UNITED STATES ENVIRONMENTAL PROTECTION A G ENC Y WASHINGTON , D
. C

. 20460 

### MAY 0 7 2014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM
S U BJECT: 

### FROM:

THRU :

TO: B EAD Chemical Profile (BCP) for Registration Review: Cyhalofop-butyl (082583) 

### Bill Phillips, Agronomist / Biological**Anal~ B~~ch**  ·

# ~£:~~~ental Protection Specialist Science Information and Analysis Branch Derek Berwald, Economist 

## f-rK 

# R( --, 

# .J- vv.._

# ~ Economic Analysis Branch 

# V/j Biological and Economic Analysis Division (7503P) Arnet Jones, Chief 

# a ...**~~** Biological Analy s is Branch**~r. ~**  

# U
Diann Sims, Chief

# ~~ Sc ience Information and Analysis Branch Timothy Kiely, Chief 

# fr**I~~.~~~** Economic Analysis Branch 

## vvv Biological and Economic Analy Division (75 Jolene Truj illo, Chemical Review Manager Risk Management and Implementation Branch 5 Pesticide Re-eval u ation Divi sion (7508P)


### Peer Review Panel date : 2 Ap r il2014

1SUMMARY Cyhalofop-butyl is an herbicide that is labeled for grass weed control in rice only. Grass weed control is difficult to achieve in a grass crop such as rice. However, cyhalofop-butyl is a selective herbicide that makes controlling difficult to manage weeds possible without damaging rice crops in which it is applied. Most ofthe use of cyhalofop-butyl is in Arkansas and California, the two large st rice producing states. While these state s account for the majority of the herbicide use, nationally, between 2008 and 2012 15% ofthe total rice crop was treated with this herbicide. BEAD concludes that there are important uses for this herbicide. In rice production there are a few key weeds that pose sig n ificant problems for growers. Cyhalofopbutyl is used in combination with other herbicides to control some of these key weed species, including herbicide resistant biotypes.
INTRODUCTION The Biological and Economic Analys is Division (BEAD) Chemical Profile (BCP) provides an overview of the pest management roles and quantitative usage information for cyhalofop-butyl. The BCP includes summaries of previous BEAD products and available public and/or private use and usage data for cyhalofop-butyl to describe the role of this chemical in pest management. Addi tional information on use is available in the cyhalofop-butyl Label Data Report and Screening Level Usage Analysis (SLUA). Information provided in this BEAD Chemical Profile (BCP) may be used by stakeho lders (e.g., users and registrants), OPP risk and benefit assessors, and OPP risk managers, and the general public during the Registration Review process ofthis pesticide. USE SITES Cyhalofop -buty l is re gistered for use on rice only. There are no other use s (agricultural or nonagricultural) for this chemical. FORMULATIONS AND APPLICATION METHODS Cyhalofop-butyl is formulated as an emulsifiable concentrate, soluble concentrate, granular, and ready-to-use solution. This chemical can be broadcast aerially or by foliar application with ground equipment. This herbicide is applied postemergence in both flooded and dryland rice crops to contro l annual grass. HISTORY OF CYHALOFOP-BUTYL AND BEAD PRODUCTS The only BEAD work on cyhalofop-butyl was for two Section 18 emergency exemption requests from th e early part of this century. The use was requested to control weed s in rice for Louisiana (EPA 2002) and California (EPA 2001). In both cases the use was requested for control of emerging weed problems for which the states did not have efficacious alternatives. BEAD agreed with this assessment. Later cyhalofop-butyl was registered for these uses.

2U SAGE Usage Trends For years 2003-2012, cyhalofop-butyl annual usage averaged 103,000 pounds of active ingredient 

### (A.I.) treating an annual average of 406,000 thousand acres, for an overall average application rate of 0.25 pounds A
. 

### I. per acre. As shown in Figures 1 and 2, use , both in terms of pounds 

### AI. and total area treate d peaked in 2005, and has decreased overa ll until the most recent years for which data is available ( Proprietary Data, 2003

- 20 1 2). Some ofthis decline can be attributed to the dec li ne in rice acreage, but acreage treated with cyhalofop

-butyl has decreased more than acreage has. App li cation Rates From 2008

- 2012, an average o f 81,000 pounds of cyhalofop-butyl was used on rice. The average total acres treated 1 for the same period was 311,000 for an average app lica tion rate of 0.26 pounds 

### A.l. per acre (Proprietary data, 2008

- 2012)
. 

### Figure 1. 

### Avera e Pounds ofC 2003-2012 200,000 .,...---------- -------------



## < "' "0 c:**~** 0 Q.

0**+--~-- r--** **~-~r- -.--** **-. --** **.- --** **-. --** **-.** 2003 2004 2oos 2006

### 2oo1ea~oos 2009 2010 2011 2012 Source: Proprietary Data, 2003-2012

1 *Total Acres Treated sums all acres treated for a crop, including those acres that receive multiple treatments.

