 oz
No
Monsanto
Roundup WeatherMax
K
4.5
5.5
22 oz
No
Monsanto
Touchdown IQ
DA
3
4
32 oz
No
Syngenta
Salt: IPA = isopropylamine; K = potassium; DA = Diammonium.
Active ingredient: acid = lbs of active glyphosate per gallon; salt = lbs of final formulated product per gallon.
Surfactants: For products that allow or require use of a nonionic surfactant, the typical rate is 0.25% v/v or 1 quart per 100 gallons of spray.
187
Table 25. Glossary of Chemical Names and Manufacturers
Ground
Restricted Water
Use
Advisory
Surface
Water
Advisory
Trade Name
Common Name
Formulations
AAtrex, Atrazine
atrazine
4 lb/gal L, 90% DF, 80% WP
Y
Y
Y
Manufacturer
Syngenta, others
Accurate
metsulfuron
60% DF
N
N
N
Cheminova
Aim
carfentrazone-ethyl
2 lb/gal L
N
N
N
FMC
Accent Q
nicosulfuron + isoxadifen
54.5% WDG
N
N
N
DuPont
Afforia
flumioxazin + tribenuron + thifensulfuron
50.8% WDG
N
N
N
DuPont
Anthem
pyroxasulfone + fluthiacet-methyl
2.15 lb/gal L
N
Y
Y
FMC
Anthem ATZ
pyroxasulfone + atrazine + fluthiacet-methyl
4.5 lb/gal L
Y
Y
Y
FMC
Anthem Flex
pyroxasulfone + carfentrazone
4 lb/gal L
N
Y
Y
FMC
Armezon
topramezone
2.8 lb/gal L
N
N
N
BASF
Arrow
clethodim
2 lb/gal L
N
N
N
ADAMA
Assure II
quizalofop
0.88 lb/gal L
N
N
N
DuPont
Authority Assist
sulfentrazone + imazethapyr
4 lb/gal L
Y
Y
Y
FMC
Authority First
sulfentrazone + cloransulam-methyl
70% WDG
Y
Y
Y
FMC
Authority MAXX
sulfentrazone + chlorimuron-ethyl
66% WDG
N
Y
Y
FMC
Authority MTZ
sulfentrazone + metribuzin
45% WDG
Y
Y
Y
FMC
Authority XL
sulfentrazone + chlorimuron-ethyl
70% DF
Y
Y
Y
FMC
Autumn Super
iodosulfuron-methyl + thiencarbazone
51% WDG
N
Y
Y
Bayer
Axial Star
pinoxaden + fluroxypyr
1.15 lb/gal L
N
N
N
Syngenta
Axial TBC
pinoxaden + florasulam
0.83 lb/gal L
N
N
N
Syngenta
Axial XL
pinoxaden
0.42 lb/gal L
N
N
N
Syngenta
Axiom DF
metribuzin + flufenacet
68% DF
N
Y
Y
Bayer
Balance Flexx
isoxaflutole + cyprosulfamide
2 lb/gal L
Y
Y
Y
Bayer
Banvel
dicamba
4 lb/gal L
N
N
N
MicroFlo
Banvel-K+atrazine
dicamba+atrazine
3.2 lb/gal L
Y
Y
Y
MicroFlo
Banvel SGF
dicamba
2 lb/gal L
N
N
N
MicroFlo
Basagran
bentazon
4 lb/gal L
N
N
N
various
Basis Blend
rimsulfuron + thifensulfuron
30 DF
N
N
N
DuPont
Beacon
primisulfuron
75% DF
N
N
N
Syngenta
Bestow
rimsulfuron
25% DF
N
N
N
Cheminova
Bicep II Magnum
s-metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
Syngenta
Boundary
s-metolachlor + metribuzin
6.5 lb/gal L
N
Y
N
Syngenta
Brash
dicamba + 2,4-D
3.87 lb/gal L
N
N
N
Winfield Solutions
Brawl II
s-metolachlor + safener
7.64 lb/gal L
N
Y
N
Tenkoz
Brawl II ATZ
s-metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
Tenkoz
Breakfree NXT
acetochlor
7 lb/gal L
N
Y
Y
DuPont
Breakfree NXT ATZ
acetochlor + atrazine
5.6 lb/gal L
Y
Y
Y
DuPont
Broadloom
bentazon
4 lb/gal L
N
N
N
Uniphos
Broclean
bromoxynil
2 lb/gal L
N
N
N
UAP-Platte
Brozine
bromoxynil + atrazine
3 lb/gal L
Y
Y
Y
UAP-Platte
Buctril
bromoxynil
2 lb/gal L
N
N
N
Bayer
Buctril/atrazine
bromoxynil + atrazine
3 lb/gal L
Y
Y
Y
Bayer
Butoxone 200
2,4-DB
2 lb/gal L
N
N
N
Cedar
Butyrac 200
2,4-DB
2 lb/gal L
N
N
N
Albaugh
Cadence
acetochlor + safener
6.4 lb/gal L
N
Y
N
UAP Loveland
188
Table 25. Glossary of Chemical Names and Manufacturers—Continued
Ground
Restricted Water
Use
Advisory
Surface
Water
Advisory
Trade Name
Common Name
Formulations
Cadence ATZ
atrazine + acetochlor + safener
5.25 lb/gal L
Y
Y
Y
Manufacturer
UAP Loveland
Cadet
fluthiacet-methyl
0.91 lb/gal L
N
N
N
FMC
Callisto
mesotrione
4 lb/gal L
N
N
Y
Syngenta
Callisto GT
mesotrione + glyphosate
4.18 lb/gal L
Y
Y
Y
Syngenta
Callisto Xtra
mesotrione + atrazine
3.7 lb/gal L
Y
Y
Y
Syngenta
Candor
triclopyr + 2,4-D
3 lb/gal L
N
N
N
Nufarm
Canopy
chlorimuron-ethyl + metribuzin
75% DF
N
Y
N
DuPont
Canopy EX
chlorimuron-ethyl + tribenuron
29.5% DF
N
N
N
DuPont
Capreno
tembotrione + thiencarbazone-methyl
3.45 lb/gal L
N
Y
N
Bayer
Charger Max
s-metolachlor + safener
7.64 lb/gal L
N
Y
N
Winfield Solutions
Charger Max ATZ
s-metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
Agriliance
Chateau
flumioxazin
51% WDG
N
N
N
Valent
Chaparral
metsulfuron + aminopyralid
71.6% WDG
N
Y
N
Dow AgroSciences
Cheetah
glufosinate
2.34 lb/gal L
N
N
N
Nufarm
Cheetah Max
glufosinate + fomesafen
3 lb/gal L
N
N
N
Nufarm
Cimarron Max
metsulfuron methyl + dicamba + 2,4-D
co-pack
N
N
N
DuPont
Cinch
s-metolachlor + safener
7.64 lb/gal L
N
Y
N
DuPont
Cinch ATZ
s-metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
DuPont
Clarity
dicamba
4 lb/gal L
N
N
N
BASF
Clash
dicamba
4 lb/gal L
N
N
N
Nufarm
Classic
chlorimuron-ethyl
25% DF
N
N
N
DuPont
Clean Slate
clopyralid
3 lb/gal L
N
Y
N
Nufarm
Cleansweep D
bromoxynil + fluroxypyr + 2,4-D
4.25 lb/gal L
N
Y
N
Nufarm
Cleansweep M
bromoxynil + fluroxypyr + MCPA
4 lb/gal L
N
Y
N
Nufarm
Cloak
chlorimuron-ethyl + metribuzin
75% DF
N
Y
N
Nufarm
Cloak EX
chlorimuron-ethyl + tribenuron
29.5% DF
N
N
N
Nufarm
Cobra
lactofen
2 lb/gal L
N
N
N
Valent USA
Colt
fluroxypyr + clopyralid
1.5 lb/gal L
N
Y
N
UAP Loveland
Command
clomazone
3 lb/gal L (ME)
N
N
N
FMC, others
Confidence
acetochlor + safener
7 lb/gal L
N
Y
Y
Winfield Solutions
Confidence Xtra 5.6
atrazine + acetochlor + safener
5.6 lb/gal L
Y
Y
Y
Winfield Solutions
Corvus
isoxaflutole + thiencarbazone+ cyprosulfamide
2.63 lb/gal L
Y
Y
Y
Bayer
Crossbow
triclopyr + 2,4-D
3 lb/gal L
N
N
N
Various
Crossroad
triclopyr + 2,4-D
3 lb/gal L
N
N
N
Albaugh
Crusher
rimsulfuron + thifensulfuron-methyl
50% DF
N
N
N
Cheminova
Curio
chlorimuron-ethyl
25% DF
N
N
N
Nufarm
Curtail
clopyralid + 2,4-D
2.38 lb/gal L
N
Y
N
Dow AgroSciences
Dawn
fomesafen
2 lb/gal L
N
N
N
Cheminova
Degree
acetochlor + safener
3.8 lb/gal L
Y
Y
N
Monsanto
Degree Xtra
acetochlor + atrazine + safener
4.04 lb/gal L
Y
Y
Y
Monsanto
