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 ~ L 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 

Science 

Sims, 

Information 

Chief 

and 

~ 

Analysis Branch 

Timothy Kiely, Chief ()...... ~ , Economic Analysis Branch <.....J J \ 

Bio1ogical and Economic Analysis Division 3P) 

Andrea Mojica, Chemical Review Manager 

Risk Management and Implementation Branch 4 

Pesticide Reevaluation Division (7508P) 

Product Review Panel date: Oct. 12,2011 

INTRODUCTION 

The purpose of this document is to convey usage information and a broad overview of the pest 

management roles of pesticides that are beginning to undergo registration review. The 

anticipated audience consists of the team of EPA staff currently evaluating the registration status 

of Pro sulfur on, 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 Registration 
review teams by BEAD. The document is based on information and data available to BEAD as 

of Oct. 3,2011. 

Prosulfuron belongs to the sulfonylurea herbicide family and it inhibits the activity of 

acetolactate synthase (ALS) enzyme which is important for synthesis of branched 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 of susceptible 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 on private 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. For the 2005-2010 timeframe usage averaged approximately 

15,000 pounds a.i. for one million acres treated with an average a.i. rate of 0.014 pounds 

a.i'!acre. Figure 1 presents 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). 

2 
40,000 .,........-~-------------

II 

I I I • Wheat, Winter 

-. I 

• Wheat, Spring 

• Sorghum (Milo) 

~ • • • Corn 

o I • Barley 

I • .. .. 

Years 

Source: Proprietary Data, 2000-2010 

FIGURE 2. Prosulfuron Total Area Treated in Acres (2000-2010) 

3,000,000 ..,.---------------------

II> 

GI 

.. 

u 

c( 

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 of prosulfuron was the highest in 2000-2001 gradually 

decreasing until 2008-2009. There has been a slight increase in use 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. 

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Figures 3 shows a comparison between the time periods of 2000-2005, and 2005-2010, for the 

states with the most agricultural usage in terms of pounds 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 of pro sulfur on in Nebraska decreased between 2005-2010. This can be attributed to 

the decrease in the use of prosulfuron 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 of States with Highest Agricultural Usage of Pro sulfur on between 

the 2000-2005 and 2005-2010 Timeframes 

INDIANA 

6% 

10% 

2000-2005 

Source: Proprietary Data, 2000-2010 

2005-2010 

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BIOLOGICAL ASPECTS RELEVANT TO PROSULFURON 

Prosulfuron is a sulfonylurea herbicide and the mode of action of this class of herbicide is 

inhibition of acetolactate synthase (ALS) enzyme. Presence of many weed species resistant to 

ALS inhibitors has been reported in the United States (Heap et al. 2011). The control of weed 

species resistance to prosulfuron can be achieved by tank mixing a compatible registered 

herbicide with a different mode of action to prosulfuron. Since the introduction of Roundup 

ready com in 1988, the acreage of Roundup ready com has increased significantly. Therefore, 

the observed reduction of pro sulfur on usage on com from 2000 to 2010 may be due to the 

increase of glyphosate usage in Roundup ready com production 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 of the Potential Mitigation 

Measures for Atrazine" included prosulfuron as an alternative to control a variety of broad leaf 

weeds in sorghum. Sorghum became a registered use of prosulfuron in 1996 and by 2003 

prosulfuron was used on less than 5% of grain 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 of prosulfuron 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 of Action. 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/SPC763BM9H 1209 . pdf. 

Proprietary Data, 2000-2010. 

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