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Dow AgroSciences LLC dowagro.com

9330 Zionsville Road Indianapolis, IN 46268 USA 

308/2E

January 24, 2013

Dr. Neil Hoffman

Science Advisor

USDA/APHIS/BRS

4700 River Road, Unit 98

Riverdale, MD 20737

Diane Sinkowski

Senior Environmental Protection Specialist

USDA/APHIS/BRS

4700 River Road, Unit 147

Riverdale, MD 20737

DAS-68416-4 Soybean and DAS-40278-9 Corn

Dow AgroSciences Petition Numbers 09-349-01p and 09-233-01p

SUPPLEMENTARY DOCUMENTATION IN SUPPORT OF ENVIRONMENTAL ASSESSMENTS

Dear Dr. Hoffman and Ms. Sinkowski:

This letter and attached information is in response to your email of Dec.10, 2012 which included a request for 

information from Dow AgroSciences (DAS) to support your efforts in developing the final Environmental 

Assessment and Response to Comments for DAS-402780-9 corn and DAS-68416-4 soybean. 

The attached information addresses Questions 4, 6, and 7 from Section B. 2,4-D Use.

Herewith, Dow AgroSciences (DAS) is submitting our response to these questions on the enclosed CD.

If you should have any questions or require further information, please contact me at 317-337-3692.

Sincerely,

Gregory L. Orr, Ph.D.

Global Regulatory Leader 

317-337-3692

317-337-4649 (fax)

glorr@dow.com
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DISTRIBUTION PAGE

DED Code: D1C / B1C

bcc: Laura Tagliani, 308/2E

Greg Orr, 308/2E

Heidi Reistad, 308/2E

Federal Action Files, 308/2E unstapled
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Table of Contents

Section C. 2,4-D Use

Question 6 and 7.

Introduction............................................................................................. 4 

Small Grains (Wheat, Barley, Oats, Rye)............................................................5

Tree Nuts, Citrus, Pome Fruit and Stone Fruit......................................................7

Sugarcane................................................................................................10

Rice.......................................................................................................11

Soybean..................................................................................................13

Cotton....................................................................................................14

Fallow and Burndown Uses...........................................................................15

Sorghum.................................................................................................16

Pasture...................................................................................................18

Asparagus................................................................................................20

Corn......................................................................................................21

References...............................................................................................22

Question 4.

Appendix 1...............................................................................................23
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DOW AGROSCIENCES RESPONSE TO USDA-APHIS QUESTIONS 

RECEIVED DECEMBER 10, 2012 REGARDING DAS-40278-9 CORN AND 

DAS-68416-4 SOY.

B. 2,4-D Use. 

6. In crops above where 2, 4-D is used as an herbicide, what other herbicides/management options 

are used with 2, 4-D for weed control? 

7. In the event that 2, 4-D resistant weeds become prevalent in the areas where 2, 4-D is used in 

these crops, what management options are likely to be adopted and what percent increase in 

production costs are expected?

Weed Control Programs and Herbicide Alternatives in Crops Where 2,4-D is Used

Introduction

Weed control programs vary by crop, weed problem, geography, and cropping system (e.g. notill, conventional-till, etc). In those crops where it is labeled, 2,4-D is usually just one part of a 

much broader weed management scheme. Many growers use a combination of weed control 

techniques including cultural, mechanical, and chemical. Practices that establish a dense, 

vigorous crop canopy quickly (e.g. higher seeding rates, optimum soil fertility, proper seedbed 

preparation, seeding depth) provide competition to smother weeds. Planting high-quality, weedfree crop seed is another cultural practice that keeps weed infestations low and easier to manage. 

Tillage can be a useful weed control method in some situations but may not be appropriate where 

soils are susceptible to erosion. In permanent crops, such as trees, vines, and pasture, mowing 

provides a viable means of weed management.

The following sections discuss weed management programs and herbicide options available in

crops where the percentage treated with 2,4-D was 10% or greater as identified in the Screening 

Level Estimates of Agricultural Uses of 2,4-D (March 23, 2012) posted in the EPA docket

(http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0330-0007). While 

there is some discussion of overall weed management for each crop, the focus is on 

postemergence, broadleaf weed control as this is the primary use of 2,4-D in these crops. 

Available information on key broadleaf weeds in these crops is provided in Appendix 1. 

Examples of weed control programs, herbicide information, and costs are provided, but more 

detailed information can be found in various state crop production and weed management guides 

referenced at the end of each section.
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Small Grains (Wheat, Barley, Oats, Rye)

Weed Management Programs and Options: Effective integrated weed management in these 

crops usually involves a combination of cultural, mechanical, and chemical methods. One of the 

most effective means of reducing weed competition is to establish a highly competitive crop. 

This is best accomplished by planting good quality seed into a well-prepared seedbed with good 

fertility and soil moisture. Higher seeding rates can help establish a competitive crop and for 

some weed species delaying planting will allow for destruction of early flushes of weeds via 

tillage or non-selective herbicide application. Mechanical control is limited to preplant or 

postharvest tillage because small grains are either drilled in narrow rows (7-10 inches apart) or 

broadcast seeded. Because weeds that emerge along with the crop are usually the most 

competitive, it is important to plant seed that is certified to be free of weed seed. Crop rotation is 

also a key element of successful weed control as it often reduces the populations of weeds that 

closely mimic the emergence of growth of small grains or are tolerant to herbicides often used in 

these crops. 

Herbicides: A wide range of herbicide products are currently labeled for small grains. Use of 

preplant or preemergence herbicides occurs on a small portion of acres, with the majority being 

treated with one and, sometimes two, postemergence applications. Postemergence graminicides 

are often used to control grass weeds such as wild oats and foxtail. Many different herbicides are 

available for postemergence broadleaf weed control. Dominant modes of action

(http://wssa.net/Weeds/Resistance/WSSA-Mechanism-of-Action.pdf) in small grains are auxins 

(WSSA Group 4) and ALS inhibitors (WSSA Group 2). While 2,4-D is a widely used herbicide 

for these crops, it does not provide acceptable control of grasses or some key broadleaf weeds 

such as kochia and wild buckwheat. Therefore, 2,4-D is usually mixed with other herbicides, 

often those listed in the table below. Only in low production areas such as the far western and 

southern plains of the United States is 2,4-D sometimes used without other herbicides. 

Alternative Herbicides and Management Options: Some isolated cases of auxin resistant weeds 

in small grains have been noted (wild mustard, prickly lettuce, and kochia)

(http://www.weedscience.org/in.asp). Resistance to ALS inhibitors is considered to be 

widespread in some key species, especially kochia. The frequency and severity of auxin 

resistance is relatively low, even in small grains where the use of auxin herbicides has been 

widespread for many years (Mithila et al., 2011). However, even if resistance to 2,4-D should 

become more prevalent, viable alternatives do exist. In small grains 2,4-D is often used for the 

control of summer annual, broadleaf weed species including common lambsquarters, ragweed, 

sunflower, and wild mustard. Table 1., at the end of this section, lists a number of alternative

herbicides and estimated costs. Metsulfuron, for example, can provide control similar to 2,4-D at 

comparable price. The cost of some products, such as a premix of pyrosulfotole and bromoxynil, 
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is higher than 2,4-D but this combination also provides high levels of control of some key 

broadleaves, such as kochia and wild buckwheat, that 2,4-D does not control.

Additionally, some non-chemical control methods can substitute for 2,4-D or enhance other 

control measures. Weeds such as common lambsquarters and common ragweed often germinate 

early in the spring. Tillage just before spring planting can eliminate the major flush of these 

early emerging weeds. A 2009 USDA report on custom tillage rates estimated the cost of 

harrowing at $7.30-8.40 per acre in Kansas.

(http://www.nass.usda.gov/Statistics_by_State/Kansas/Publications/Custom_Rates/index.asp)

Millet

Millet is sometimes grown in the Plains states, often as a short-season rescue crop. Crop culture 

and weed management for millet is usually similar to small grains. The primary herbicides 

labeled for millet are 2,4-D, fluroxypyr, dicamba, carfentrazone, prosulfuron, and mesotrione. 

Mesotrione is a MOA number 27 (HPPD inhibitor) labeled for use preemergence on millet at a 

rate of 0.19 lb ai/A, with an estimated cost of $32/A. 

Table 1. Postemergence broadleaf herbicides currently available for use in small grains.