Diablo
dicamba
4 lb/gal L
N
N
N
Nufarm
Distinct
dicamba + diflufenzopyr
76.4% DF
N
Y
Y
BASF
Dual II Magnum
s-metolachlor + safener
7.64 lb/gal L, 16% G
N
Y
N
Syngenta
Encompass
flumioxazin
51% WDG
N
N
N
Valent
189
Table 25. Glossary of Chemical Names and Manufacturers—Continued
Ground
Restricted Water
Use
Advisory
Surface
Water
Advisory
Trade Name
Common Name
Formulations
Enlite
flumioxazin + chlorimuron + thifensulfuron
47.8% WDG
N
Y
N
Manufacturer
DuPont
Envive
flumioxazin + chlorimuron + thifensulfuron
41.3% DG
N
Y
N
DuPont
Eptam
EPTC
7 lb/gal L, 10% G
N
N
N
Syngenta
Expert
atrazine + glyphosate + s-metolachlor + safener
4.88 lb/gal L
Y
Y
Y
Syngenta
Express TotalSol
tribenuron methyl
50% DF
N
N
N
DuPont
Extreme
imazethapyr + glyphosate
2.17 lb/gal L
N
N
N
BASF
Fallout
chlorimuron-ethyl + tribenuron
29.5% DF
N
N
N
Agsurf
Fierce
pyroxasulfone + flumioxazin
76% WDG
N
Y
Y
Valent
Fierce XLT
pyroxasulfone + flumioxazin + chlorimuron
62.4% WDG
N
Y
Y
Valent
Finesse
chlorsulfuron + metsulfuron methyl
75% DF
N
N
N
DuPont
FirstRate
cloransulam-methyl
84% DF
N
Y
Y
Dow AgroSciences
Flexstar
fomesafen
1.88 lb/gal L
N
N
N
Syngenta
Flexstar GT
fomesafen + glyphosate
3.29 lb/gal L
N
N
N
Syngenta
Forefront
aminopyralid + 2,4-D
3 lb/gal L
N
N
N
Dow AgroSciences
FulTime NXT
acetochlor + atrazine + safener
4.0 lb/gal L (ME)
Y
Y
Y
Dow AgroSciences
Fusilade DX
fluazifop
2 lb/gal L
N
N
N
Syngenta
Fusion
fluazifop + fenoxaprop
2.66 lb/gal L
N
N
N
Syngenta
Gangster
flumioxazin + cloransulam
co-pack
N
Y
Y
Valent USA
Glory
metribuzin
75% DF
N
Y
N
ADAMA
Gramoxone SL
paraquat
2 lb/gal L
Y
N
N
Syngenta
Halex GT
glyphosate + s-metolachlor + mesotrione
4.38 lb/gal L
N
Y
Y
Syngenta
Halomax
halosulfuron
75% WDG
N
Y
N
Aceto
Harass
thifensulfuron
75% WDG
N
N
N
Cheminova
Harmony Extra TotalSol thifensulfuron + tribenuron methyl
50% DF
N
N
N
DuPont
Harmony SG
thifensulfuron
50% DF
N
N
N
DuPont
Harness
acetochlor + safener
7 lb/gal L, 20% G
N
Y
Y
Monsanto
Harness Xtra 5.6L
acetochlor+atrazine+safener
5.6 lb/gal L
Y
Y
Y
Monsanto
Harrow
rimsulfuron + thifensulfuron
75% DF
N
N
N
Cheminova
Hornet
flumetsulam + clopyralid
78.5% WDG
N
Y
N
Dow AgroSciences
Huskie
pyrasulfotole + bromoxynil
2.47 lb/gal L
N
Y
Y
Bayer
Impact
topramezone
2.8 lb/gal L
N
N
N
AMVAC
Instigate
rimsulfuron + mesotrione
45.8%WDG
N
N
Y
DuPont
Intensity
clethodim
2 lb/gal L
N
N
N
UAP-Platte
Intensity One
clethodim
1 lb/gal L
N
N
N
UAP-Platte
Intimidator
s-metolachlor + metribuzin + fomesafen
4.81 lb/gal L
N
Y
Y
Loveland
Kerb
pronamide
50% WP
N
N
N
Dow AgroSciences
Keystone NXT
atrazine + acetochlor + safener
5.25 lb/gal L
Y
Y
Y
Dow AgroSciences
Laddok S-12
bentazon + atrazine
5 lb/gal L
Y
Y
Y
MicroFlo
Latigo
dicamba + 2,4-D
4.2 lb/gal L
N
N
N
Helena
Latir
flumioxazin + imazethapyr
55% WDG
N
N
N
ADAMA
Laudis
tembotrione
3.5 lb/gal L
N
Y
Y
Bayer
Ledger
s-metolachlor + metribuzin
6.5 lb/gal L
N
Y
N
Tenkoz
Lexar EZ
s-metolachlor+atrazine+mesotrione
3.7 lb/gal L
Y
Y
Y
Syngenta
Liberty 280 SL
glufosinate
2.34 lb/gal L
N
N
N
Bayer
190
Table 25. Glossary of Chemical Names and Manufacturers—Continued
Ground
Restricted Water
Use
Advisory
Trade Name
Common Name
Formulations
Lorox/Linex
linuron
50% DF, 4 lb/gal L
Lumax EZ
s-metolachlor + atrazine + mesotrione
3.67 lb/gal L
Y
Maestro
bromoxynil
2 or 4 lb/gal L
N
Marksman
dicamba + atrazine
3.2 lb/gal L
Y
Marvel
fomesafen + fluthiacet methyl
3 lb/gal L
N
Matador
metolachlor + metribuzin + imazethapyr
4.7 lb/gal L
N
Maverick
sulfosulfuron
75% DF
N
Metribuzin
metribuzin
75% DF
N
Me-Too-Lachlor II
metolachlor + pcr
7.8 lb/gal L
N
Milestone
aminopyralid
2 lb/gal L
N
Moxy
bromoxynil
2 lb/gal L
N
NIC-IT
nicosulfuron
2 lb/gal L
N
Nimble
thifensulfuron + tribenuron
75% WDG
NorthStar
dicamba + primisulfuron
Nuance
tribenuron
Olympus
Optill PRO
N
N
Surface
Water
Advisory
Manufacturer
N
Griffin LLC
Y
Y
Syngenta
N
N
Nufarm
Y
Y
BASF
Y
Y
FMC
Y
Y
Loveland
Y
N
Monsanto
Y
N
ADAMA
Y
Y
Drexel
N
N
Dow AgroSciences
N
N
Riverside
N
N
Cheminova
N
N
N
Cheminova
47.4% WDG
N
N
N
Syngenta
75% WDG
N
N
N
Cheminova
propoxycarbazone-sodium
70% WDG
N
N
N
Bayer
saflufenacil + dimehenamid-p + imazethapyr
co-pack
N
Y
Y
BASF
Oracle
dicamba
4 lb/gal L
N
N
N
Gharda USA
Orion
MCPA + florasulam
2.37 lb/gal L
N
N
N
Syngenta
Outflank
flumioxazin
51% WDG
N
N
N
ADAMA
Outlaw
dicamba + 2,4-D
2.54 lb/gal L
N
N
N
Helena
Outlook
dimethenamid-P
6.0 lb/gal L
N
Y
N
BASF
Panoflex
tribenuron methyl + thifensulfuron-methyl
50% SG
N
N
N
DuPont
Panther
flumioxazin
51% WDG
N
N
N
Nufarm
Parallel
metolachlor + benoxacor
7.8 lb/gal L
N
Y
Y
ADAMA
Parallel PCS
metolachlor
8 lb/gal L
N
Y
Y
ADAMA
Parallel Plus
metolachlor + atrazine
5.5 lb/gal L
Y
Y
Y
ADAMA
Parazone
paraquat
3 lb/gal L
Y
N
N
Makhteshim Agan
PastureGard
triclopyr and fluroxypyr
2 lb/gal L
N
N
N
Dow AgroSciences
Patriot
metsulfuron-methyl
60% WDG
N
N
N
Nufarm
Peak
prosulfuron
57 DF
N
N
N
Syngenta
Pendant
pendimethalin
3.3 lb/gal L
N
N
N
BASF
Pendimax
pendimathalin
3.3 lb/gal L
N
N
N
Dow AgroSciences
Permit
halosulfuron
75% DF
N
Y
N
Gowan
Phoenix
lactofen
2 lb/gal L
N
Y
N
Valent USA
Plateau
imazapic
2 lb/gal L
N
N
N
BASF
Poast
sethoxydim
1.5 lb/gal L
N
N
N
MicroFlo
Poast Plus
sethoxydim + dash
1 lb/gal L
N
N
N
MicroFlo
PowerFlex
pyroxsulam
7.5% DF
N
N
Y
Dow AgroSciences
Prequel
rimsulfuron + isoxaflutole
45% WDG
Y
Y
Y
DuPont
Prefix
fomesafen + s-metolachlor
5.3 lb/gal L
N
Y
N
Syngenta
Princep, Simazine
simazine
4 lb/gal L, 90% DF
N
Y
N
Syngenta, others
Prowl
pendimethalin
3.3 lb/gal L
N
N
N
BASF
Prowl H2O
pendimethalin
3.8 lb/gal L
N
N
N
BASF
191
Table 25. Glossary of Chemical Names and Manufacturers—Continued
Ground
Restricted Water
Use
Advisory
Trade Name
Common Name
Formulations
Pulsar
dicamba + fluroxypyr
