1 of 3 4 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 SUPPLEMENTA RY 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.com2 of 34 DISTRIBUTION PAGE

DED Code: D1C / B1C

bcc: Laura Tagliani, 308/2E Greg Orr, 308/2E Heidi Reistad, 308/2E Federal Action Files, 308/2E unstapled3 of 34 

## 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 .......................................................................................................1 1
Soybean..................................................................................................1 3

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

Fallow and Burndown Uses...........................................................................1 5
Sorghum.................................................................................................16

Pasture...................................................................................................1 8
Asparagus................................................................................................ 20

Corn......................................................................................................2 1

References...............................................................................................2 2

Question 4.
Appendix 1

... ... ........................................................................ ................ .2 34 of 34 

## DOW AGROSCIENCES RES PONSE 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 manageme nt 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 cro pping system (e.g. no

till, 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, an d 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, weed

free 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 erosi on. 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 percent age 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. A vailable information on key broadleaf weeds in these crops is provided in Appendix 1

. Examples of w eed control programs, herbicide information, and costs are provided
, but more detailed information can be found in various state crop production and weed ma nagement guides referenced at the end of each section.5 of 34 

### Small Grains (Wheat, Barley, Oats, Rye)

Weed Management Programs and Options : E ffective 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 i nto 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 her bicide 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 compet itive, 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
trea ted 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 use d 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. T he 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 s hould become more prevalent, viable alternative s 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 sec tion
, lists a number of alternative herbicide s and estimated costs. M etsulfuron, 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,6 of 34 

### 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. Weed s 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 harro wing 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 b roadleaf herbicides currently available for use in sm all grains.

Herbicide (common name) MOA 1 Crops 2 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 o nly in premix w/ bromoxynil Florasulam 2 WW, SW, B, O .004 7.20 Available o nly 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=rye7 of 34 

### 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. Th is vegetative cover
, either via resident vegetation or planted cover
crops, provide s 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, p roperly 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 duri ng 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 co mmon. 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).8 of 34 

### 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 dichlobe nil, 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 alte rnative herbicid es and estimated costs.

Table 2

. Postemergence b roadleaf herbicides currently available for use in tree crops

Herbicide (common name) MOA 1 Crops 2 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://pnwha ndbooks.org/weed/sites/default/files/chapters/pdf/l

orchardsandvineyards.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/l

orchardsandvineyards.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.html10 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 va rieties, 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 wee ds requiring early control to avoid potential yield loss due to competition. Typically planted in August or September, s ugarcane is most susceptible to weed competition during the first eight to ten weeks after cane emergence. A split application of herbi cide 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 an d 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 (S ept

. - 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, metri buzin, 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, di u ron, metribuzin, pendimethalin, sulfentrazone, trifluralin, flumioxazin or hexazinone+diruron. Morningglory can cause a significant problems at sugarcane harvest t hus a late application prior to harvest of 2,4

- D,11 of 34 

### 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 c arfentrazone, flumioxazin, sulfentrazone, halosulfuron and atrazine
, provide control of key broadle af 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 A 1 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 seaso n vigor and competitiveness. A soybean

- soybean

- rice rotation is recommended over a12 of 34 

### 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 r ice 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 estab lishment 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 fo r 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 timi ng 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 h erbicide 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),
tr iclopyr (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 n ot 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 broad leaf 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 herbicide s 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 b roadleaf herbicides currently available for use in rice

.

Herbicide (common name) MO A 1 Rate (lb ae or ai /A ) Cost/Acre Comments

2,4

- D 4 1 .25

- 1 .5 5.75

- 7

. 0 0 Aciflurofen 14 .125 Bensulfuron 2 .0375

- .0625 Bentazon 0.75

- 1.0 18.00

- 25.00 Bispyribac 2 .32

- .63 Carfentrazone 14 .0 25

- .0 5 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+Cont rol+Guide.htm14 of 34 

### Soybean
Herbicides and Management Options: Soybean is an annual crop th at 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 U nited S tates are glyphosate

- tolerant and glyphosate is the primary herbicide used. Approximately 40

- 50% of soybean acres receive a preplant or
preemergence , soil

- residual h erbicide followed by 1

- 2 postemergence applicatio ns 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 chlori muron. 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 sm all 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 ot her 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.