3

### Figure 2. Total Area Treated 800,000 .------ -------- ----------

0**+--~ --r-** **-~-~~ -~-~--~** **-~-~**

2003 2004 2005 2006

### 200te**~008** 2009 2010 2011 2012

As shown in Table 1, use is only seen in the rice growing states, and most of the use is concentrated in Arkansas and California, the two largest production states. These two states account for about 

### 70% of the total use of cyhalofop-butyl in the nation, both in the ea rly period and from 

### 2008

- 2012. While these states account for the majority of the herbicide use, nationally, between 

### 2004 and 

### 20 1 2 15% ofthe national rice crop was treated with this herbicide (SLUA). California's share of national use is somewhat higher than the share of national rice production, indicating that cyhalofop-butyl is more important there than in other states. This can also be seen in Tab le 2, which shows the percent of the rice crop treated with cyhalofop-butyl by state. In both time periods, the states with the highest percentage ofthe crop treated are Californi a and Mississippi. Note, however, th at the percent treated is much higher in the earlier period than from 

### 2008

- 2012. This matches the general use pattern shown in Figures 1 and 

### 2, which show the cyhalofop-butyl has declined over time. 

### Table 1. Compar i son of States with Highest Use of Cyhalofop -b utyl Percent of Total Lbs. Applied Between the 2003-2007 and 2008-20 1 2 Timeframes 2003

- 20 07 2008

- 2012 % ofTotal % ofTotal State P ounds Applied State Pounds Applied Nationallv Nationally Arkansas 41 Arkansas 41 California 29 California 29 Louisiana 14 Mississippi 12 Mississippi 10 Louisiana 10

Missouri 4 Texas 5

Texas 2 Missouri 3 Source: Proprietary Data , 2003-2012

4

### Table 2
. Percent of Crop Treated by State, 2003

-2007 and 2008

- 2012 2003-2007 2008-2012 Average Average Average Average Percent Total Percent T otal State of Crop Area Total State of Crop Area Total Pounds Pounds Treated Treated AI Treated T reated AI (Acres) (Acres) Arkansas 13 203,000 50,000 Arkansas 5 127 ,000 33,000 California 27 146,000 35,000 California 10 92,000 24,000 Louisiana 12 69,000 18,000 Louisiana 5 30,000 8,000 Mississippi 22 53,000 13,000 M ississippi 11 37,000 10,000

Missouri 9 19,000 5,000 Missouri 2 9,000 2,000

T exas 7 12,000 3,000 Texas 6 16,000 4,000 Source: Proprietary Data, 2003-2012 Geographi c Distribut ion of Cyha lofop

-butyl Use Another measure of usage is the agricultural use intensity. In this analysis, the use intensity is expressed as the average annual amount (in pounds) ofthe active ingre dient applied per 

### 1 ,000 acres of crop acres grown. This differs from the app lication rate , which is expressed as the pounds a.i. applied per treated area. Figure 3 spatially represents cyhalofop-butyl's use intensity in the U.S. from 

### 2008

- 2012. Because cyhalofop

-butyl is only used on rice, the map is showing the major rice producing states, wi th relatively high intensity in the two states with the highest production Arkansas and Ca li fornia. Although Mississippi has a relatively high percentage ofthe crop tr eated with cyha lofop-butyl , use intensity i s lower than, for examp le, Arkansas, because there is relatively little rice acreage there. For more information about this map, see Appendix A.

5Figure 3 . Cyhalofop- b utyl U sage by Crop Reporting District (2003-2012)

Pounds Active Ingredient per 1,000 Crop Acres Grown 

## D o .o 0 <0
.2

- 0.2-1
. 5

. 1
. 6

- 1
.7

- >1
. 8
CYHALOFOP-B U T YL AND USE CHARACTERISTICS Cyhalofop-butyl is an aryloxphenoxy propionate herbicide in the Weed Science Society of America herbicide mechanism o f action group one, with the mechanism of action of inhibiting the enzyme acetyl CoA carboxylase (ACCase). This herbicide is applied postemergence in both flooded and dryland r ice crops to control annual grass weeds along with seedling perennial grass weeds. ROLE OF CYHALOFOP-BUT YL IN PEST MANAGEMENT Grass weed control is difficult to achieve in a grass crop such as rice. Herbicides that control grass weeds usually control or damage grass crops such as rice. However, cyhalofop-butyl is a selective herbicide that makes controlling difficult to manage weeds possib le without damaging rice crops in which it is applied. Cyhalofop-butyl controls grasse s that can result in yield losses in rice crops. Weeds controlled by this herbicide include such di fficult to control grass weeds as barnyardgrass (Echinochloa crus-galli) and sprangletop (Leptochloa dubia) (Fischer 2010). In California barnyardgrass has been found to have biotypes that are reported to be resistant to this herbicide. However, the predominant weed in t his state in rice production is sprangletop, which cyh alofop-butyl is often

6used 

### in tank mixes to control (Fischer 201 0). In Arkansas this herbicide is important in the control ofbarnyardgrass. This species has biotypes that are resistant to three of the most commonly used herbicides in rice production for the contro l of barnyardgrass; clomazone, propanil and quinclorac (Wilson et al. 201 0). Overall, because of its ability to control the herbicide resistant weed barnyardgrass in Arkansas and sprangletop in California, cyhalofopbutyl can be an important part of an integrated weed management program. DATA NEEDS The Agency currently does not h ave important information on cyhalofop-butyl. Obtaining the following information may improve future assessments conducted by the Agency related to the use and importance of cyhalofop

- butyl. Agricultural Use • Information on any additional niche weeds that this herbicide is used specifically to control.