1.67 lb/gal L
N
Pummel
metolachlor + imazethapyr
5.25 lb/gal L
N
Pursuit
imazethapyr
2 lb/gal L
N
Python
flumetsulam
80% WDG
N
Rapport BroadSpec
thifensulfuron + tribenuron methyl
50% DF
N
Rapport Tankmix
thifensulfuron + tribenuron methyl
50% DF
N
Raptor
imazamox
1.0 lb/gal L
N
Realm Q
rimsulfuron + mesotrione
38.75%WDG
Reflex
fomesafen
Reglone
diquat dibromide
Relegate
Remedy Ultra
Y
Surface
Water
Advisory
Manufacturer
N
Syngenta
Y
Y
ADAMA
N
N
BASF
Y
N
Dow AgroSciences
N
N
Nufarm
N
N
Nufarm
N
N
BASF
N
N
Y
DuPont
2 lb/gal L
N
N
N
Syngenta
3.73 lb/gal L
N
N
N
Syngenta
triclopyr
4 lb/gal L
N
N
N
Nufarm
triclopyr
4 lb/gal L
N
N
N
Dow AgroSciences
Report Extra
chlorsulfuron + metsulfuron methyl
75% DF
N
N
N
Cheminova
Resolve Q
rimsulfuron + thifensulfuron + isoxadifen
22.4% WDG
N
N
N
DuPont
Resource
flumiclorac-pentyl
0.86 lb/gal L
N
N
N
Valent
Rezult
bentazon + sethoxydim + Dash
Co-Pack
N
N
N
BASF
Rhythm
fomesafen
1.88 lb/gal L
N
N
N
Cheminova
Rifle
dicamba
4 lb/gal L
N
N
N
UAP Loveland
Rifle-D
dicamba + 2,4-D
3.87 lb/gal L
N
N
N
UAP Loveland
Rifle Plus
dicamba + atrazine
3.2 lb/gal L
Y
Y
Y
UAP Loveland
Sandea
halosulfuron
75 DF
N
Y
N
Gowan
Satellite Hydrocap
pendimethalin
3.8 lb/gal L
N
N
N
Uniphos
Scepter
imazaquin
1.5 lb/gal L, 70% DG
N
N
N
BASF
Section
clethodim
2.0 lb/ gal L
N
N
N
Winfield Solutions
Select
clethodim
2.0 lb/ gal L
N
N
N
Valent
Select Max
clethodim
1 lb/gal L
N
N
N
Valent
Sequence
s-metolachlor + glyphosate
5.25 lb/gal L
N
Y
N
Syngenta
Sharpen
saflufenacil
2.85 lb/gal L
N
Y
Y
BASF
Shotgun
atrazine +2,4-D
3.25 lb/gal L
Y
Y
Y
United Ag Products
Sinbar
terbacil
80% WP
N
Y
Y
DuPont
Sonic
sulfentrazone + cloransulam-methyl
70% WDG
N
Y
Y
Dow AgroSciences
Solstice
mesotrione + fluthiacet methyl
4 lb/gal L
N
Y
Y
FMC
Spartan
sulfentrazone
4 lb/gal L
Y
Y
Y
FMC
Spartan Advance
glyphosate + sulfentrazone
4.6 lb/gal L
Y
Y
Y
FMC
Spike
tebuthiuron
20% P
N
Y
N
Dow AgroSciences
Spirit
primisulfuron + prosulfuron
57% DF
N
N
N
Syngenta
Spitfire
2,4-D ester + dicamba
3.57 lb/gal L
N
N
N
Nufarm
Stalwart
metolachlor
8 lb/gal L
N
Y
N
Sipcam Agro USA
Stalwart C
metolachlor + safener
7.8 lb/gal L
N
Y
N
Sipcam Agro USA
Stalwart Xtra
metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
Sipcam Agro USA
Starane
fluroxypyr
1.5 lb/gal L
N
N
N
Dow AgroSciences
Statement
metolachlor + fomesafen
5.24 lb/gal L
N
Y
Y
Cheminovabruss suggestions
Status
dicamba + diflufenzopyr + safener
56% WDG
N
Y
Y
BASF
Steadfast Q
nicosulfuron + rimsulfuron + isoxadifen
27.7% DF
N
N
N
DuPont
192
Table 25. Glossary of Chemical Names and Manufacturers—Continued
Ground
Restricted Water
Use
Advisory
Surface
Water
Advisory
Trade Name
Common Name
Formulations
Manufacturer
Stealth
pendimethalin
3.3 lb/gal L
N
N
N
UAP Loveland
Sterling Blue
dicamba
4 lb/gal L
N
N
N
Winfield Solutions
Sterling Plus
dicamba + atrazine
3.2 lb/gal L
Y
Y
Y
Winfield Solutions
Stinger
clopyralid
3 lb/gal L
N
Y
N
Dow AgroSciences
Storm
bentazon + acifluorfen
4 lb/gal L
N
N
N
United Phosphorus
Stratos
dicamba + atrazine
3.2 lb/gal L
Y
Y
Y
Gharda USA
SureStart
acetochlor + flumetsulam + clopyralid
4.25 lb/gal L
N
Y
Y
Dow AgroSciences
Surpass NXT
acetochlor + safener
6.4 lb/gal L
Y
Y
Y
Dow AgroSciences
Surveil
flumioxazin + cloransulam
co-pack
N
Y
Y
Dow AgroSciences
Synchrony XP
chlorimuron-ethyl + thifensulfuron
28.4% DF
N
N
N
DuPont
Tackle
imazethapyr + glyphosate
4.128 lb/gal L
N
N
N
Cheminova
Tailwind
s-metolachlor + metribuzin
6.5 lb/gal L
N
Y
N
ADAMA
Tapout
clethodim
0.97 lb/gal L
N
N
N
Helena
Targa
quizalifop
0.88 lb/gal L
N
N
N
Gowan
Thunder Master
imazethapyr + glyphosate
2.17 lb/gal L
N
N
N
Albaugh
Torment
fomesafen + imazethapyr
2.5 lb/gal L
N
Y
N
ADAMA
Treaty
thifensulfuron methyl
75% DF
N
M
N
Nufarm
Treaty Extra
thifensulfuron + tribenuron methyl
75% DF
N
N
N
Nufarm
Treflan, Trifluralin
trifluralin
4 lb/gal L, 10% G
N
N
N
Dow AgroSciences, others
TriCor
metribuzin
75% DF
N
Y
N
United Phosphorus
TripleFLEX/TripleFLEX II acetochlor + flumetsulam + clopyralid
4.25 lb/gal L
N
Y
Y
Monsanto
Trivence
chlorimuron + flumioxazin + metribuzin
61.3% WDG
N
Y
Y
DuPont
Trizmet II
metolachlor + atrazine + safener
5.5 lb/gal L
Y
Y
Y
Rosens
Trycera
tricolpyr
2.87 lb/gal L
N
N
N
Helena
Ultra Blazer
acifluorfen
2 lb/gal L
N
N
N
United Phosphorous
Valor
flumioxazin
51% WDG
N
N
N
Valent
Valor XLT
flumioxazin + chlorimuron-ethyl
40.3% WDG
N
N
N
Valent
Velossa
hexazinone
2 lb/gal L
N
Y
N
Helena
Velpar
hexazinone
2 lb/gal L, 90% WP
N
Y
N
DuPont
Verdict
saflufenacil + dimethenamid-P
5.57 lb/gal L
N
Y
Y
BASF
Victory
tribenuron methyl
75% DF
N
N
N
Nufarm
Vida
pyraflufen ethyl
0.208 lb/gal L
N
N
N
Gowan
Vise
metolachlor + fomesafen
5.4 lb/gal L
N
Y
Y
ADAMA
Vision
dicamba
3.8 lb/gal L
N
N
N
Helena
Volley
acetochlor + safener
6.4 lb/gal L
N
Y
Y
Tenkoz
Volley ATZ
acetochlor + atrazine
5.25 lb/gal L
Y
Y
Y
Tenkoz
Volunteer
clethodim
2 lb/gal L
N
N
N
Tenkoz
Warrant
acetochlor
3 lb/gal L
N
Y
Y
Monsanto
Weedmaster
2,4-D + dicamba
3.87 lb/gal L
N
N
N
BASF
WideMatch
clopyralid + fluroxypyr
1.5 lb/gal L
N
Y
N
Dow AgroSciences
Yukon
halosulfuron + dicamba
67.5% WDG
N
Y
N
Gowan
Zemax
mesotrione + s-metolachlor
3.67 lb/gal L
N
Y
Y
Syngenta
Zidua
pyroxasulfone
85% WG
N
Y
Y
BASF
193
Control of Marestail in No-till Soybeans
Marestail Biology
Mark Loux
OSU Weed Science
The Ohio State University
u.osu.edu/osuweeds/
•
•
Bill Johnson
Purdue Extension Weed
Science
www.btny.purdue.edu/
weedscience
Find Herbicide
Labels at:
•
•
cdms.net
agrian.com
greenbook.net
•
Information listed here is based
on research and outreach
Extension programming at Purdue
Marestail (aka horseweed) has two primary
periods of emergence - from late summer into
fall, and from late March through June.