Herbicide

(common 

name)

MOA1 Crops2 Rate

(lb ae or ai/A)

Cost/Acre Comments

2,4-D amine 4 WW, SW, B, O, R .25-.5 1.15-2.30

MCPA 4 WW, SW, B, O, R .25-.5 1.30-3.20 Similar in spectrum to 2,4-D

Bromoxynil 6 WW, SW, B, O, R .25-.5 8.80-19.05

Carfentrazone 14 WW, SW, B, O, R .008-.031 4.00-15.10

Chlorsulfuron 2 WW, SW, B, O .008-.015 3.60-7.05

Clopyralid 4 WW, SW, B, O .09-.12 16.80-22.15

Dicamba 4 WW, SW, B, O, R .06-.12 2.30-5.25

Pyrasulfotole 27 WW, SW, B, O .028-.038 8.50-11.55 Available only in premix w/ bromoxynil

Florasulam 2 WW, SW, B, O .004 7.20 Available only in premix w/ MCPA

Fluroxypyr 4 WW, SW, B, O .11-.14 10.60-14.15

Thifensulfuron 2 WW, SW, B, O .014-.019 15.95-31.85

Tribenuron 2 WW, SW, B .008-.16 4.70-9.35

Metsulfuron 2 WW, SW, B .004 1.50

Prosulfuron 2 WW, SW, B, O .009-.018 3.65-7.25

Pyraflufen 14 WW, SW, B, O, R .0008-.0016 1.65-3.30 Primarily preplant but can be applied POST

Triasulfuron 2 WW, SW .013-.026 3.00-6.05

Imazamox 2 WW, SW .031-.047 16.25-24.40 Clearfield varieties only 1

WSSA mode of action category

2

WW=winter wheat, SW=spring wheat, B=barley, O=oats, R=rye
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Sources:

Management Guides

http://www.smallgrains.org/DisplayPage.aspx?pageId=Production_Guides__amp__Basic_Practi

ces

http://iwheat.org/book/export/html/2

State Weed Guides

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-small-grains.cfm

http://www.ag.ndsu.edu/weeds/weed-control-guides/nd-weed-control-guide-1

Tree Nuts, Citrus, Pome Fruit and Stone Fruit

Weed Management Programs and Options: Integrated weed management involves the use of 

all available strategies to manage weed populations in a manner that is economically and 

environmentally sound. Such strategies include cultural, mechanical, and chemical methods. 

Perennial tree crop orchards may be infested with a variety of annual and perennial weeds. 

Orchards can benefit from a well-managed vegetative orchard floor cover that is limited to the 

area between the tree rows. This vegetative cover, either via resident vegetation or planted cover

crops, provides a stable surface for machinery, reduce compaction, and improve soil structure 

and water infiltration. Although resident vegetation makes a good cover, it may contain weeds 

that invade the tree row and become difficult to control. On the other hand, properly managed 

cover crops can prevent invasion of the orchard by weeds. It is desirable to keep the area within 

the tree row relatively weed free to reduce competition for water and nutrients as well reduce 

infestations of insects, rodents, and diseases. Tillage is one weed control method for orchards 

but it has significant drawbacks in terms of labor and fuel requirements as well as damage to tree 

roots and increased erosion. Mowing is a more practical mechanical weed control method but 

also suffers from most of the same labor, fuel, and equipment constraints as tillage.

Herbicide Programs: Young trees are more susceptible to weed competition and require higher 

levels of management. Regular preemergence and postemergence treatments during the 

establishment years remove much of the competition by weeds and facilitate irrigation and other 

cultural practices. Treating the tree row with herbicides and maintaining vegetation in the 

orchard middles is common. Dominant modes of action for broadleaf weed control in orchards 

are auxins (WSSA Group 4), ALS inhibitors (WSSA Group 2), EPSPS inhibitors (WSSA Group 

9), Glutamine synthetase inhibitors (WSSA Group 10), PPO inhibitors (WSSA Group 14), Cell 

membrane disruptor (WSSA Group 22). 
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Within the tree row, a combination of preemergence and postemergence herbicides is typically

used. Specific herbicides used vary depending on tree crop, geography, and weed species 

present. Often glyphosate is mixed with a soil residual product such as dichlobenil, diruon, or 

oryzalin. Applications of 2,4-D are usually made in orchards for perennial, broadleaf weeds 

occurring in the tree row or in the vegetative cover between the rows. Herbicide susceptibility, 

treatment guidelines, and weed problems can be found at the web sites listed at the end of this 

section.

Alternative Herbicides and Management Options: While resistance to ALS and EPSPS 

inhibitors are considered to be widespread in some key weed species infesting orchards 

(http://www.weedscience.org/in.asp), resistance to 2,4-D is not common in perennial crop 

producing regions. However, if resistance to 2,4-D were to become more prevalent, viable 

alternatives do exist. 2,4-D is often used for the control of common broadleaf weed species 

including dandelion, field bindweed, and common milkweed. Specific replacement options will 

depend on tree crop, geography, and weed species present. Table 2 below shows several 

possible alternative herbicides and estimated costs. 

Table 2. Postemergence broadleaf herbicides currently available for use in tree crops

Herbicide

(common 

name)

MOA1 Crops2 Rate

(lb ae or ai/A)

Cost/Acre

2,4-D 4 TN,PF,SF 0.95-1.4 4.37-6.44

Glufosinate 10 TN,PF 0.75-1.5 17.95-35.90

Glyphosate 9 TN,PF,SF 1-4 4.15-16.60

Carfentrazone 14 TN,PF,SF 0.016-.031 7.55-15.10

Oxyfluorfen 14 TN,PF,SF 0.25-0.38 7.50-11.40

Paraquat 22 TN,PF,SF 0.3-1.0 5.42-18.05

Rimsulfuron 2 TN,PF,SF 0.0625 14.25

Pyraflufen 14 TN,PF,SF 0.001-0.006 1.65-13.00 1

WSSA mode of action category

2

TN=tree nuts, PF=pome fruit, SF=stone fruit

Additionally, some non-chemical control methods can be used. Mowing or tillage provides a 

valuable tool to the orchardist. A 2009 USDA report on custom rates in Kansas estimates the 

cost of harrowing at $7.30-8.40 per acre and the cost of rotary mowing at $9.33-12.89 per acre 

(http://www.nass.usda.gov/Statistics_by_State/Kansas/Publications/Custom_Rates/index.asp).
9 of 34

Sources:

Tree Nuts

Almonds http://www.ipm.ucdavis.edu/PMG/selectnewpest.almonds.html

Walnuts http://www.ipm.ucdavis.edu/PMG/selectnewpest.walnuts.html

Hazelnuts(filberts) http://pnwhandbooks.org/weed/sites/default/files/chapters/pdf/lorchardsandvineyards.pdf

Pecans http://www.noble.org/global/ag/soils/weed-management-pecans/nf-so-12-04.pdf

Pome Fruit

Apples http://pnwhandbooks.org/weed/sites/default/files/chapters/pdf/lorchardsandvineyards.pdf

http://www.ipmcenters.org/cropprofiles/docs/MIapples.pdf

Pears http://www.ipm.ucdavis.edu/PMG/selectnewpest.pears.html

Stone Fruit

Apricots http://www.ipm.ucdavis.edu/PMG/selectnewpest.apricots.html

Peaches http://www.ipm.ucdavis.edu/PMG/selectnewpest.peach.html

http://www.ent.uga.edu/peach/peachhbk/pdf/weedmanagement.pdf

Nectarines http://www.ipm.ucdavis.edu/PMG/selectnewpest.nectarine.html

Cherries http://www.ipm.ucdavis.edu/PMG/selectnewpest.cherries.html

http://www.ipmcenters.org/pmsp/pdf/mitartcherry.pdf

Plums http://www.ipm.ucdavis.edu/PMG/selectnewpest.plum.html

Prunes http://www.ipm.ucdavis.edu/PMG/selectnewpest.prune.html
10 of 34

Sugarcane

Weed Management Programs and Options: Weed problems in sugarcane can be more difficult 

to manage than in some other crops due to the relatively wide row spacing used, the slow growth 

of the crop during early stages, and abundant moisture and soil fertility used to establish the crop. 

Proper management of weed populations in rotation crops and fallow periods with tillage, 

flooding, and herbicides prior to planting are important to successful weed control in the crop 

itself.

Herbicides: A chemical program for weed control can help growers produce maximum yields of 

sugarcane when combined with sound agronomic practices such as timely cultivation, selection 

of adapted varieties, proper fertilization, and disease and insect control. Controlling grass weeds 

in the monocot crop of sugarcane is the most challenging aspect of weed control in sugarcane. 

Johnsongrass, bermudagrass, naipergrass and itchgrass are troublesome weeds requiring early 

control to avoid potential yield loss due to competition. Typically planted in August or 

September, sugarcane is most susceptible to weed competition during the first eight to ten weeks 

after cane emergence. A split application of herbicide applied at planting followed by a second 

application 60 days later will provide extended control of grasses and winter weeds through the 

early spring. Herbicides used for pre-emergence control include WSSA Group 5 herbicides 

metribuzin, hexazinone and atrazine, WSSA Group 7 diuron, Group 27 herbicide mesotrinone, 

Group 13 herbicide clomazone, Group 14 herbicides sulfentrazone and flumioxazin, Group 3 

herbicides pendimethalin and trifluralin. 