REFERENCES BEAD, 2014. Cyha lofop -but y l Screening Level Usage Analysis. Biological and Economic Analysis Division , Office of P esticide Programs, US Environmental Protection Agency. February, 2014 EPA, 2001. Dietrich , Virginia and Frank Hernandez, Review of Request for Emergency Exe mption for Use of Cyhalofop-butyl (ClincherTM) on Rice to Control Bearded Sprangletop in California (01-CA-15) [DP Barcodes 02733377, and 0273379] , April 5, 2001 EPA , 2002. Werling, Virgini a and Frank Hernandez, Review of Request for Emergency Exemption for Use of Cyhal of op - buty l (ClincherTM) to Control Perennial Grasses Including K.notgrass in Rice in Louisiana (02-LA-03) [OP Barcode 0281087], March 27 , 2002. Fischer, A., et al. Ca lifornia weed control strategies. 2010. Available at: http: //www .ricefarming.com/home/issues / 20 11-03 /2 0 11
_ MarStrategies.html Nickerson , C
. , R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses of Land in the United States, 2007. USDA/ ERS. Economic Information Bulletin Number 89. Proprietary Data. 2003-2012. (pesticide usage data) US Census. 2012. Statistica l Abstract of the United States 2012. Table 358



### 7USDA, 2006-20 10. NASS Crop Reporting Districts (shape file ofCRDs). Available at: http: //www .ers.usda.gov/br}efing/arms/resourceregions/resourceregions
.htm#nass
. U SDA, 2006

- 2010. NASS Crop Reporting Districts. Available at: http: //www.nass.usda.gov/D ata and Statistics/County Data Files/Frequently Asked Questi ens/county list.txt USDA, 2007. Census of Agriculture. Available at: http: //www . agcensus.usda
. gov/Publications/ 2007 /index.asp
. USDA, 2007. Census of Agriculture. (for Land in Farms data). Available at: http: //www.agcensus .usda.gov/Publications /2007 /index.asp
. Wilson, M., J. Norsworthy, D. Johnson, R. Scott, and C. Starkey. 2010. Herbicide programs for managing herbicide -resistant barnyardgrass in Arkansas rice. Avai l able at : http: / / arkansasagnews. uark.edu/591-26.pdf

8APPENDIX A The map included herein is primarily for the use of the risk assessors in the Environmenta l Fate and Effects Division
. The map provides a very broad geographical view ofthe amount (in pounds) ofthe active ingredient a pplied per 1 , 000 acres of"land in farms "
. These data are included in the maps because ris k assessors are interested in the amount of a pesticide used across farmland. Because of the definition of Land in Farms, as discussed below, the calculated values presented in the map are not equivalent to an app licat ion rate (lbs a i /A). The data used to make these maps have many limitations. Any interpretation ofthe maps should consider the underlying data and the associated limitations carefully. The smallest areas shown on t4e maps within each state are Crop Reporting Districts (CRD). CRDs are defined by USDA and each consists of multip le counties that have similar soils, growing conditions , and farming practices
. The CRDs w ithin many states have roughly the same area. Because it is not feasible to conduct an agricultural survey that samples every county in the United Sta tes , the use of CRDs al low for a sample to be collected that represent a much larger area with relative ly homogeneo us agricultural characteristic s. The numerator (annual average pounds applied) is based on private market surveys ofpesticide use in agriculture averaged over the last five years (Proprietary Data, 2007

- 2011). These surveys cover about 60 crops and are targeted in states that produce the majority of the crop. Although the surveys capture mos t of the u se of a particular active ingredient in agriculture, there are several limitations to these surv eys.
• States with minor production of a surveyed crop are not sampled • Not all types ofpesticide s are surveyed in every crop in every year • Many specialty crops \Yith very small acreages are not included in the survey The result of these limitations is that CRDs that show no usage may actually have a small amount of the active ingredient being used. The denominator (1,000 Acres ofland in farms) was selected from the Ce n su s of Agricu l ture (USDA, 2007) to represent agricultural acreage tha t is actively managed and include s most of the



### 9areas treated with pesticides. The category "Land in Farms" is defined by the Census of Agriculture as being made up offour components: • Total cropland • Permanent pasture • Total woodland • Land in farmsteads, buildings, livestock facilities, ponds, roads , wasteland, etc. This category includes land in the various USDA conservation programs. It s hould be noted that the Census of Agriculture does not include grazing land rented (on a p er-animal basis) from the Bureau of Land Management or Forest Service, thus it is an underestimate ofthe land being managed for agricultural purposes. The reader should pay particular attention to the figure legends and realize that a map prepared for a particular chemical is not directly comparable to a map prepared for a di fferent chemical. Scale and units of measurement do matter and may be different between maps.

10