Marestail plants overwinter in the rosette
stage, and remain in this low-growing stage
through late April, followed by stem elongation
(bolting) and growth to an eventual height of 3
to 6 feet. Plants that emerge the previous fall
will start stem elongation earlier than springemerging plants.
Marestail is most easily controlled when in
the seedling or rosette stage, and burndown
herbicides should be applied prior to stem
elongation.
Marestail competes with the soybeans
throughout the growing season, and reduces
crop yield. Marestail matures in late summer
or early fall, and large mature plants can
interfere with soybean harvest.
Marestail plants can produce up to 200,000
seed that are transported by wind, providing
for effective spread of herbicide-resistant
populations.
University, Ohio State University,
and elsewhere. The use of trade
names is for clarity to readers
and does not imply endorsement
of a particular brand nor does
exclusion imply non-approval.
Consult herbicide labels for the
most current information. Copies,
reproductions, or transcriptions of
this document or its information
must bear the statement “Produced
and prepared by Purdue University
or Ohio State University Extension
Weed Science” unless approval is
given by the author.
Soybean yield loss due to marestail
• Herbicide programs must consist of: 1) fall and spring burndown treatments (or
two spring treatments - early spring and at plant) to ensure that the field is free
of marestail at the time of soybean planting, and 2) spring-applied residual (PRE)
herbicides to control marestail for another 6 to 8 weeks after planting.
• Failure to follow these guidelines can result in poor control and reduced soybean
yield. We observed the following soybean yields in a 2010 OSU marestail study:
51 bu/A - the burndown treatment failed to control emerged plants
57 bu/A - the burndown treatment was effective, but there was no residual herbicide
65 bu/A - the burndown was effective and effective residual herbicides were used
194
Herbicide resistance in marestail
Ripley Co. IN
Coshocton Co. OH
• Most populations of marestail in Ohio and Indiana are resistant to glyphosate (group 9), and will not be
controlled by burndown or postemergence applications of glyphosate alone.
• Many marestail populations are now multiple-resistant, to both group 9 and group 2 (ALS-inhibiting - e.g Classic
FirstRate) herbicides Growers should therefore not expect to obtain effective POST control in soybeans with
combinations of glyphosate plus Classic, Synchrony, or FirstRate. Postemergence group 14 herbicides, such as
Flexstar, Cobra, and Cadet, do not control marestail.
Photos: multiple-resistant marestail surviving treatment with (from left to right): glyphosate alone, ALS inhbitor alone, and a
combination of ALS inhibitor and glyphosate
Other impacts of multiple resistance (group 2 + 9)
• Fall-applied Canopy or other chlorimuron- or cloransulam-containing herbicides will not provide residual
control of group 2-resistant marestail into spring, and residual herbicides should largely be reserved for spring
application (at least with regard to marestail - residual control of other weeds can occur).
• Spring-applied residuals should include active rates of non-ALS herbicides - metribuzin, flumioxazin (Valor), or
sulfentrazone (Authority). Low rates of premix products (Canopy, Valor XLT, Sonic, Matador, etc) may not provide
a high enough rate of the non-ALS herbicide.
• In burndown applications, there will be no added effectiveness on emerged marestail from products that
contain chlorimuron or cloransulam, which makes the other herbicides in the mix more important.
LibertyLink soybeans - the most effective marestail control strategy
• LibertyLink soybeans are the most effective tool for management of herbicide-resistant marestail, especially in
fields with high marestail populations.
• Use burndown and residual herbicides as outlined on the next two pages. Apply Liberty/Cheetah POST (29 oz/A)
before marestail plants exceed 6 inches in height. Liberty/Cheetah can be applied POST at rates up to 36 oz/A
for taller plants or plants that have survived previous herbicide treatments, but control may be variable. Follow
with a second POST application as necessary.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex, religion, age, disability, political
beliefs, sexual orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of
program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD).
To file a complaint of discrimination write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410
or call (202) 720-5964 (voice or TDD). USDA is an equal opportunity provider and employer.
10/14
195
Steps for effective management of marestail
1. Use fall herbicide treatments in fields with a history of problems or where marestail seedlings are observed in
fall. The primary goal of a fall treatment is control of emerged plants, and it is not a substitute for a preplant herbicide
treatment the following spring. An application of burndown and residual herbicides is still required closer to the time
of planting in fields that were treated in the fall. For fall applications, we suggest using 2,4-D as the base herbicide
to control marestail, and combining it with one of the following to ensure control of other winter weeds:
•
glyphosate; dicamba (or premix - Brash, WeedMaster, Outlaw, Rifle); Basis/Crusher/Harrow; Express/Nuance; a
low rate of Canopy/Cloak EX or DF; or metribuzin
•
can add Canopy/Cloak to other herbicide combinations to obtain residual control of weeds into spring. However,
do not expect residual from fall-applied Canopy/Cloak to adequately control spring-emerging marestail. We do
not recommend the use of other residual herbicides in the fall due to cost and lack of residual control into spring.
•
can add Basis/Crusher/Harrow, or low rate of metribuzin or Canopy/Cloak to early-fall applications to control
weeds that emerge later in fall, but this should not be needed from mid-October on.
•
Do not overspend on fall treatments. Keep the cost of herbicides in the $6 to $15 range.
2. Apply effective burndown herbicides in spring. Do not plant into existing stands of marestail. Start
weedfree at the time of planting by using one of the following preplant herbicide treatments, applied when marestail
plants are still in the rosette stage. Note - tillage close to time of planting also effectively removes marestail, but
must thoroughly mix the upper few inches of soil and uproot exisiting plants.
- 2,4-D ester plus glyphosate (1.5 lb ae/A)
- Saflufenacil product (Sharpen or Verdict) plus MSO (1% v/v) plus either glyphosate or Liberty
- 2,4-D ester plus glyphosate plus Sharpen or Verdict plus MSO (1% v/v)
- 2,4-D ester plus Gramoxone (3 to 4 pts/A) plus a metribuzin-containing herbicide
- Liberty/Cheetah - 29 to 36 oz/A (addition of metribuzin can improve control)
• The mixture of glyphosate and 2,4-D ester applied in the spring has become more variable for control of marestail
over time, especially in fields that were not treated the previous fall. Plants should be newly emerged and no
larger then the rosette stage at the time of application for best results. In fields where this mixture has previously
failed to provide effective control, add metribuzin and/or Sharpen or use one of the other burndown treatments
listed above.
• Control can be improved by using the highest rate of a 2,4-D ester product that is allowed, based on the interval
between application and soybean planting. For all 2,4-D ester products, rates up to 0.5 lb active ingredient/A must
be applied at least 7 days before planting. Rates between 0.5 and 1.0 lb/A should be applied at least 30 days
before planting, with the the exception of several products (E-99, Salvo, and Weedone 650) that allow 1 lb/A to be
applied 15 days before planting.
• Mixtures of Sharpen with group 14 residual herbicides must be applied 14 days prior to soybean planting on most
soils, and 30 days prior to planting on coarse-textured soils with less than 2% organic matter. Group 14 residual
herbicides include: flumioxazin - Valor/Panther/Encompass/Outflank, Envive/Enlite, Gangster/Surveil, Fierce, Fierce
XLT, Latir, Trivence; sulfentrazone - Authority products, Sonic; and fomesafen - Prefix, Vise, Statement, Torment.
• The addition of dicamba to early spring burndown treatments can improve control or emerged marestail, especially
plants that have overwintered. Dicamba can be more effective than 2,4-D on marestail in the spring, but has more
potential to injure soybeans if the recrop guidelines are not followed. Following dicamba application, soybeans
can be planted 14 to 28 days after an inch of rain has occurred (in total). For example, the Clarity label states the
following - “following application of Clarity and a minimum accumulation of one inch of rain, a waiting interval of 14
days is required for rates of 8 oz/A or less, and 28 days for rates up to 16 oz/A”.
196
Steps for effective management of marestail (continued)
3. Include residual herbicides with the burndown treatment. Add one of the following herbicides or herbicide
combinations to the burndown herbicides, for residual control of marestail until the soybean leaf canopy develops.
- flumioxazin - Valor, Valor XLT, Envive/Enlite, Fierce, Fierce XLT, Gangster/Surveil, Trivence
- sulfentrazone - Authority First, Sonic, Authority XL/Maxx, Authority, Authority Assist
- Metribuzin - Metri DF, Tricor, Glory (at least 8 oz/A, and preferably 10 to 12 oz/A), but do not exceed
recommended rate for soil type
- Add metribuzin to other metribuzin-containing products to bring total metribuzin rate to 0.38 to 0.5 lbs ai/A.