Postemergence weed control options during early growth (Sept.-Nov.) of sugarcane is dependent 

on weeds present. Many postemergence herbicides in sugarcane must be applied as a spray 

directed toward the base of the plants to avoid contact with the upper leaves. Grass control of 

species such as Johnsongrass and Itchgrass may be accomplished with postemergence 

applications of asulam (Group 18) or trifloxysulfuron (Group 2). Bermudagrass may be 

controlled with shielded applications of glyphosate (Group 9). Nutsedge species may be 

controlled with trifloxysulfuron (Group 2) or halosulforon (Group 2). Broadleaf weeds that 

emerge after planting from September to November are commonly controlled with 2,4-D or 

dicamba. In the spring application of residual products atrazine, mesotrione, diuron, metribuzin, 

pendimethalin, trifluralin, flumioxazin or hexazione+diuron for control of broadleaf or broadleaf 

and grass weeds. Layby applications in May or June may be applied broadcast or as a directed 

spray underneath the sugarcane canopy following the last cultivation. Herbicides used in layby 

use include atrazine, sulfentrazone, mesotrione, diuron, metribuzin, pendimethalin, 

sulfentrazone, trifluralin, flumioxazin or hexazinone+diruron. Morningglory can cause a 

significant problems at sugarcane harvest thus a late application prior to harvest of 2,4-D, 
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atrazine, sulfentrazone+metribuzin, mesotrione, dicamba, trifloxysulfuron, paraquat, 

halosulfuron, flumioxazin or sulfentrazone may be applied for control. 

Alternative Herbicides and Management Options: The use of 2,4-D in sugarcane is for the 

control of broadleaf weeds that escape earlier residual herbicides. Several herbicides shown in 

Table 3, such as carfentrazone, flumioxazin, sulfentrazone, halosulfuron and atrazine, provide 

control of key broadleaf species in sugarcane and are viable alternatives to 2,4-D. Glyphosate 

may also be used with shielded sprayer for control of key grass and broadleaf weeds during the 

early season. 

Table 3. Examples of postemergence broadleaf herbicides currently available for use in 

sugarcane.

Herbicide

(common name)

MO

A1

Rate

(lb ae or ai/A)

Cost/Acre Comments

2,4-D 4 .47-1.42 2.30-6.90

Atrazine 5 2.0-4.0 6.40-12.80

Dicamba 4 0.5-0.75 4.10-6.15

Flumioxazin 14 0.1-0.25 18.00-45.00 Post-directed spray

Halosulfuron 2 .03-.06 16.50-33.00 Post-directed spray

Metribuzin 5 .27-.56 6.00-12.00 Combination with sulfentrazone, post-directed

Mesotrione 27 .09 16.00

Paraquat 22 .5-1.0 9.00-18.00 Post-directed spray

Sulfentrazone 14 .19-.25 29.00-38.00 Post-directed spray

Trifloxysulfuron 2 .014-.028 Post-directed spray 1

WSSA mode of action category

Sources:

State Weed Control and Production guides

http://edis.ifas.ufl.edu/wg004

http://www.lsuagcenter.com/en/crops_livestock/crops/sugarcane/weed_management/Louisiana+

Suggested+Chemical+Weed+Management+Guide.htm

Rice

Weed Management Programs and Options: Effective weed control in rice involves cultural, 

mechanical and chemical methods. Planting quality seed of an adapted rice cultivar in a well 

prepared, weed-free seed bed with good fertility will result in the establishment of rice crop with 

early season vigor and competitiveness. A soybean-soybean-rice rotation is recommended over a 
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soybean-rice rotation to allow management of grass weeds in the soybean crops to reduce the 

number of grass weeds in that emerge with the rice crop. Rice is unique in that rice fields are 

permanently flooded after rice is 6-8 inches tall for the primary purpose of weed control. Most 

grass and broadleaf weeds will not germinate and emerge after the flood is established. 

Therefore, early season weed control prior to the establishment of the permanent flood is critical 

in rice production. Grass weed species: barnyardgrass, watergrass, jungle rice, sprangletop 

species and red rice, are critical to control early in the growing season. Broadleaf weeds: 

dayflower, hemp sesbania, jointvetch, smartweed and morningglory species, can be controlled 

before or after flooding without yield or quality loss. 

Herbicides: Pre-emergence herbicides are used primarily to provide early season control of 

grass species such as barnyardgrass, watergrass, sprangletop and broadleaf signalgrass. 

Bolero (thiobencarb, WSSA Group 8) can be applied delayed preemergence or 

postemergence with propanil for control of grass weeds. Pendimethalin (WSSA Group 3) 

can be applied alone (delayed preemergence) for residual grass control or be tank mixed with 

Facet or propanil. Facet (quinclorac, Group 4) is primarily a grass herbicide that also 

controls several important broadleaf weeds. Command (clomazone Group 13) provides 

excellent control of barnyardgrass, sprangletop and broadleaf signal-grass. 2,4-D does not 

control grass weeds. 

Early post-emergence applications are commonly targeted to be applied when barnyardgrass is in 

the 2-3 leaf stage. Propanil (WSSA Group 5) is the most widely used herbicide for 

barnyardgrass control at this timing and has been used for nearly 40 yrs. A residual herbicide 

like pendimethalin, thiobencarb or clomazone may be applied with propanil to provide residual 

control of grass weeds. Other herbicides used in this early timing for grass control include 

quinclorac (WSSA Group 4), penoxsulam (WSSA Group 2), cyhalofop (WSSA Group 1), 

bispyribac (WSSA Group 2) and fenoxyprop (WSSA Group 1). Note that quinclorac is a unique 

Group 4 herbicide that controls grass species. With the exception of the Group 1 herbicides, the 

other herbicides have activity on broadleaf weeds with level of control varying by species and 

herbicide.

Pre-flood herbicide applications target both grasses and broadleaf weeds therefore may contain 

tank mix two herbicide products. Propanil, cyhalofop, quinclorac, penoxsulam, bispyribac or 

fenoxyprop may be used at this timing for grass control and some broadleaf weed control. 

Halosulfuron (WSSA Group 2), bentazon (WSSA Group 6) , acifluorifen (WSSA Group 14), 

triclopyr (WSSA Group 4) or carfentrazone WSSA Group 14) may be applied in tank mix with 

the aforementioned herbicides to broaden the broadleaf control spectrum. 
13 of 34

Post flood herbicide applications may be used to control grass and broadleaf weeds that were not 

controlled prior to establishment of permanent flood or aquatic weeds. Bispyribac, fenoxyprop 

and cyhalofop, penoxsulam, 2,4-D, triclopyr. 

Alternative Herbicides and Management Options: When considering the potential for 2,4-D 

resistant weeds to move from corn or soybean production to rice production, the broadleaf weeds 

of concern will be those that can survive in the flooded rice culture. Those species would 

include the current weeds typically listed as troublesome weeds in rice which include broadleaf 

weeds: hemp sesbania, northern jointvetch, morningglory, smartweed, dayflower, ammania 

species and the aquatic weeds: alligator weed and ducksalad. Table 4 shows several possible 

herbicide alternatives to 2,4-D and estimated costs. The cost of the alternative herbicides are 

higher than 2,4-D but are commonly used currently because of the broader weed control 

spectrum of broadleaf weeds or additional control of grass weeds. Additionally, the use of 2,4-D 

in rice is limited by the narrow application window. Whereas, the other broadleaf herbicide 

products provide a greater application window to control broadleaf weeds. 

Table 4. Examples of postemergence broadleaf herbicides currently available for use in rice.

Herbicide

(common name)

MO

A1

Rate

(lb ae or ai/A)

Cost/Acre Comments

2,4-D 4 1.25-1.5 5.75-7.00

Aciflurofen 14 .125

Bensulfuron 2 .0375-.0625

Bentazon 0.75-1.0 18.00-25.00

Bispyribac 2 .32-.63

Carfentrazone 14 .025-.05 12.00-24.00

Halosulfuron 2 .023-.063 12.50-33.75

Imazosulfuron 2 .15-.3

Penoxsulam 2 .032-.036

Propanil 3.0-6.0

orthosulfamuron 2 .053-.065

Triclopyr 4 .375 11.00

quinclorac 4 .375-.5

Imazamox 2 .031-.047 Clearfield varieties only

Imazethapyr 2 .063-.094 Clearfield varieties only 1

WSSA mode of action category

Sources:

State Weed Control and Production guides

http://www.uaex.edu/Other_Areas/publications/HTML/MP-192.asp

http://www.lsuagcenter.com/en/communications/publications/management_guides/Louisianas+S

uggested+Chemical+Weed+Control+Guide.htm
14 of 34

Soybean

Herbicides and Management Options: Soybean is an annual crop that is either drilled (planted 

in narrow rows, usually 7-10 inches apart) or planted in wide rows (30-40 inches apart). Use of 

no-till crop culture is common in soybeans and herbicides are a key means of weed control. 

