UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C

. 20460 

### OCT 1 3 2011

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM
SUBJECT: FROM:

THRU:

TO: BEAD Chemical Profile for Registration Review: Prosulfuron (129031) Sunil Ratnayake, Biologist

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# t'\J11~ Biological Analysis Branch 

# l "ILtV, \ Sepehr Haddad, Environmental Protection Specialist 

# 1",.// J " J Science Information and Analysis Branch 

## 7

# ~ Stephen Smearman, Economist Economic Analysis Branch Biological and Economic Analysis Division (7503P) Arnet Jones, Chief 

# Ii**~ ~**  4- 11

# v....A-**~**.> Biological Analysis

# B~/' , 

# J ' > Diann Sims, Chief

## ~ Science Information and Analysis Branch Timothy Kiely, Chief ()......

# ~**,** Economic Analysis Branch

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# J \ Bio1ogical and Economic Analysis Division 3P) Andrea Mojica, Chemical Review Manager Risk Management and Implementation Branch4 Pesticide Reevaluation Division (7508P)


### Product Review Panel date: Oct. 12,2011 INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofProsulfuron, and eventually the general public. This document builds upon the data already provided in the "Usage and Label Use Data Packages" that are also provided to Registrationreview teams by BEAD. The document is based on information and data available to BEAD as ofOct. 3,2011. Prosulfuron belongs to the sulfonylurea herbicide family and it inhibits the activity of acetolactate synthase (ALS) enzyme which is important for synthesis ofbranched chain amino acids (leucine, isoleucine, and valine). Prosulfuron was registered in 1995 and it is a selective herbicide applied as a post-emergence treatment to control broadleafweeds in com, grain sorghum, winter wheat, spring wheat, barley, rye, oats, triticale, and proso millet. Prosulfuron is absorbed by leaves and roots ofsusceptible plants and provides very effective weed control at very low rates.
USE SITES Agricultural Use Sites Prosulfuron is registered for use on com, grain sorghum, winter wheat, spring wheat, barley, rye, oats, triticale, and proso millet. Non-Agricultural Use Sites Prosulfuron is not registered for non-agricultural use. COMMON FORMULATIONS AND APPLICATION METHODS Prosulfuron is formulated as water**di~persible** granules. USAGE Based onprivate market usage data from 2000-2010, usage averaged approximately 20,000 pounds active ingredient (a.i.) for 1.6 million acres treated. The average a.i. rate over this time period was 0.013 pounds a.i.!acre. Forthe 2005-2010 timeframe usage averaged approximately 15,000 pounds a.i. for one million acres treated with an average a.i. rate of0.014 pounds a.i'!acre. Figure 1presents prosulfuron usage in pounds a.i. over the 2000-2010 timeframe for wheat (spring and winter), sorghum, com and barley
.. Figure 2 presents the total area treated in acres for the same time period (proprietary Data, 2000-2010).



### 240,000**.,........-~-------------** 

# II I I 

# I • Wheat, Winter



# -.I • Wheat, Spring • Sorghum (Milo)**~** 

# •• • Corn



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# I • Barley 

### I 

# • .. ..

Years 

### Source: Proprietary Data, 2000-2010
FIGURE 2. Prosulfuron Total Area Treated in Acres (2000-2010) 3,000,000 ..,.---------------------

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### o 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Years 

### Source: Proprietary Data, 2000-2010 As shown in Figure 1 the usage ofprosulfuron was the highest in 2000-2001 gradually decreasing until 2008-2009
. There has been a slight increase inuse in 2010 from the 2008-2009 levels
. The use on com has decreased significantly during this timeframe, while the use on barley has also decreased to almost none. The use on sorghum has remained fairly steady during this time period
. 

### 3Figures 3 shows a comparison between the time periods of2000-2005, and 2005-2010, for the states with the most agricultural usage in terms ofpounds a.i. applied. Between 2000-2005 the states with the most usage were Texas (18%), Nebraska (17%), Kansas (15%), Washington (10%), and Illinois (10%). The "other" states shown in the figure for the 2000-2005 timeframe account for approximately 24 % oftota! agricultural usage and include Idaho, Kentucky, Missouri, Montana and many other states. The usage ofprosulfuron inNebraska decreased between 2005-2010. This canbe attributed to the decrease in the use ofprosulfuron on com as previously mentioned above. Relative use in Texas and Kansas increased during 2005-2010 compared to the 2000-2005 timeframe. The "other" states in Figure 3 for the 2005-2010 timeframe include Michigan, Indiana, Ohio, Louisiana, Oklahoma and many other states. FIGURE 3. Comparison ofStates with Highest Agricultural Usage ofProsulfur on between the 2000-2005 and 2005-2010 Timeframes

INDIANA

6%

10% 2000-2005

Source: Proprietary Data, 2000-2010 2005-2010



### 4BIOLOGICAL ASPECTS RELEVANT TO PROSULFURON Prosulfuron is a sulfonylurea herbicide andthe mode ofaction ofthis class ofherbicide is inhibition ofacetolactate synthase (ALS) enzyme. Presence ofmany weedspecies resistant to ALS inhibitors has been reported in the United States (Heap et al. 2011). The control ofweed species resistance to prosulfuron can be achieved by tank mixing a compatible registered herbicide with a different mode ofaction to prosulfuron. Since the introduction ofRoundup ready com in 1988, the acreage ofRoundup ready comhas increased significantly. Therefore, the observed reduction ofprosulfuron usage on com from 2000 to 2010 may be due to the increase ofglyphosate usage in Roundup ready comproduction in the United States. mSTORY OF BEAD ASSESSMENTS FOR PROSULFURON There was one document in the BEAD Official Records files that included prosulfuron as a control alternative. The 2003 document entitled "Assessment ofthe Potential Mitigation Measures for Atrazine" included prosulfuron as an alternative to control a variety ofbroad leaf weeds in sorghum. Sorghum became a registered use ofprosulfuron in 1996 and by 2003 prosulfuron was used on less than 5% ofgrain sorghum acreage. However, based on the information in Figure 1, while overall prosulfuron use has declined since 2000, the number of pounds applied to sorghum has remained steady given year to year fluctuations since 2003. This suggests that prosulfuron still has a role as a broadleafweed control. There were no Section 18 requests for the use ofprosulfuron for any site in the BEAD Section 18 Official Records. DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON PROSULFURON There are no data gaps identified by BEAD at this time.
REFERENCES Heap,"I, H. Glick, L Glasglow, and W. Vencill. 2011. Herbicide Resistant Weeds by Country and Site ofAction. 2011. http://www.weedscience.org/summary/countrysummarv.asp
. Pesticide Fact Sheet. Prosulfuron. EPA National Library Network. 2011. http://cfpub.epa.gov/ols/cataloglcatalog display.cfm?&FIELD 1 =SUBJECT&INPUTI=Prosulfur on&TYPEl=EXACT&item count=l. Product Label. EPA Registration No. 100-763. 2010. Syngenta Crop Protection Inc.Greensboro, North Carolina. http:/ /www.syngentacropprotection.com/pdf/labels/SPC763BM9H1209
. pdf
. Proprietary Data, 2000-2010.



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