Products here include: Boundary/Ledger, Canopy/Cloak DF, Intimidator, Matador, Authority MTZ
- Control of ALS-resistant populations will be optimized by using rates of premix products that maximize the amount of
the non-ALS component - flumioxazin, sulfentrazone, or metribuzin.
- In OSU research, most effective residual control has occurred with mixtures that contain two non-ALS residual
herbicide components. Examples: mixture of a flumioxazin or sulfentrazone product with metribuzin; mixture of a
metribuzin product with Sharpen (1.5 to 2 oz); Trivence - a premix of flumioxazin, metribuzin, and chlorimuron. Residual
control of marestail with Sharpen occurs primarily at the 1.5 to 2 oz rate, which must be applied 14 to 30 days prior to
planting - see label for specific information.
- Where early spring application is needed due to lack of a treatment the previous fall, it is especially important to
increase herbicide rates and use more complex mixtures (or consider split spring approach).
4. No fall treatment? - consider split-spring applications. Failing to treat fields in the fall can result in a
population of overwintered marestail plants the following spring, which should be controlled early in spring to ensure
effective burndown. Applying all of the burndown and residual herbicide early can result in poor control of plants that
emerge mid-season. An alternative approach is to apply burndown herbicides with some of the residual herbicide in
early spring, and then when soybeans are planted, apply the rest of the residual herbicide. The second application
may require some additional burndown herbicide. Examples here include:
- early spring - glyphosate + 2,4-D + Sonic (2.5 oz/A); at plant - Sonic (2.5 oz) + Gramoxone
- early spring - glyphosate + 2,4-D + metribuzin (4 oz); at plant - Canopy DF (4 oz) + metribuzin (2 oz) + Sharpen (1 oz)
- early spring - glyphosate + 2,4-D + metribuzin (6 oz); 7 days preplant - Envive (4 oz) + 2,4-D ester
5. So this all seems really involved. Can’t I just do it all with one spring preplant treatment?
Maybe - but this is not an approach that has consistently worked well (see photos below). It can be difficult to
accomplish unless the marestail population in the field has been well managed for several years and the population
is generally low. Growers should use their own previous experiences here as guidance, and plan on increasing the
complexity and rates of the herbicide program. Problems with skipping the fall treatment, and applying everything
at once in spring include the following: 1) applying early in spring when plants are small can result in poor control
of plants that are emerging in mid-season if the residual herbicide runs out; and 2) applying closer to planting to
maximize the length of residual often results in less effective control of larger, older marestail plants, especially those
that have overwintered.
Left photo - spring application of glyphosate
+ 2,4-D + residual herbicides (no fall
herbicide treatment)
Right photo - fall application of glyphosate
+ 2,4-D followed by spring application of
glyphosate + 2,4-D + residual herbicides
Fall application = early November
Spring application = April 21 (7 days preplant)
197
WS-51
www.ag.purdue.edu/btny/weedscience
Authors:
Travis Legleiter
Bill Johnson
Palmer Amaranth Biology,
Identification, and Management
Palmer amaranth (Amaranthus palmeri) is
an aggressive, invasive weed native to the
desert regions of the southwest United
States and northern Mexico. It slowly
infiltrated the southeast United States and
has become one of the most significant
weed pests of cotton and soybean producers.
What makes Palmer amaranth such a
problem is that most populations are
resistant to glyphosate and ALS herbicides.
Recently, Palmer amaranth has been
confirmed in Indiana (particularly in the
northwest), Michigan, Ohio, and Illinois.
This means Palmer amaranth could
potentially become a major agronomic
weed in Indiana and the Midwest.
This publication indicates where Palmer
amaranth has been found in Indiana,
describes the plant’s biology, provides ways
to properly identify it, and offers
management strategies.
Palmer Amaranth in Indiana
In Indiana, Palmer amaranth was first
confirmed in the river bottoms of Posey
and Vanderburgh counties. Purdue
University researchers collected Palmer
amaranth seed from one of the river
bottom fields. In greenhouse settings, the
plants from this seed survived applications
of 20 lbs. ae/acre glyphosate (equivalent
of 7 gallons/acre of generic glyphosate).
In the fall of 2012, 51 fields across five
northwest Indiana counties were
confirmed to have Palmer amaranth plant
populations that were not controlled by
management tactics used during that
growing season. The majority of fields
(and the heaviest infestations) were
confirmed in Jasper County. Many of the
observed fields received multiple
applications of glyphosate and attempted
rescue applications of PPO-inhibiting
herbicides (FlexstarВ®, CobraВ®, Ultra
BlazerВ®, etc.).
Researchers believe Palmer amaranth was
introduced to northern Indiana in dairy or
beef manure from animals that were fed
cotton seed hulls or other feed stocks that
came from the South that were
contaminated with Palmer seed. The exact
timing of the initial event is unknown, but
researchers estimate that it happened at
least two or three years ago due to the
severity of infestation in multiple fields.
Farm equipment, specifically combines,
has and will spread Palmer amaranth seed.
Wildlife can also spread the seed into new,
previously uninfested fields. As of fall
2013, Purdue Weed Science confirmed the
presence of Palmer amaranth in 27
Indiana counties.
Photos by Travis Legleiter, except Figures 10 and 11 by Tom Sinnot, Superior Ag Resources.
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Palmer Amaranth Biology, Identification, and Management
Biology and Impact
Emerges for an Extended Period
Palmer amaranth is adaptable and invasive. Evidence of
its adaptability is the success of populations in Michigan
and northern Indiana where average temperatures are
below the preferred temperatures of native Palmer
populations.
Palmer amaranth’s emergence period extends well into
the typical crop season and can, at times, occur after
crop harvest. During the 2013 Indiana growing season,
researchers observed Palmer amaranth emergence from
early May until mid-September. This emergence period
forces producers to manage the weed throughout the
year, unlike other summer annual weeds that are typically managed only through early summer.
The biological distinctions that highlight Palmer
amaranth’s success as a weed are described below.
Adapts Quickly
Amaranth Identification
Palmer amaranth has dioecious reproduction, so
individual plants are either male or female, which forces
outcrossing and genetic diversity. This gives Palmer
amaranth the ability to adapt and quickly spread
herbicide resistance genes when selection pressure is
applied (as when producers repeatedly apply single
mode of action herbicides).
The first, and often critical, step to managing Palmer
amaranth (or any weed) is to scout and identify the
species that exist in each agronomic field. It is easy to
misidentify Palmer amaranth because it looks similar to
three other common amaranth species: redroot pigweed
(Amaranthus retroflexus), smooth pigweed (Amaranthus
hybridus), and common waterhemp (Amaranthus rudis).
The resemblance is especially strong during the seedling
stages of growth.
All too often, the amaranths are all called “pigweed” and
not identified properly by species. The populations in
northwest Indiana were misidentified as waterhemp for
at least the last couple of years and were not managed as
aggressively as the situation demanded.
Produces Lots of Seed
Palmer amaranth is a prolific seed producer. Each plant
can produce at least 100,000 seeds when they compete
with a crop. In noncompetitive scenarios they can
produce nearly a half million seeds.
Distributes Small Seed
Palmer amaranth seeds are rather small and thrive in
no-till or minimum tillage fields. In those situations,
seeds are allowed to stay in their ideal emergence zone:
the top inch of soil. Humans easily transport the small
seeds through grain, seed, or feed contamination; or on
equipment such as combines.
To correctly identify the amaranth species in your field,
note the characteristics described below. While these
characteristics help differentiate the species, remember
that the characteristics also can be variable within a
species even within the same population or field. Due
to this variability, always assess multiple plants within
the field and remember that more than one amaranth
species may exist in the field.
There are several characteristics that differentiate the
three amaranth species:
• Thepresenceofhair
• Leafshape
• Petiolelength
• Apicalmeristemgrowthpattern
• Seedheadstructures
• Leafbladewatermark
• Thepresenceofaleaftiphair
Understanding these characteristics will help producers
correctly identify amaranth species, and then determine
the proper management strategies.
Competes Aggressively
Palmer exhibits aggressive growth and competitiveness
with crops. Under ideal conditions, Palmer amaranth
plants can grow 2 or 3 inches per day. Within two
months, Palmer amaranth plants that emerged on May
29, 2013, were more than 6 feet tall at the Purdue
Palmer amaranth research site. When allowed to compete
throughout the growing season, Palmer amaranth can
create yield losses up to 91 percent in corn (Massinga,
et al.) and up to 79 percent in soybean (Bensch, et al.).
Herbicide Resistance
Palmer populations have evolved resistance to multiple
herbicide modes of action, including ALS inhibitors,
triazines, HPPD inhibitors, dinitroanilines, and
glyphosate. The majority of populations in the South
are ALS-inhibitor- and glyphosate-resistant.
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Palmer Amaranth Biology, Identification, and Management
Presence of Hair
back over the leaf blade to compare the petiole and leaf
blade lengths (Figures 3, 5, and 9).
Only redroot and smooth pigweeds have hairs (pubescence) on their stems and leaf surfaces (Figure 1). The fine
hairs will be most noticeable on the stems towards the
newest growth. Palmer amaranth and common waterhemp do not have hair on any surface. Looking for pubescence is a quick and easy way to differentiate redroot
and smooth pigweeds from the other two amaranths.