Currently, most soybeans in the United States are glyphosate-tolerant and glyphosate is the 

primary herbicide used. Approximately 40-50% of soybean acres receive a preplant or 

preemergence, soil-residual herbicide followed by 1-2 postemergence applications of glyphosate. 

The soil-residual herbicides are often combinations of PPO-inhibitors (WSSA group 14) such as 

flumioxazin or sulfentrazone, with ALS-inhibitors (WSSA group 2) such as cloransulam or 

chlorimuron. Other soil residual products used include active ingredients such as alachlor, 

metolachlor, metribuzin, dimethanamid, or saflufenacil. Almost all of the remaining soybean 

acres are treated only postemergence, usually with glyphosate. Growers will sometimes apply 

postemergence herbicides such as fomesafen or lactofen to control broadleaf weeds not 

controlled with glyphosate or postemergence graminicides such as clethodim or quizalofop to 

control volunteer glyphosate tolerant corn. A small but growing number of acres are planted 

with glufosinate-tolerant soybeans and receive glufosinate applications postemergence rather 

than glyphosate, though the general program remains the same. Because soybeans are naturally 

sensitive to 2,4-D and other auxin herbicides, the current use of 2,4-D for this crop is limited to 

preplant burndown uses. A discussion of this use of 2,4-D as well as alternative herbicides and 

weed control practices are included in a separate section on burndown and fallow.

Sources:

State Weed Control and Production guides

https://ag.purdue.edu/btny/weedscience/Pages/default.aspx

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-soybeans.cfm

Cotton

Weed Management Programs and Options: Cotton is an annual crop this is usually planted in 

wide rows (38-40 inches apart). Use of no-till crop culture is common in cotton and herbicides 

are an important means of weed control. Currently, most cotton varieties in the United States are 

glyphosate-tolerant and glyphosate is a primary herbicide used. Over 60% of cotton acres 

receive a preplant or preemergence, soil-residual herbicide followed by 1-2 postemergence 

herbicide applications, often of glyphosate. The soil-residual herbicides used included a range of 
15 of 34

modes of action. Examples include PSII-inhibitors (WSSA groups 5 and 7) such as prometryn 

and fluometuron, PPO-inhibitors (WSSA group 14) such as fomesafen, ALS-inhibitors (WSSA 

group 2) such as, and mitosis inhibitors (WSSA groups 3 and 15) such as pendimethalin, 

acetochlor and metolachlor . Although a large portion of cotton acres were once treated only 

postemergence with glyphosate, this practice is declining rapidly as glyphosate-resistant weeds 

become more prevalent. A growing number of acres are planted with glufosinate-tolerant cotton 

varieties and receive glufosinate applications postemergence rather than glyphosate, though the 

general program remains the same. Growers will sometimes apply herbicides such as pyrithiobac

to control broadleaf weeds not controlled with glyphosate or postemergence graminicides such as 

clethodim or quizalofop to control grasses. Because cotton is naturally sensitive to 2,4-D and 

other auxin herbicides, the current use of 2,4-D for this crop is limited to preplant burndown 

uses. A discussion of this use of 2,4-D is included in a separate section on burndown and fallow.

Sources:

State Weed Control and Production guides

http://www.ugacotton.com/production-guide/

Fallow and Burndown Uses

Weed Management Programs and Options: One of the primary uses of 2,4-D is in combination 

with other herbicides for control of emerged vegetation either in the fall or spring prior to 

planting. 2,4-D is usually added to burndown applications to improve control of winter annuals, 

perennials, and early emerging summer annual weeds. Examples include shepardspurse, 

marestail, dandelion, common lambsquarters, and giant ragweed. This timing, usually referred 

to as “burndown” can run anywhere from 0-30 days prior to planting depending on crop, 

geography, and product used. Often this is a critical part of an overall weed control program 

since it removes weeds that will be competing with the crop as it emerges. Burndown herbicide 

applications are almost obligatory for no-till crop production systems where tillage is not desired. 

The term “fallow” is usually applied to a longer period of time (often 4-12 months) 

encompassing the summer season. Fallow is mostly used in the arid areas of the Plains and West 

as a means to store soil moisture for a following crop. Given that objective, it is critical to 

control weeds and avoid moisture loss. Tillage can be used as a means of weed control in fallow 

but it is often less desirable due to erosion, time and fuel requirements, and loss of soil moisture 

associated with the tillage operation.

Alternatives to 2,4-D: While 2,4-D provides a means to improve control, it is rarely used alone. 

Most commonly it is used in combination with glyphosate, but can also be used with other 

broad-spectrum, non-selective herbicides such as glufosinate or paraquat. Herbicides with utility 
16 of 34

in burndown and significant foliar activity on broadleaf weeds are listed in Table 5. Depending 

on the crop to be planted and the target weed species, these products can offer an alternative to 

2,4-D in this setting. In several cases these herbicides offer some advantages over 2,4-D such as 

longer residual control. 

Additionally, some non-chemical control methods can substitute for 2,4-D or enhance other 

control measures. Tillage can substitute for herbicide applications to remove weeds before 

planting, except where no-till conditions are desired. USDA reports on custom tillage rates 

estimated the cost of most preplant tillage at $13-15/A.

Table 5. Fallow and burndown herbicides currently available for use in corn, soybeans, cotton and small grains.

Herbicide

(common 

name)

MOA1 Crops2 Rate

(lb ae or ai/A)

Cost/Acre Comments

2,4-D amine 4 C, SB, CT, SG .25-.5 1.15-2.30

Atrazine 5 C 1.0 3.20

Isoxaflutole 6 C .05-.09 14.90-29.80

Chlorimuron 14 SB .033 8.10 Usually in combination with metribuzin ($18/A)

Metribuzin 5 C, SB .5-.75 5.60-8.50 Often at lower rates in combination w/ other herbicides

Dicamba 4 C, SB, CT,SG .25 5.25

Mesotrione 28 C .18-.24 32.00-41.00

Glyphosate 9 C, SB, CT, SG 1.0-1.5 4.00-6.00

Flumioxazin 14 CT, SB .05-.1 9.00-18.00

Sulfentrazone 14 SB .14-.375 23.60-63.00 Obtained at lower cost in premixes

Saflufenacil 14 C, SB, SG .02 5.45

Paraquat 22 C, SB, CT, SG .5-1.0 9.00-18.00

Glufosinate 10 C, CT, SB .53-.66 13.60-16.85

Iodosulfuron 2 C, SB .0019 7.20 Fall only for soybeans, up to 30 d before corn 1

WSSA mode of action category

2

C=corn, SB=soybean, CT=cotton, SG=small grain

Sources:

State Weed Control and Production guides

http://www.ugacotton.com/production-guide/

https://ag.purdue.edu/btny/weedscience/Pages/default.aspx

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-small-grains.cfm

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-corn.cfm

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-soybeans.cfm
17 of 34

Sorghum

Weed Management Options: A variety of weed control options covering chemical, cultural, and 

mechanical methods exist in grain sorghum. Preplant tillage or burndown herbicides remove 

established weeds that would otherwise be difficult to remove after the crop emerges. 

Establishing a vigorous, competitive crop by planting good quality seed into a well-prepared 

seedbed with good fertility and soil moisture is also critical. Crop rotation is another a key 

element of successful weed control since it often reduces the populations of weeds that closely 

mimic the emergence of growth of sorghum or are tolerant to herbicides often used in sorghum.

A number of herbicide products are currently labeled for sorghum and are discussed in the state 

weed control guides referenced at the end of this section. Herbicide programs in sorghum can 

involve a combination of burndown, preemergence, and postemergence herbicides. 

Preemergence applications utilizing atrazine in combination with an acetamide such as 

metolachlor are the mainstay of most chemical weed control programs in sorghum. 

Postemergence herbicides such as 2,4-D, atrazine, dicamba, bentazon, and bromoxynil are used 

to control broadleaf weeds that escape the preemergence treatment. Sometimes these herbicides 

are combined in premixes or tank mixes to broaden the weed spectrum. Common combinations 

include 2,4-D + atrazine, dicamba + atrazine, and bromoxynil + atrazine. 

In-season row cultivation can sometimes be used to control weeds, though it is less common than 

in the past due to increased fuel and labor costs.