So urces:
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 r ows (3 8

- 40 inches apart). Use of no

- till crop culture is common in cotton and herbicides

are a n important means of weed control. Currently, most cotton varieties in the U nited S tates 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 of15 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 , th is 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 poste mergence 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 d epending 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 c rop 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 so il 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

- spectr um, non

- selective herbicides such as glufosinate or paraquat. Herbicides with utility16 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 ca n 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 measu res. 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 b urndown herbicides currently available for use in corn, soybeans, cotton and small grains

.

Herbicide (common name) MOA 1 Crops 2 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 .0 5

- .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.cfm17 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. Establish ing 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 t his 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 chemi cal 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 t ank 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 incre ased 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 of ten used for the control of summer annual, broadleaf weed species including common lambsquarters, ragweed, and pigweed. S everal possible alternative herbicid es and estimated costs are shown below in T able 6 . Atrazine, for example, provides control equiva lent 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

ear ly 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) MOA 1 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 nutrie nts 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 cult ural, 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 over

grazed 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 graz ing 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 g ood translocation to roots and other19 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 inh ibitors (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. T able 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) MOA 1 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 estimates20 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 (WS SA Group 4), ALS inhibitors (WSSA Group 2) and Photosynthesis inhibitors (WSSA Group 7). Auxin resistant weeds are not know n 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 shou ld 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) MOA 1 Rate (lb ae or ai/A) Cost/Acre

2,4

- D 4 1 .5

- 2 .0 7

. 5 0

- 10.00 Clopyralid 4 .1 9

- . 2 5 1 4

. 00

- 18

. 0 0 Dicamba 4

. 2 5

- .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 category21 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 otherwis e 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 succes sful 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 a reas. 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.cfm22 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 E xcel file s; ‘ 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 U nited S tates under different management practices and have different weed issues. Regional information is shown where sample size was de emed 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, PRICKLY24 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 FIREWEED25 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 d isrupt 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, CURLY26 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) Washington27 of 3428 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 w h ere 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 ex ample 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, COMM SESBANIA, 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, YELLOW29 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'S MARESTAIL 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 SOWTHISTLE30 of 34 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 THISTLE31 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 KNOTWEED32 of 34 

### 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 2 00,000 15 20

3 Apples 8 0,000 20 2 5

4 Apricots 2,000 1 0 25

5 Asparagus 5,000 10 30

6 Avocados + <500 <1 <2.5

7 Barley 5 00,000 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 , 2 00,000 5 10

14 Cotton 7 00,000 10 15

15 Cucumbers + <500 <1 <2.5

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

17 Fallow 2, 3 00,000 2 5 30

1 8 Grapefruit 1 0,000 1 0 25

19 Grapes 5 0,000 5 1533 of 34 2 0 Hazelnuts (Filberts ) 2 0,000 25 3 5

2 1 Lemons 1,000 <2.5 < 10

2 2 Nectarines 5 ,000 15 35

2 3 Oats 300,000 15 20

2 4 Onions + 3,000 5 5

2 5 Oranges 1 0 0,000 20 30

2 6 Pasture 10 , 6 00,000 10 15

27 Peaches 30,000 20 30

28 Peanuts 5 0,000 5 10

29 Pears 10,000 15 20

3 0 Peas, Green <5 00 <1 <2.5

3 1 Pecans 4 0,000 10 1 5

3 2 Pistachios 9 ,000 5 2 0

3 3 Plums 5,000 15 30

3 4 Potatoes 3,000 <1 <2.5

3 5 Prunes 2 0,000 15 25

3 6 Pumpkins <500 <1 <2.5

37 Rice 300,000 10 15

38 Sorghum 900,000 20 30

39 Soybeans 2, 9 00,000 10 1 5

4 0 Squash 1000 <2.5 <2.5

4 1 Strawberries 2,000 5 5

4 2 Sugar Beets + 10 00 <1 <2.5

4 3 Sugarcane 400,000 40 6534 of 34 4 4 Sunflowers + 60,000 5 10

4 5 Sweet Corn 7 ,000 5 10

4 6 Tangelos 1,000 30 45

47 Tangerines 2 ,000 10 2 0

48 Tobacco + 1,000 <1 <2.5

49 Tomatoes + 2 ,000 < 1 <2.5

5 0 Walnuts 40,000 10 15

5 1 Watermelons + 1,000 <1 <2.5

5 2 Wheat 5, 9 00,000 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