This is the most consistent and reliable characteristic
that differentiates Palmer amaranth from common
waterhemp, and it is most evident on the oldest leaves
of plant (lowest on the stem). Leaf shape, leaf
watermark, and leaf tip hair characteristics will help
confirm the identity of Palmer amaranth; however,
these characteristics are much more variable within
species and can make correct identification difficult
and frustrating if used alone.
Figure 1. Redroot and smooth pigweeds have hairs on their
stems and leaf surfaces. These hairs distinguish them from
common waterhemp and Palmer amaranth.
Figure 2. A Palmer amaranth leaf blade with extended petiole.
Leaf Shape
The leaf shapes of amaranths can vary quite a bit within
a single species; however, there are general shapes that
distinguish the species (Figures 2-5).
Common waterhemp leaves are generally long, linear,
and lanceolate.
Palmer amaranth leaves are wider and ovate to
diamond-shaped.
Redroot and smooth pigweed leaves are similar to
Palmer leaves and have a round to ovate shape —
redroot and smooth pigweed leaves, however, have hairs
while Palmer and common waterhemp leaves do not.
Plants that have been sprayed and survived multiple
herbicide applications (especially PPO-inhibitors) can
exhibit variable leaf shapes that may not correctly
represent the species.
Figure 3. A Palmer amaranth petiole bent back over the leaf
blade, demonstrating the length of its petiole.
Figure 4. The linear, lance-shaped leaf blade and short petiole
characteristic of common waterhemp.
Petiole Length
The petiole is the stem-like structure that connects the
leaf blade to the main stem. In Palmer amaranth the
petioles (especially on older leaves) will be as long (or
longer) than the leaf blade itself (Figures 2, 7, and 8).
The petioles of waterhemp, on the other hand, will be
shorter than their long, lance-shaped leaves (Figure 4).
A quick way to determine the petiole length is to simply
pull a leaf and petiole off a plant and bend the petiole
Figure 5. A common waterhemp petiole bent back over the
leaf blade, illustrating the length of its petiole.
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200
Palmer Amaranth Biology, Identification, and Management
Apical Meristem Growth Pattern
Palmer amaranth’s leaf shape and petiole lengths are the
result of the growth pattern of the apical meristem,
which grows to capture as much light as possible. This
results in a rosette-like appearance as you look directly
down from the top of the plant (Figure 6A). This
growth pattern and rosette appearance is often
compared to that of a poinsettia.
The short petioles and long linear leaves of common
waterhemp form a less patterned rosette appearance
when observed from above (Figure 6B).
Figure 7. Young Palmer amaranth seedlings exhibit an extended
petiole on the first true leaves.
A
Figure 8. A Palmer amaranth seedling. Note the extended
petiole on the first true leaves.
B
Figure 9. Note the petiole of this Palmer amaranth seedling is
longer than the leaf blade when bend back over the blade.
Figure 6. These photos show the leaf shapes and apical
meristem growth patterns of Palmer amaranth (A) and
common waterhemp (B). Also note the long petioles of the
Palmer amaranth plant, which extend the lower leaves out
from the shadow of the upper leaves.
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201
Palmer Amaranth Biology, Identification, and Management
Seed Head Structures
Although one should identify weeds before the plants
reach reproductive stage, it can be useful to look at seed
head structures of escaped weeds to help identify the
species.
Palmer amaranth females have a long main terminal
seed head that can reach up to 3 feet long (Figures 10
and 11). Palmer amaranth female seed heads also have
stiff, sharp bracts that give the seed heads a prickly
feeling when touched.
Common waterhemp has multiple branched seed heads
that are similar in length and lack the stiff, prickly bracts.
Figure 10. A Palmer amaranth plant growing in soybean with
multiple terminal seed heads.
Leaf Blade Watermark
The leaves of some (but not all) Palmer amaranth plants
have a white watermark shaped like a chevron or V
(Figure 12). This mark is not present on common
waterhemp, but use this mark only to verify an
identification of Palmer amaranth since not all Palmer
plants will express this characteristic.
Leaf Tip Hair
Figure 11. A Palmer amaranth seed head measuring close to
30 inches long.
You can use the presence or lack of a singular hair in the
leaf tip notch to help distinguish Palmer amaranth and
common waterhemp (Figure 13), although waterhemp
in the western Corn Belt sometimes has the leaf tip hair.
To date, researchers have observed Palmer amaranth
plants in Indiana have this single leaf tip hair, while
common waterhemp plants do not.
It’s important to note that the single hair does not
appear on all Palmer plants or Palmer plant leaves, but
can typically be found on the first two or three true
leaves. Because this characteristic is so variable, use it
only to help confirm the identity of Palmer amaranth
along with the other characteristics, particularly petiole
length.
Figure 12. Some Palmer amaranth leaves have white chevron
or V-shaped watermarks.
Spiny Amaranth: A Common
Misidentification
The presence of stiff, pointy bracts on the female seed
head and leaf axils can lead to confusing Palmer
amaranth with spiny amaranth or spiny pigweed
(Amaranthus spinosus). Spiny amaranth is predominantly
a weed of pastures, livestock holding pens, and feeding
areas; it is rare in agronomic fields. Spiny amaranth has
a bushy growth pattern and exhibits the spiny bracts
throughout its life cycle, whereas Palmer amaranth
exhibits the bracts only at maturity and during
reproductive stages.
Figure 13. Some Palmer amaranth plants have a single hair in
the leaf tip notch.
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Palmer Amaranth Biology, Identification, and Management
In a heavily infested field, this practice can reduce the
Palmer amaranth population up to 50 percent. Deep till
only once, because the buried seed will remain viable up
to five years and will redeposit in the top layer of soil if
you deep till again within that time. Long-term no-till
producers must weigh the weed control benefits of
tillage against the economic and soil-structure benefits
of their no-till system.
Palmer Amaranth Management
Once Palmer amaranth has been properly identified in a
field, the next step is to develop a proactive
management plan. The main management goals should
be to reduce early-season competition with crop plants
and prevent all plants from producing seed and to avoid
spreading the weed to other areas.
Indiana producers who encounter Palmer amaranth should
treat the population as if it is ALS- and glyphosateresistant — that’s because the original transplanted seed
likely came from the South, where the majority of Palmer
populations are resistant to these herbicides. Again, the
most crucial step is to scout fields dilligently and properly
identify Palmer amaranth when it first appears.
Palmer amaranth has only recently been confirmed in
Indiana. Purdue Weed Science has conducted limited
research on its management. The recommendations
provided here are based on the short-term research of
Purdue and recommendations from researchers in the
South and Michigan.
Consider combining cultural practices and herbicide
programs for the most effective Palmer amaranth
management. Palmer is a very aggressive and adaptive
weed, and management programs that rely on a single
mode of action (such as glyphosate as the only post
herbicide) will typically be ineffective at completely
controlling the weed.
Plant a Cereal Rye Cover Crop
A properly managed and crimped cereal rye cover crop
can provide a mulch that will suppress Palmer amaranth
emergence. The majority of research on crimped cereal
rye cover crop suppression on Palmer amaranth has
been combined with deep tillage; hence, the cover crop
is used for its weed suppression capabilities and not the
soil health benefits that cover crop advocates often
promote. No other cover crops have been extensively
studied for use to suppress Palmer amaranth.
Hand Weed
In severe infestations in southern U.S. cotton fields and
some Indiana soybean fields, producers have resorted to
hiring hand weeding crews to remove Palmer amaranth.
It is important to note that weeds should be pulled and
taken out of the field and composted or burned. Plants
that are laid on the soil in the field will reroot and
continue to grow and produce viable seed.
Monitor Ditches and Borders
Cultural Practices
Take care to control Palmer amaranth plants in ditches
and field edges. In fall 2012, Purdue weed scientists
identified Palmer amaranth scattered along multiple
roadside ditches in northwest Indiana. Although these
plants did not compete with field crops, they still help
spread of the population through pollen and seed.
Rotate Crops
Although it’s not a new concept to rotate corn and
soybean, rotating fields to corn allows producers to use
herbicides with additional modes of action that will
control Palmer amaranth. Rotation also helps slow
further resistance issues and preserves current herbicide
tools. In highly infested fields, consider growing corn
for at least two years to maximize Palmer control.
Although, as noted below, exercise caution to prevent
resistance to corn herbicides.
Harvest Heavily Infested Fields Last
Because it is so small, Palmer amaranth seed disperses
and spreads quickly, especially in machinery. Since
combines are one of the largest contributors to the
spread of Palmer amaranth seed, consider harvesting
fields or field sections that have heavy Palmer amaranth
infestations last.
Doing so will help keep the seed in these areas. After
harvest, clean the combine as best as possible to assure
seed will not be spread during the next harvest (this will
be a meticulous and difficult process).
Practice Deep Tillage
Deep tillage (moldboard plow) will bury the small
Palmer amaranth seed below its preferred emergence
depth. Deep tillage will not provide complete control,
but will reduce the number of seeds that can emerge
from the top 1 inch of soil.