Alternative Herbicides and Management Options: Resistance to 2,4-D is not common in most 

grain sorghum areas. However, if resistance to 2,4-D were to become more prevalent, viable 

alternatives do exist. In sorghum, 2,4-D is often used for the control of summer annual, 

broadleaf weed species including common lambsquarters, ragweed, and pigweed. Several 

possible alternative herbicides and estimated costs are shown below in Table 6. Atrazine, for 

example, provides control equivalent to 2,4-D on most weeds, add grass control, and is similar in 

cost. 

Additionally, some non-chemical control methods can substitute for 2,4-D or enhance other 

control measures. Weeds such as common lambsquarters and common ragweed often germinate 

early in the spring. Tillage just before planting can eliminate the major flush of these early 

emerging weeds. A 2009 USDA report on custom tillage rates estimated the cost of harrowing at 

$7.30-8.40 per acre in Kansas. In season row cultivation provides another, non-chemical 

alternative and costs between $7.00 and $8.00 per acre.
18 of 34

Table 6. Postemergence broadleaf herbicides currently available for use in sorghum.

Herbicide

(common 

name)

MOA1 Rate

(lb ae or ai/A)

Cost/Acre Comments

2,4-D amine 4 .25-.5 1.15-2.30

Atrazine 5 1.0 3.20

Bromoxynil 6 .25-.5 8.80-19.05

Carfentrazone 14 .008 4.00

Bentazon 6 0.5-1.0 12.60-25.20 Not a recommended tank mix on label but not prohibited

Dicamba 4 .25 5.25

Prosulfuron 2 .009-.018 3.30-6.60

Halosulfuron 2 .03 12.50 1

WSSA mode of action category

Sources:

State Weed Control and Production guides

https://ag.purdue.edu/btny/weedscience/Pages/default.aspx

http://lubbock.tamu.edu/programs/crops/sorghum/

Pasture

Weed Management Programs and Options: Controlling undesirable plants on pasture and 

rangeland is an important part of an overall management program. Undesirable plants use space, 

moisture, and nutrients that could be put to better use producing forage for grazing animals. 

Poisonous plants are an additional threat to animal health and productivity. Effective 

management of weeds in pasture and rangeland situations usually involves a combination of 

cultural, mechanical, and chemical methods. A primary means of controlling weeds in these 

settings is proper management of desirable forage grasses and legumes. Pastures that are overgrazed provide opportunities for establishment and proliferation of weeds. Low soil fertility in 

pastures also contributes to weed problems due to poor competitive growth of forages. In some 

cases, degraded pastures can be renovated through reseeding or inter-seeding to improve forage 

growth and competition. For some situations burning or mowing can stimulate forage grass 

growth and suppress weeds. Combined with well-timed herbicide applications, management of 

forage growth through these various means can effectively manage weeds and promote optimum 

forage productivity.

Other methods that have a definite place in range management are: chemical, roto-beating, 

plowing, disking, railing, chaining, burning, reseeding, and changes in grazing schedules. There 

are specific sites and reasons for use of the controls listed. Each is effective if used properly. 

Herbicides: Many of the most problematic weeds in pastures are brush and perennial 

broadleaves. Therefore, systemic herbicides with good translocation to roots and other 
19 of 34

reproductive plant parts are highly desirable. Auxin herbicides (WSSA Group 4) tend to 

dominate these markets because of these characteristics, but ALS inhibitors (WSSA Group 2), 

PSII inhibitors (WSSA Group 7), PPO inhibitors (WSSA Group 14) and cell membrane 

disruptors (WSSA Group 22). 2,4-D is widely used on pasture and rangeland but does not 

provide acceptable control of grasses and some key broadleaf weeds. Therefore, it is often 

mixed with other herbicides. In some cases spot spraying of weed patches with small ground 

equipment or hand sprayers is effective and economical. 

A wide range of herbicide products are currently labeled for pastures and rangeland Some cases 

of auxin resistant weeds have been noted (http://www.weedscience.org/in.asp), though these 

populations are often isolated. 

Alternative Herbicides and Management Options: The frequency and severity of auxin 

resistance is relatively low, in pastures even though the use of auxin herbicides has been 

widespread for many years (Mithila et al., 2011). However, even if resistance to 2,4-D should 

become more prevalent, viable alternatives do exist. Table 7 below shows several possible 

herbicide alternatives and estimated costs. In the case of metsulfuron, for example, control 

similar to 2,4-D can be provided for the same cost or less.

Table 7. Postemergence broadleaf herbicides commonly used in pastures and rangeland.

Herbicide

(common 

name)

MOA1 Rate

(lb ae or ai/A)

Cost/Acre

2,4-D 4 1-2 5.00-10.00

Aminopyralid 4 0.06-0.11 16.12-32.11

Metsulfuron 2 0.06-0.6 1.35-13.53

Carfentrazone 14 0.015-0.031 1.70-3.40

Chlorsulfuron 2 0.19-1.0 5.00-25.08

Clopyralid 4 0.14-0.375 13.33-35.70

Dicamba 4 0.5-1.5 9.99-29.97

Fluroxypyr 4 0.6-0.72 20.63-24.76

Picloram 4 0.25 7.50

Triclopyr 4 0.25 3.75

Hexazinone 5 0.67-1.12 25.54-42.69

Paraquat 22 0.25-0.5 3.98-7.96

Tebuthiuron 7 0.4 16.00 1

WSSA mode of action category

Additionally, some non-chemical control methods can be used. Mowing provides a valuable tool 

for weed management. A 2012 University of Nebraska report 

(http://cropwatch.unl.edu/web/economics/customrates) on custom rates in Nebraska estimates 
20 of 34

the cost of rotary mowing at $13.95 per acre. A 2008 NASS publication provides land 

preparation and brush control costs from Texas.

(http://www.nass.usda.gov/Statistics_by_State/Texas/Publications/Custom_Rates_Statistics/cus0

8_26.pdf)

Sources:

http://www.caes.uga.edu/commodities/fieldcrops/forages/pests/WeedPerGrass.pdf

http://forages.tamu.edu/PDF/B-5038.pdf

Asparagus

Herbicides and Management Options: 2,4-D is an important tool in the production of 

asparagus. It is particularly useful in controlling dandelion, plantain and field bindweed. It does 

not provide acceptable control of grasses

The post emergence modes of action in asparagus are auxins (WSSA Group 4), ALS inhibitors 

(WSSA Group 2) and Photosynthesis inhibitors (WSSA Group 7). Auxin resistant weeds are not 

known to be an issue in asparagus production. Resistance to ALS inhibitors is considered to be 

widespread in some key species (http://www.weedscience.org/in.asp).

Alternative Herbicides and Management Options: The frequency and severity of auxin 

resistance is relatively low (Mithila et al., 2011). However, even if resistance to 2,4-D should 

become more prevalent, viable herbicide alternatives do exist as shown in Table 8 below. 

Table 8. Postemergence broadleaf herbicides available for use in asparagus. 

Herbicide

(common 

name)

MOA1 Rate

(lb ae or ai/A)

Cost/Acre

2,4-D 4 1.5-2.0 7.50-10.00

Clopyralid 4 .19-.25 14.00-18.00

Dicamba 4 .25-.5 5.00-10.00

Halosulfuron 2 .03 12.50

Linuron 7 1.0-2.0 NA at this time 1

WSSA mode of action category
21 of 34

Sources:

http://veginfo.msu.edu/bulletins/E433/index.cfm?crop=101

Corn

Herbicides and Weed Management Options: Corn is an annual crop that is usually grown in 

rows 30-40 inches apart. A range of tillage regimes are used to grow corn ranging from no-till to 

conventional tillage. Preplant tillage or burndown herbicides remove established weeds that 

would otherwise be difficult to remove after the crop emerges. Establishing a vigorous, 

competitive crop by planting good quality seed into a well-prepared seedbed with good fertility 

and soil moisture is also critical. Crop rotation is another a key element of successful weed 

control since it often reduces the populations of weeds that closely mimic the emergence of 

growth of corn or are tolerant to herbicides often used in corn. 

A wide range of herbicide products are currently labeled for corn. Herbicide programs in corn 

often involve a combination of burndown, preemergence, and postemergence herbicides. 

Preemergence applications utilizing atrazine in combination with an acetamide such as 

acetochlor are the mainstay of most chemical weed control programs in many areas. 

Postemergence herbicides such as atrazine, dicamba, bentazon, and bromoxynil are used to 

control broadleaf weeds that escape the preemergence treatment. Since introduction of 

glyphosate-tolerant hybrids in the late 1990’s, glyphosate has become one of the most common 

postemergence products in corn. Sometimes these herbicides are combined in premixes or tank 

mixes to broaden the weed spectrum. While 2,4-D is registered for postemergence use in corn, 

it’s use is limited due to a restricted window of application and crop injury concerns. Therefore, 

it is most often used in burndown applications rather than postemergence. The section of this 

document on weed control in burndown and fallow discusses viable herbicide alternatives to 2,4-

D as it applies to burndown in corn. 

In-season row cultivation can sometimes be used to control weeds, though it is less common than 

in the past due to increased fuel and labor costs.

Sources:

State Weed Control and Production guides

https://ag.purdue.edu/btny/weedscience/Pages/default.aspx

http://www.sdstate.edu/ps/extension/weed-mgmt/weed-mgmt-corn.cfm
22 of 34

General References

Herbicide Handbook, Ninth Edition. 2007. Weed Science Society of America.

International Survey of Herbicide Resistant Weeds. www.weedscience.org.

Mithila, J., J.C. Hall, W.G. Johnson, K.B. Kelley, D.E.Riechers. 2011. Development of 

resistance to auxinic herbicides: Historical perspectives, mechanisms of resistance, and 

implications for broadleaf weed management in agronomic crops. Weed Science 59:445–457.
23 of 34

Appendix 1.

B. 2,4-D Use

4. What are the major weeds in each of these crops? What are the major weeds in corn and 

soybean? Please provide this information on a state or regional basis

Major Weeds by Crop: This data set can be found in the Excel files; ‘Crop Weed Charts’, 

‘Fallow Weed Charts’ and ‘RP Weed Charts’ that accompany this submission on CD. This data 

was compiled from university extension publications and university weed guides and contains a 

broad list of weeds that may occur in the selected crop whereas the following section focuses on 

major broadleaf weeds.

Major Broadleaf Weeds by Crop: The crops were selected based on 10% or higher of the crop

being treated with 2,4-D as shown in Table 1: “Screening Level Estimates of Agricultural Uses 

of 2,4-D”. The charts below show the top 15 broadleaf weeds based on treatment acres from 

highest to lowest in each of the selected crop groups at the national level based on data from

third party proprietary survey data of U.S. farmers. Pecans were split from almonds and walnuts 

as they are grown in a different area of the United States under different management practices 

and have different weed issues. Regional information is shown where sample size was deemed 

sufficient.

National Data

NUT CROPS – walnuts, almonds PECANS

MALLOW, COMMON

FLEABANE

FILAREE

MARESTAIL

FLEABANE, HAIRY

CHICKWEED

SHEPHERD'S-PURSE

PIGWEED, REDROOT

SOWTHISTLE

MORNINGGLORY

SPURGE

BINDWEED, FIELD

GROUNDSEL

PURSLANE

ROCKET, LONDON

PIGWEED, REDROOT

MUSTARD, WILD

KOCHIA

PURSLANE

RAGWEED

THISTLE, RUSSIAN

GERANIUM, DOVEFOOT

MORNINGGLORY

FILAREE

NIGHTSHADE, PURPLE

THISTLE

LAMBSQUARTERS

PIGWEED, TUMBLE

MARESTAIL

SIDA, PRICKLY
24 of 34

CITRUS – oranges, grapefruit STONE FRUIT – cherries, 

peaches, apricots, plumes, 

prunes

POME FRUIT – apples, pears

SPANISHNEEDLES

PIGWEED, REDROOT

GROUNDSEL

ST. JOHNSWORT

EVENINGPRIMROSE

MARESTAIL

FLEABANE

SPURGE

FLEABANE, HAIRY

RAGWEED

PANICUM

MILKWEED

BALSAMAPPLE

MALLOW, COMMON

PUSLEY, FLORIDA

MALLOW, COMMON

PIGWEED, REDROOT

FLEABANE

FILAREE

MARESTAIL

LAMBSQUARTERS

CHICKWEED

DANDELION

FLEABANE, HAIRY

MUSTARD, WILD

HENBIT

CLOVER

BUTTERCUP

MORNINGGLORY

SPURGE

LAMBSQUARTERS

PIGWEED, REDROOT

MALLOW, COMMON

MORNINGGLORY

DANDELION

MARESTAIL

FLEABANE

GROUNDSEL

CHICKWEED

THISTLE, CANADA

KOCHIA

BUTTONWEED

THISTLE

FILAREE

RAGWEED

SPRING CEREALS – spring wheat, barley, oats WINTER WHEAT

KOCHIA

THISTLE, CANADA

PIGWEED, REDROOT

MUSTARD, WILD

BUCKWHEAT, WILD

LAMBSQUARTERS

THISTLE, RUSSIAN

LETTUCE, PRICKLY

THISTLE

RAGWEED

BINDWEED, FIELD

MUSTARD, YELLOW

MUSTARD, TUMBLE

TANSYMUSTARD

DANDELION

KOCHIA

PIGWEED, REDROOT

THISTLE, RUSSIAN

MUSTARD, WILD

BINDWEED, FIELD

BUCKWHEAT, WILD

HENBIT

LAMBSQUARTERS

SUNFLOWER

MUSTARD, YELLOW

PIGWEED, TUMBLE

GARLIC, WILD

THISTLE

LETTUCE, PRICKLY

CHICKWEED

SORGHUM FALLOW

PIGWEED, REDROOT

KOCHIA

BINDWEED, FIELD

THISTLE, RUSSIAN

PUNCTUREVINE

DEVIL'S-CLAW

AMARANTH, PALMER'S

MARESTAIL

VELVETLEAF

SUNFLOWER

COCKLEBUR

MORNINGGLORY

SUNFLOWER, VOLUNTEER

RAGWEED

TANSYMUSTARD

KOCHIA

PIGWEED, REDROOT

THISTLE, RUSSIAN

THISTLE

BINDWEED, FIELD

BUCKWHEAT, WILD

THISTLE, CANADA

LETTUCE, PRICKLY

LAMBSQUARTERS

MUSTARD, WILD

MARESTAIL

TANSYMUSTARD

MUSTARD, BLUE

MORNINGGLORY

FIREWEED
25 of 34

The weed spectrums in corn and soybeans are very similar with the two crops grown primarily in 

the same areas and often rotated with each other from one year to the next. This allows corn to 

take advantage of soybean’s ability to fix nitrogen and rotating from a grass (corn) to a broadleaf 

crop (soybean) helps disrupt the lifecycle of some insects and diseases. 

CORN SOYBEANS

PIGWEED, REDROOT

LAMBSQUARTERS

WATERHEMP, COMMON

COCKLEBUR

RAGWEED, GIANT

KOCHIA

MARESTAIL

RAGWEED

MORNINGGLORY

SUNFLOWER

THISTLE, CANADA

HENBIT

SMARTWEED

WATERHEMP, TALL

HORSEWEED

REDROOT PIGWEED

COMMON WATERHEMP

VELVETLEAF

COCKLEBUR

MARESTAIL

LAMBSQUARTERS

GIANT RAGWEED

MORNINGGLORY

RAGWEED

SUNFLOWER

MUSTARD

Wild BUCKWHEAT

CANADA THISTLE

DANDELION

KOCHIA

COTTON SUGARCANE

PIGWEED, REDROOT

MORNINGGLORY

AMARANTH, PALMER'S

MARESTAIL

SICKLEPOD

COCKLEBUR

THISTLE, RUSSIAN

KOCHIA

HENBIT

PIGWEED, TUMBLE

NUTSEDGE

EVENINGPRIMROSE

CHICKWEED

MUSTARD, WILD

LAMBSQUARTERS

ALLIGATORWEED

MORNINGGLORY

AMARANTH, SPINY

GROUNDCHERRY

NIGHTSHADE, BLACK

CLOVER

PIGWEED, REDROOT

LAMBSQUARTERS

BEGGARTICKS

SICKLEPOD

DOCK, CURLY
26 of 34

Regional Data

Below are the state groupings in table and map formats that comprise the regions used to 

evaluate weed problems and to look at the top active ingredients used to control weeds in the 

selected crops.

Regions State Regions State

Northern Crescent CONNECTICUT Heartland Illinois

Northern Crescent MAINE Heartland Indiana

Northern Crescent MASSACHUSETTS Heartland Iowa

Northern Crescent NEW HAMPSHIRE Heartland Kentucky

Northern Crescent NEW JERSEY Heartland Missouri

Northern Crescent NEW YORK Heartland Minnesota

Northern Crescent RHODE ISLAND Heartland Ohio

Northern Crescent VERMONT Northern Great Plains Montana

Northern Crescent Pennsylvania Northern Great Plains Nebraska

Northern Crescent New Jersey Northern Great Plains North Dakota

Northern Crescent Michigan Northern Great Plains South Dakota

Northern Crescent Wisconsin Basin and Range Wyoming

SouthEast Delaware Basin and Range Utah

SouthEast Maryland Basin and Range Nevada

SouthEast Virginia Prairie Gateway Texas

SouthEast North Carolina Prairie Gateway Colorado

SouthEast South Carolina Prairie Gateway New Mexico

SouthEast Georgia Prairie Gateway Oklahoma

SouthEast Alabama Prairie Gateway Kansas 

SouthEast Arkansas West & FL (fruit and veg) Arizona

SouthEast Louisiana West & FL (fruit and veg) California

SouthEast Mississippi West & FL (fruit and veg) Florida

SouthEast WEST VIRGINIA West & FL (fruit and veg) Idaho

SouthEast Tennessee West & FL (fruit and veg) Oregon

West & FL (fruit and veg) Washington
27 of 34
28 of 34

The tables below show the top broadleaf weeds that growers indicated they treated for in a 2011

third party proprietary survey. Regional information is shown where there was sufficient sample 

to be reliable. Due to the smaller area grown and the concentrated growing area of some of the 

crops only a few regions may have large enough data set and in some cases only one region

contains all significant acres. An example would be Nut crops (almonds and walnuts) and citrus 

in the “West & Florida” region.