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203
Palmer Amaranth Biology, Identification, and Management
Table 1. Herbicides that provide pre-emergence control of Palmer amaranth in corn.
Trade Name(s)
AatrexВ® and othersb
AnthemВ®
Anthem ATZВ®
Balance FlexxВ®
Bicep II MagnumВ®,
Brawl II ATZВ®, and Cinch ATZВ®
Degree XtraВ®, FultimeВ®,
Harness XtraВ®, and KeystoneВ®
CorvusВ®
Dual II MagnumВ® and CinchВ®
FierceВ®
Guardsman MaxВ®
and G-Max LiteВ®
OutlookВ®
Lexar and LumaxВ®
VerdictВ®
ZiduaВ®
Active Ingredient
Site of Action
Site of Action Group #a
atrazine
PSII-inhibitor
pyroxasulfone
Long chain fatty acid-inhibitor
15
fluthiacet-methyl
PPO-inhibitor
14
pyroxasulfone
Long chain fatty acid-inhibitor
15
fluthiacet-methyl
PPO-inhibitor
14
atrazine
PSII-inhibitor
5
isoxaflutole
HPPD-inhibitor
27
atrazine
PSII-inhibitor
5
S-metolachlor
Long chain fatty acid-inhibitor
atrazine
PSII-inhibitor
acetochlor
Long chain fatty acid-inhibitor
15
isoxaflutole
HPPD-inhibitor
27
thiencarbazone
ALS-inhibitor
2
S-metolachlor
Long chain fatty acid-inhibitor
15
pyroxasulfone
Long chain fatty acid-inhibitor
15
flumioxazin
PPO-inhibitor
14
atrazine
PSII-inhibitor
5
dimethenamid-P
Long chain fatty acid-inhibitor
15
dimethenamid-P
Long chain fatty acid-inhibitor
15
atrazine
PSII-Inhibitor
S-metolachlor
Long chain fatty acid-Inhibitor
15
mesotrione
HPPD-Inhibitor
27
saflufenacil
PPO-Inhibitor
14
dimethenamid-P
Long chain fatty acid-Inhibitor
15
pyroxasulfone
Long chain fatty acid-Inhibitor
15
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
Maximum of 2 lbs. ai/A per application and 2.5 lbs. ai/A total for all applications per season.
a
b
7
5
15
5
5
204
Palmer Amaranth Biology, Identification, and Management
Table 2. Corn herbicides that provide post-emergence control of Palmer amaranth.
Trade Name(s)
Active Ingredient
Site of Action
Site of Action Group #a
various
2,4-D
Growth regulator
4
AatrexВ® and othersb
atrazine
PSII-inhibitor
5
CallistoВ®
mesotrione
HPPD-inhibitor
27
BanvelВ®, ClarityВ®, Sterling
BlueВ®, and others
dicamba
Growth regulator
4
atrazine
PSII-inhibitor
5
mesotrione
HPPD-inhibitor
27
tembotrione
HPPD-inhibitor
27
thiencarbazone-methyl
ALS-inhibitor
2
glyphosate
EPSPS-inhibitor
9
S-metolachlor
Long chain fatty acid-inhibitor
atrazine
PSII-inhibitor
5
glyphosate
EPSPS-inhibitor
9
S-metolachlor
Long chain fatty acid-inhibitor
15
mesotrione
HPPD-inhibitor
27
ImpactВ® and ArmezonВ®
topramezone
HPPD-inhibitor
27
LaudisВ®
tembotrione
HPPD-inhibitor
27
LibertyВ® d
glufosinate
Glutamine synthesis inhibitor
10
dicamba
Growth regulator
4
diflufenzopyr
Auxin transport
19
Callisto XtraВ®
CaprenoВ®
ExpertВ® c
Halex GTВ® c
15
StatusВ®
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
Maximum of 2 lbs. ai/A per application and 2.5 lbs. ai/A total for all applications per season.
c
Roundup ReadyВ® corn hybrids only.
d
Liberty LinkВ® corn hybrids only.
a
b
8
205
Palmer Amaranth Biology, Identification, and Management
Herbicide Control in Corn
Herbicide Control in Soybean
There are a number of herbicides available in corn that
effectively control Palmer amaranth and offer alternate
modes of action to incorporate into your herbicide
rotations. In highly infested fields, growing corn for
multiple years can be effective in reducing Palmer
populations. However, when growing corn for multiple
years, take care to not rely heavily on single modes of
action because atrazine- and HPPD-resistant Palmer
amaranth populations have previously been confirmed.
Tables 1 and 2 outline the products available for preemergence and post-emergence use in corn. The tables
also provide the active ingredients and sites of action for
these products. Use these tables (along with knowledge
of other weeds present) to formulate an effective
herbicide program that maximizes the number of sites
of action to delay resistance. Also, be aware that a
maximum application of atrazine is 2 lbs./acre of active
ingredient (ai) and the total of all applications cannot
exceed 2.5 lbs. ai/acre.
In soybean the number of herbicides available to
replace glyphosate for Palmer amaranth control is
limited. Furthermore, the herbicides must be applied
at appropriate weed sizes for consistent control. The
major herbicide limitation occurs with post-emergence
products, so producers must take advantage of the
available burndown and residual products.
Start With a Clean Field
Start with a clean field (either with tillage or an
herbicide burndown) as the first key to successful
Palmer amaranth management in soybean (see Table 3).
Burndown treatments of glyphosate + 2,4-D or
glyphosate + dicamba can be inconsistent on Palmer
larger than four inches. Researchers in Tennessee have
found that gramoxone + metribuzin is the most
consistent burndown, even on large Palmer plants.
Producers may have to consider a two-pass burndown
because gramoxone + metribuzin can be weak on winter
annuals that may also exist in the field.
Table 3. Herbicide products and tank mixes for burndown of Palmer amaranth prior to soybean planting.
Trade Name(s)
or Tank Mix
Active Ingredient
Site of Action
Site of Action Group #a
glyphosate
EPSPS-inhibitor
9
2,4-D
Growth regulator
4
glyphosate
EPSPS-inhibitor
9
dicamba
Growth regulator
4
paraquat
PSI-electron diverter
metribuzin
PSII-inhibitor
LibertyВ® d
glufosinate
Glutamine synthesis inhibitor
10
SharpenВ®/OpTillВ®/OpTill
PROВ®/Veridct +В®
glyphosate, LibertyВ®,
GramaxoneВ® d,e
saflufenacil
PPO-inhibitor
14
glyphosate or glufosinate or
paraquat
EPSPS-inhibitor or glutamine
synthesis inhibitor or
PSI-electron diverter
glyphosate + 2,4-Db,c,d
glyphosate + ClarityВ®
b,c,d
22
GramoxoneВ® + DimetricВ® b
5
9 or 10 or 22
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
Specific trades names are used only for clarification. Multiple glyphosate, 2,4-D, dicamba, and metribuzin products are available for use and are equally effective on Palmer amaranth.
c
Burndown applications containing 2,4-D or dicamba must be applied 7-28 days before planting depending on product and rate. Refer to labels for specific pre-plant intervals
d
Must be applied to Palmer amaranth that is 4 inches tall or shorter to achieve maximum consistent control.
e
Do not apply saflufenacil products with sulfentrazone or flumioxazin as a tank mix or sequential application within 30 days of planting.
a
b
9
206
Palmer Amaranth Biology, Identification, and Management
Table 4. Herbicides that provide pre-emergence control of Palmer amaranth in soybean.
Trade Name(s)
Active Ingredient
Site of Action
Site of Action Group #a
sulfentrazone
PPO-inhibitor
14
various
ALS-inhibitor
2
sulfentrazone
PPO-inhibitor
14
metribuzin
PSII-inhibitor
5
S-metolachlor
Long chain fatty acid-inhibitor
15
metribuzin
PSII-inhibitor
5
chlorimuron
ALS-inhibitor
2
metribuzin
PSII-inhibitor
5
Dual II MagnumВ® and CinchВ®
S-metolachlor
Long chain fatty acid-inhibitor
15
DimetricВ®, TriCorВ®, and others
metribuzin
PSII-inhibitor
5
pyroxasulfone
Long chain fatty acid-inhibitor
15
flumioxazin
PPO-inhibitor
14
fomesafenb
PPO-inhibitor
14
metribuzin
PSII-inhibitor
5
S-metolachlor
Long chain fatty acid-inhibitor
15
alachlor
Long chain fatty acid-inhibitor
15
imazethapyr
ALS-inhibitor
2
metribuzin
PSII-inhibitor
5
S-metolachlor
Long chain fatty acid-inhibitor
15
dimethenamid-P
Long chain fatty acid-inhibitor
15
dimethenamid-P
Long chain fatty acid-inhibitor
15
saflufenacil
PPO-inhibitor
14
imazethapyr
ALS-inhibitor
2
S-metolachlor
Long chain fatty acid-inhibitor
15
fomesafenb
PPO-inhibitor
14
ProwlВ®
pendimethalin
Microtubule inhibitor
3
ValorВ®
flumioxazin
PPO-inhibitor
14
Valor XLTВ®, GangsterВ®,
EnliteВ®, and EnviveВ®
flumioxazin
PPO-inhibitor
14
various
ALS-inhibitor
2
ZiduaВ®
pyroxasulfone
Long chain fatty acid-inhibitor
15
Authority AssistВ®/XLВ®/FirstВ®/
MaxxВ®, and SonicВ®
Authority MTZВ®
BoundaryВ®
CanopyВ®
FierceВ®
IntimidatorВ®
IntrroВ®, LassoВ®, and Micro-TechВ®
MatadorВ®
OutlookВ®
Optill PROВ®
PrefixВ®
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
A total of 0.313 lb./A (north of I-70) or 0.375 lb./A (South of I-70) of fomesafen is allowed to be applied per season.
a
b
10
207
Palmer Amaranth Biology, Identification, and Management
Producers also need to be aware of the planting
restrictions that come with several burndown programs.