US Corn Heartland Northern Crescent Northern Great Plains Prairie Gateway

VELVETLEAF VELVETLEAF LAMBSQUARTERS VELVETLEAF PIGWEED, REDROOT

PIGWEED, REDROOT WATERHEMP, COMMON PIGWEED, REDROOT PIGWEED, REDROOT KOCHIA

LAMBSQUARTERS LAMBSQUARTERS VELVETLEAF WATERHEMP, COMMON THISTLE

WATERHEMP, COMMON RAGWEED, GIANT RAGWEED SUNFLOWER VELVETLEAF

COCKLEBUR COCKLEBUR RAGWEED, GIANT COCKLEBUR MORNINGGLORY

RAGWEED, GIANT PIGWEED, REDROOT DANDELION KOCHIA THISTLE, RUSSIAN

KOCHIA RAGWEED THISTLE, CANADA LAMBSQUARTERS BINDWEED, FIELD

MARESTAIL MARESTAIL MORNINGGLORY MARESTAIL COCKLEBUR

RAGWEED MORNINGGLORY COCKLEBUR THISTLE, CANADA THISTLE, MUSK

MORNINGGLORY HORSEWEED THISTLE SUNFLOWER SUNFLOWER

US Soybeans Heartland Northern Crescent Northern Great Plains Prairie Gateway SouthEast

 REDROOT PIGWEED WATERHEMP, COMMON LAMBSQUARTERS VELVETLEAF PIGWEED, REDROOT PIGWEED, REDROOT

COMMON WATERHEMP VELVETLEAF VELVETLEAF WATERHEMP, COMMON COCKLEBUR MORNINGGLORY

VELVETLEAF RAGWEED, GIANT PIGWEED, REDROOT COCKLEBUR MORNINGGLORY MARESTAIL

COCKLEBUR LAMBSQUARTERS RAGWEED MARESTAIL VELVETLEAF COCKLEBUR

MARESTAIL COCKLEBUR RAGWEED, GIANT PIGWEED, REDROOT SMARTWEED AMARANTH, PALMER'S

LAMBSQUARTERS PIGWEED, REDROOT DANDELION MUSTARD, WILD SUNFLOWER SICKLEPOD

 GIANT RAGWEED MARESTAIL NIGHTSHADE, BLACK BUCKWHEAT, WILD MARESTAIL SIDA, PRICKLY

MORNINGGLORY RAGWEED CHICKWEED, MOUSEEAR LAMBSQUARTERS SESBANIA, HEMP LAMBSQUARTERS

RAGWEED MORNINGGLORY MORNINGGLORY SUNFLOWER WATERHEMP, COMMSESBANIA, HEMP

SUNFLOWER WATERHEMP, TALL WATERHEMP, COMMON KOCHIA RAGWEED HENBIT

US Spring Cereals Heartland Northern Great Plains SouthEast

KOCHIA LAMBSQUARTERS KOCHIA PIGWEED, REDROOT

THISTLE, CANADA PIGWEED, REDROOT THISTLE, CANADA THISTLE, RUSSIAN

PIGWEED, REDROOT MUSTARD, WILD BUCKWHEAT, WILD LAMBSQUARTERS

MUSTARD, WILD THISTLE, CANADA MUSTARD, WILD MUSTARD, TUMBLE

BUCKWHEAT, WILD BUCKWHEAT, WILD PIGWEED, REDROOT LETTUCE, PRICKLY

LAMBSQUARTERS RAGWEED THISTLE, RUSSIAN THISTLE, CANADA

THISTLE, RUSSIAN KOCHIA LAMBSQUARTERS DOGFENNEL

LETTUCE, PRICKLY COCKLEBUR THISTLE KOCHIA

THISTLE SMARTWEED BINDWEED, FIELD MUSTARD, WILD

RAGWEED THISTLE TANSYMUSTARD MUSTARD, YELLOW
29 of 34

US Winter Wheat Heartland Northern Crescent Northern Great Plains Prairie Gateway SouthEast

KOCHIA GARLIC, WILD LAMBSQUARTERS KOCHIA KOCHIA CHICKWEED

PIGWEED, REDROOT ONION, WILD RAGWEED BUCKWHEAT, WILD BINDWEED, FIELD ONION, WILD

THISTLE, RUSSIAN HENBIT PIGWEED, REDROOT PIGWEED, REDROOT PIGWEED, REDROOT GARLIC, WILD

MUSTARD, WILD CHICKWEED VELVETLEAF THISTLE, CANADA THISTLE, RUSSIAN PIGWEED, REDROOT

BINDWEED, FIELD RAGWEED, GIANT THISTLE, CANADA THISTLE, RUSSIAN MUSTARD, WILD LAMBSQUARTERS

BUCKWHEAT, WILD RAGWEED MARESTAIL MUSTARD, WILD SUNFLOWER HENBIT

HENBIT PIGWEED, REDROOT THISTLE LAMBSQUARTERS PIGWEED, TUMBLE RAGWEED

LAMBSQUARTERS LAMBSQUARTERS DANDELION TANSYMUSTARD HENBIT MORNINGGLORY

SUNFLOWER VELVETLEAF SHEPHERD'S-PURSE SUNFLOWER MUSTARD, YELLOW MUSTARD, WILD

MUSTARD, YELLOW DEADNETTLE, PURPLE MUSTARD, WILD LETTUCE, TALL DEVIL'S-CLAW HENBANE, BLACK

PIGWEED, TUMBLE MARESTAIL RAGWEED, GIANT THISTLE LAMBSQUARTERS DOCK, CURLY

US Sorghum Prairie Gateway Northern Great Plains SouthEast

PIGWEED, REDROOT PIGWEED, REDROOT PIGWEED, REDROOT MORNINGGLORY

KOCHIA KOCHIA KOCHIA PIGWEED, REDROOT

BINDWEED, FIELD BINDWEED, FIELD THISTLE, RUSSIAN SIDA, PRICKLY

THISTLE, RUSSIAN SUNFLOWER VELVETLEAF HENBIT

PUNCTUREVINE SUNFLOWER, VOLUNTEER COCKLEBUR SICKLEPOD

DEVIL'S-CLAW THISTLE, RUSSIAN WATERHEMP, COMMON MARESTAIL

AMARANTH, PALMER'S PUNCTUREVINE LETTUCE, PRICKLY AMARANTH, PALMER'S

MARESTAIL PIGWEED, TUMBLE MARESTAIL COCKLEBUR

VELVETLEAF MORNINGGLORY THISTLE, CANADA CHICKWEED

SUNFLOWER RAGWEED SUNFLOWER SESBANIA, HEMP

US Cotton Heartland Prairie Gateway SouthEast West &FL

PIGWEED, REDROOT PIGWEED, REDROOT PIGWEED, REDROOT PIGWEED, REDROOT MORNINGGLORY

MORNINGGLORY MORNINGGLORY THISTLE, RUSSIAN AMARANTH, PALMER'S PIGWEED, REDROOT

AMARANTH, PALMER'SMARESTAIL MORNINGGLORY MORNINGGLORY NIGHTSHADE, BLACK

MARESTAIL AMARANTH, PALMER'S KOCHIA SICKLEPOD LAMBSQUARTERS

SICKLEPOD CHICKWEED PIGWEED, TUMBLE MARESTAIL SICKLEPOD

COCKLEBUR HENBIT MARESTAIL COCKLEBUR AMARANTH, PALMER'S

THISTLE, RUSSIAN BEAN, VOLUNTEER AMARANTH, PALMER'S HENBIT BINDWEED, FIELD

KOCHIA COCKLEBUR SUNFLOWER EVENINGPRIMROSE MALLOW, COMMON

HENBIT EVENINGPRIMROSE BINDWEED, FIELD CHICKWEED GROUNDSEL

PIGWEED, TUMBLE PEAVINE COCKLEBUR RADISH, WILD SOWTHISTLE
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US Fallow Land Northern Great Plains Prairie Gateway West & FL

KOCHIA KOCHIA KOCHIA LETTUCE, PRICKLY

PIGWEED, REDROOT PIGWEED, REDROOT PIGWEED, REDROOT THISTLE

THISTLE, RUSSIAN THISTLE, RUSSIAN THISTLE PIGWEED, REDROOT

THISTLE BUCKWHEAT, WILD THISTLE, RUSSIAN THISTLE, RUSSIAN

BINDWEED, FIELD THISTLE, CANADA BINDWEED, FIELD KOCHIA

BUCKWHEAT, WILD THISTLE LAMBSQUARTERS MUSTARD, WILD

THISTLE, CANADA LETTUCE, PRICKLY THISTLE, CANADA MARESTAIL

LETTUCE, PRICKLY MUSTARD, WILD MUSTARD, WILD MUSTARD, TUMBLE

LAMBSQUARTERS TANSYMUSTARD BUCKWHEAT, WILD MORNINGGLORY

MUSTARD, WILD LAMBSQUARTERS MUSTARD, BLUE BINDWEED, FIELD

US Pome Fruit West & FL Northern Cresent

LAMBSQUARTERS MALLOW, COMMON LAMBSQUARTERS

PIGWEED, REDROOT MORNINGGLORY PIGWEED, REDROOT

MALLOW, COMMON DANDELION DANDELION

MORNINGGLORY MARESTAIL THISTLE

DANDELION LAMBSQUARTERS VELVETLEAF

MARESTAIL PIGWEED, REDROOT RAGWEED

FLEABANE FLEABANE CHICKWEED

GROUNDSEL GROUNDSEL MORNINGGLORY

CHICKWEED KOCHIA PLANTAIN

THISTLE, CANADA THISTLE, CANADA BURDOCK, COMMON

US Pecans Prairie Gateway SouthEast West & FL

PIGWEED, REDROOT RAGWEED PIGWEED, REDROOT DOGFENNEL

MUSTARD, WILD ST. JOHNSWORT THISTLE, CANADA AMARANTH, SPINY

KOCHIA BROOMWEED THISTLE SICKLEPOD

PURSLANE RAGWEED, WESTERN BUTTERCUP PIGWEED, REDROOT

RAGWEED CROTON, WOOLLY DOGFENNEL THISTLE, CANADA

THISTLE, RUSSIAN IRONWEED HORSENETTLE RAGWEED

GERANIUM, DOVEFOOT PIGWEED, REDROOT RAGWEED THISTLE, BULL

MORNINGGLORY THISTLE THISTLE, BULL VIOLET, FIELD

FILAREE THISTLE, RUSSIAN COCKLEBUR NIGHTSHADE, PURPLE

NIGHTSHADE, PURPLE BULLNETTLE THISTLE, MUSK THISTLE, SCOTCH

THISTLE COCKLEBUR IRONWEED THISTLE
31 of 34

US Nut Crops US Citrus US Stone Fruit West & FL

MALLOW, COMMON SPANISHNEEDLES MALLOW, COMMON MALLOW, COMMON

FLEABANE PIGWEED, REDROOT PIGWEED, REDROOT FILAREE

FILAREE GROUNDSEL FLEABANE FLEABANE

MARESTAIL ST. JOHNSWORT FILAREE MARESTAIL

FLEABANE, HAIRY EVENINGPRIMROSE MARESTAIL CHICKWEED

CHICKWEED MARESTAIL LAMBSQUARTERS FLEABANE, HAIRY

SHEPHERD'S-PURSE FLEABANE CHICKWEED PIGWEED, REDROOT

PIGWEED, REDROOT SPURGE DANDELION CLOVER

SOWTHISTLE FLEABANE, HAIRY FLEABANE, HAIRY LAMBSQUARTERS

MORNINGGLORY RAGWEED MUSTARD, WILD BUTTERCUP

US Pasture/Rangeland Heartland Northern Great Plains Prairie Gateway Southeast

RAGWEED THISTLE, CANADA SPURGE, LEAFY RAGWEED PIGWEED, REDROOT

THISTLE, CANADA THISTLE, MUSK THISTLE, MUSK ST. JOHNSWORT THISTLE, CANADA

PIGWEED, REDROOT THISTLE THISTLE, CANADA BROOMWEED THISTLE

THISTLE THISTLE, BULL THISTLE, RUSSIAN RAGWEED, WESTERN BUTTERCUP

THISTLE, MUSK COCKLEBUR THISTLE, BULL CROTON, WOOLLY DOGFENNEL

ST. JOHNSWORT RAGWEED SUNFLOWER IRONWEED HORSENETTLE

DOGFENNEL RAGWEED, GIANT VELVETLEAF PIGWEED, REDROOT RAGWEED

IRONWEED IRONWEED KNAPWEED THISTLE THISTLE, BULL

BUTTERCUP STARTHISTLE, YELLOW KNAPWEED, SPOTTED THISTLE, RUSSIAN COCKLEBUR

HORSENETTLE KNAPWEED, SPOTTED KNAPWEED, RUSSIAN BULLNETTLE THISTLE, MUSK

US Rice West & FL Heartland SouthEast

SESBANIA, HEMP DUCKSALAD MORNINGGLORY SESBANIA, HEMP

MORNINGGLORY REDSTEM SMARTWEED MORNINGGLORY

SMARTWEED LILY SESBANIA, HEMP SMARTWEED

PIGWEED, REDROOT ARROWHEAD PIGWEED, REDROOT JOINTVETCH, NORTHERN

INDIGO ARROWHEAD, CALIFORNIA INDIGO HENBIT

JOINTVETCH, NORTHERN GALINSOGA, SMALLFLOWER ECLIPTA PIGWEED, REDROOT

HENBIT PICKERELWEED, HEARTSHAPE FALSE REDSTEM INDIGO

REDSTEM WATERHEMP, COMMON VELVETLEAF DOCK

DOCK MORNINGGLORY, BIGROOT COCKLEBUR

US Asparagus

PIGWEED, REDROOT

LAMBSQUARTERS

MARESTAIL

SMARTWEED

HENBIT

KOCHIA

NETTLE, STINGING

NIGHTSHADE, BLACK

GROUNDSEL

KNOTWEED
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Table 1. Screening Level Estimates of Agricultural Uses of 2,4-D (030001, 030004)

Sorted Alphabetically

Percent Crop Ttd.

Crop Lbs. A.I. Avg. Max.

1 Alfalfa 50,000 <1 <2.5

2 Almonds 200,000 15 20

3 Apples 80,000 20 25

4 Apricots 2,000 10 25

5 Asparagus 5,000 10 30

6 Avocados + <500 <1 <2.5

7 Barley 500,000 25 40

8 Beans, Green+ 1,000 <1 <2.5

9 Blueberries <500 <1 <2.5

10 Caneberries <500 <2.5 <2.5

11 Canola/Rapeseed + 2000 <1 <2.5

12 Cherries 30,000 15 25

13 Corn 3,200,000 5 10

14 Cotton 700,000 10 15

15 Cucumbers + <500 <1 <2.5

16 Dry Beans/Peas + 10,000 <2.5 <5

17 Fallow 2,300,000 25 30

18 Grapefruit 10,000 10 25

19 Grapes 50,000 5 15
33 of 34

20 Hazelnuts (Filberts) 20,000 25 35

21 Lemons 1,000 <2.5 <10

22 Nectarines 5,000 15 35

23 Oats 300,000 15 20

24 Onions + 3,000 5 5

25 Oranges 100,000 20 30

26 Pasture 10,600,000 10 15

27 Peaches 30,000 20 30

28 Peanuts 50,000 5 10

29 Pears 10,000 15 20

30 Peas, Green <500 <1 <2.5

31 Pecans 40,000 10 15

32 Pistachios 9,000 5 20

33 Plums 5,000 15 30

34 Potatoes 3,000 <1 <2.5

35 Prunes 20,000 15 25

36 Pumpkins <500 <1 <2.5

37 Rice 300,000 10 15

38 Sorghum 900,000 20 30

39 Soybeans 2,900,000 10 15

40 Squash 1000 <2.5 <2.5

41 Strawberries 2,000 5 5

42 Sugar Beets+ 1000 <1 <2.5

43 Sugarcane 400,000 40 65
34 of 34

44 Sunflowers + 60,000 5 10

45 Sweet Corn 7,000 5 10

46 Tangelos 1,000 30 45

47 Tangerines 2,000 10 20

48 Tobacco + 1,000 <1 <2.5

49 Tomatoes + 2,000 <1 <2.5

50 Walnuts 40,000 10 15

51 Watermelons + 1,000 <1 <2.5

52 Wheat 5,900,000 30 65

Source: EPA-HQ-OPP-2012-0330-0007 

http://www.regulations.gov/#!docketBrowser;rpp=25;po=0;dct=SR;D=EPA-HQ-OPP-2012-0330