Burndowns containing 2,4-D or dicamba require a
pre-plant interval of seven to 28 days, depending on the
product, rate, and for dicamba, when the first
precipitation event occurs after application.
Saflufenacil products (SharpenВ®, OpTillВ®, OpTill PROВ®,
VerdictВ®) for Palmer or winter annual burndown require
a 30-day pre-plant window if the producer will use a
PPO-inhibiting residual (such as flumioxazin or
sulfentrazone).
With these restrictions, it may mean you will have to
make multiple passes over a field in the spring to
effectively burn down existing Palmer, and then apply a
residual herbicide as close to planting as possible.
will reduce the selection pressure of the few postemergence herbicide options.
Apply residual herbicides as close to soybean planting as
possible to maximize product activity in the crop. Fall
or early spring residual herbicide applications provide
very little to no Palmer amaranth control.
Table 4 lists all the soybean products that provide
Palmer amaranth control or suppression — although
the level of suppression varies by product. Purdue Weed
Science research has shown that products with the active
ingredients flumioxazin or sulfentrazone provide the
highest level of control when applied alone; however,
even these herbicides will begin to break down two to
three weeks after application.
Products that contain metribuzin, S-metolachlor,
pyroxasulfone, and dimethenamid-P will provide
marginal suppression of Palmer amaranth; however, these
products will strengthen a residual program when applied
in combination with flumioxazin or sulfentrazone.
Residual Herbicides
Residual herbicides should be the foundation of all
Palmer amaranth herbicide control programs in soybean
(see Table 4). There are a variety of residual soybean
herbicides that will control Palmer amaranth at its
weakest point (emergence) and substantially reduce the
number of plants requiring a post-emergence
application. Using residual herbicides to manage Palmer
Research indicated that the most robust residual
programs combined two or three of these active
ingredients either in tank mixes or premixes. Product
labels may restrict tank mixes; always refer to product
Table 5. Soybean herbicides that provide post-emergence control of Palmer amaranth that is 4 inches tall or less.
Trade Name(s)
Active Ingredient
Site of Action
Site of Action Group #a
S-metolachlor
Long chain fatty acid-inhibitor
15
fomesafenc
PPO-inhibitor
14
fomesafenc
PPO-inhibitor
14
fomesafenc
PPO-inhibitor
14
glyphosate
EPSPS-inhibitor
9
CobraВ® and PhoenixВ®
lactofen
PPO-inhibitor
14
Libertye
glufosinate
Glutamine synthesis inhibitor
10
PrefixВ®b
ReflexВ®/DawnВ® and
FlexstarВ®/RhythmВ®
Flexstar GTВ®
d
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
PrefixВ® has both post-emergence control and residual activity.
c
A total of 0.313 lb./A (North of I-70) or 0.375 lb./A (South of I-70) of fomesafen is allowed per season.
d
Roundup ReadyВ® soybean varieties only.
e
Liberty LinkВ® soybean varieties only.
a
b
11
208
Palmer Amaranth Biology, Identification, and Management
labels before tank mixing products. Remember, many
of these active ingredients and combinations pose crop
injury risk — weigh the potential risk for injury against
the risk of Palmer amaranth escapes.
Post-emergence (Layby) Residuals
Although pre-emergence residuals are the foundation of
Palmer amaranth herbicide programs, these products
will not last the entire season — so Palmer plants will
continue to emerge. Add a residual herbicide (such as
Dual II MagnumВ®, WarrantВ®, or OutlookВ®, or ZiduaВ®)
to your post-emergence application to add residual
activity into the latter parts of the season (see Table 6).
Remember, pre-emergence products do not control
emerged plants and must be tank mixed with one of
the post-emergence options mentioned above.
Post-emergence Herbicide Timing
Post-emergence herbicides in soybean are limited (see
Table 5) to PPO-inhibiting herbicides and LibertyВ®
(Liberty LinkВ® beans only). The timing of these
products is key for effective Palmer amaranth control.
The consistency and overall control of the PPOinhibitors and LibertyВ® is dramatically decreased once
Palmer amaranth plants are taller than 4 inches.
Soybean producers in the South often plow under and
replant soybean once Palmer is taller than 4 inches
without an effective post-emerge herbicide application.
Multiple Applications and Sites of Action (SOA)
The days of one- and two-pass single mode of action
soybean programs are gone. Producers should accept
this fact when managing a Palmer amaranth-infested
field. Producers will have to make multiple applications
before and after planting. Producers should also avoid
applying any single herbicide product or multiple
products with the same mode of action more than twice
in a growing season to avoid conferring resistance to the
few remaining products left to control Palmer amaranth
in soybean.
Tables 3-6 outline the products available for effective
control of Palmer amaranth at burndown, pre-emergence,
and post-emergence, and provide the sites of action of
each product. Use these tables (and the information in
Liberty LinkВ® Considerations
In heavily infested fields consider planting Liberty LinkВ®
soybean because LibertyВ® offers consistent control of
small Palmer amaranth and adds post-emergence
options and another site of action to your rotation
(thus reducing pressures on the PPO-inhibiting
herbicides). Keep a pre-emergence residual as the
foundation of all Palmer amaranth herbicide programs,
even in Liberty LinkВ® soybean.
A Liberty LinkВ® system will also require a layby residual
product to achieve maximum control.
Table 6. Soybean herbicides that can be tank mixed with post-emergence the products listed in Table 5 for additional residual activity in
the crop.
Trade Name(s)
Active Ingredient
Site of Action
Site of Action Group #a
Dual II MagnumВ®
S-metolachlor
Long chain fatty acid-inhibitor
15
OutlookВ®
dimethenamid-P
Long chain fatty acid-inhibitor
15
WarrantВ®
acetochlor
Long chain fatty acid-inhibitor
15
S-metolachlor
Long chain fatty acid-inhibitor
15
glyphosate
EPSPS-inhibitor
pyroxasulfone
Long chain fatty acid-inhibitor
SequenceВ®b
ZiduaВ®c
Classification system using numbers for each specific site of action developed by the Weed Science Society of America.
Roundup ReadyВ® soybean varieties only.
c
Pending label approval for use in soybean — expected in early 2013. Check label to confirm status.
a
b
12
9
15
209
Palmer Amaranth Biology, Identification, and Management
Sources
this publication) to formulate a multiple-pass herbicide
program for Palmer amaranth control that maximizes
the number of herbicide sites of action to delay
development of future resistance.
Bensch, C.N., M.J. Horak, and D. Peterson. 2003.
Inference of redroot pigweed (Amaranthus
retroflexus), Palmer amaranth (A. palmeri), and
common waterhemp (A. rudis) in soybean.
Weed Sci. 51:37-43.
It may be worthwhile to discuss product and program
options with your chemical representative, crop
consultant, or weed science specialist. Pre-plant and
tank mix label restrictions are intricate and these experts
may be able to help you more than can be briefly
discussed in this publication.
Massinga, R.A., R.S. Currie, M.J. Horak, and J. Boyer.
2001. Interference of Palmer amaranth in corn.
Weed Sci. 49:202-208
Reference in this publication to any specific commercial product, process,
or service, or the use of any trade, firm, or corporation name is for general
informational purposes only and does not constitute an endorsement,
recommendation, or certification of any kind by Purdue Extension.
Individuals using such products assume responsibility for their use
in accordance with current directions of the manufacturer.
Financial support for printing and distributing this material was
provided by the United Soybean Board and Indiana Soybean Alliance.
Nov. 2013
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513-558-5111
800-872-5111
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Columbus: 43205
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800-682-7625
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Emergency Contacts
In the event of gross environmental contamination by pesticides, such as a spill or fire, contact:
Ohio Environmental
Protection Agency
24-Hour Emergency Response Group
1800 Watermark Dr.
Columbus 43266
1-800-282-9378 (in Ohio)
614-224-2260 (outside Ohio)
Ohio Department
of Agriculture
Pesticide Regulation Section
8995 East Main Street
Reynoldsburg 43068
1-800-282-1955
8:00 a.m. to 4:30 p.m., Monday through Friday
In event of chemical fire, spill, leak, exposure or accident
on a highway, railway or waterway, contact:
Chemtrec
Washington, D.C.
800-424-9300
24 hours a day; 7 days a week
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