UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D .C. 20460


### MAY 23 2011

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM
SUBJECT: BEAD Chemical Profile for Registration Review: Orthosulfamuron (108209)
FROM: Sunil Ratnayake, Botanist Biological Analysis Branch

Stephen Smearman, Economist Economic Analysis Branch Biological and Economic Analysis Division (7503P) THRU:

TO: Arnet Jones , Chief Biological Analysis Branch Diann Sims, Chief

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# J;rMScience Information and

## Analysis~ranch Timothy Kiely, Chief Economic Analysis Branch · 

## J Biological and Economic Analys Division (7 ) James Parker, Chemical Review Manager Risk Management and Implementation, Branch 1 Pesticide Reevaluation Division (7508P) 

### Product Review Panel date: May 18,2010 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 ofOrthosulfamuron, 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
1Registration Review teams by BEAD. The document is based on information and data available to BEAD as ofMay 5, 2011. Briefdescription ofthe pesticide, including chemical class, mode ofaction, and main target pests. Orthosulfamuron, a member ofthe sulfonylurea family, is a systemic herbicide that can be used for the control ofannual and perennial broadleafweeds and sedges in rice production fields. Orthosulfamuron inhibits the activity ofaceolacte synthase enzyme (ALS) which is important for the synthesis ofbranched chain amino acids {leucine, isoleucine, and valine) in susceptible weeds. Orthosulfamuron is applied as an early post-emergence treatment and has a broad spectrum of selectivity at a very low rate. It is rapidly absorbed through leaves and roots and translocated in to the other plant tissues. Selectivity mechanism involves the differential rates ofmetabolism in different weed species (Isagro, 2011). Orthosulfamuron is suitable for weed control in both water seeded and dry seeded rice production (orthosulfamuron Technical Bulletin, 2010). USE SITES Agricultural Use Sites This herbicide is recommended for the control ofannual and perennial grasses, sedges, and broadleafweeds found in rice fields. COMMON FORMULATIONS AND APPLICATION METHODS Orthosulfamuron is formulated as water dispersible granules and emulsifiable concentrate. This herbicide can be applied using ground (tractor mounted sprayers and spreaders) and aerial equipment. USAGE Agricultural Usage Orthosulfamuron was registered for use on rice in 2007. Approximately 3 million acres ofrice is grown in the United States. Based on private market usage data from 2007-2010, usage averaged approximately 3,000 pounds active ingredient (a.i.) for 45,000 acres treated on rice, the only registered use site, as shown in Figure 1. Since 2007 the use oforthosulfamuron on rice has steadily increased through 2010. Orthosulfamuron is typically applied one time per year at a rate of0.06Ibs. a.i. per acre (Proprietary Data, 2007-2010). The states with the most agricultural usage for the years 2007- 2010 in terms ofpounds a.i. applied were Arkansas (69%) and Missouri (30%) as shown in Figure 2. Minor use was also reported in California (1 %) (proprietary Data, 2007-2010).

2FIGURE 1. Orthosulfamuron Usa e 6,000 ...-----------------------



### o 2007 2008 2009 2010 Years 2007 -2010, Proprietary Data



### FIGURE 2.

2007-2010, Proprietary Data



### 3Non-Agricultural Usage BEAD reviewed available data sources, but there was no information on orthosulfamuron nonagricultural use. BIOLOGICAL ASPECTS RELEVANT TO ORTHOSULFAMURON Description ofother unique issues including resistance, plant health claims, and public health issues. Presence of43 weed species resistant to ALS inhibitors has been reported in the United States (Heap et al. 2011). However, no reports could be found on the herbicide resistant weeds, specifically, to orthosulfamuron in rice production fields in the U.S. Halosulfuron, penxosulam, bensulfuron, bispyribac sodium, and propanil are the most competitive registered post-emergence herbicides to orthosulfarnuron. Except propanil, mode ofaction ofthese herbicides is similar to orthosulfamuron. Compared to orthosulfamuron, and halosulfuron, penoxsulam has a greater efficacy on water hyssop 

### (Bacopa spp). However, it is less effective on controlling alligator weed 

### (Alternanthera philoxeroides)
. Compared to orthosulfamuron, bispyribac sodium, and propanil have a greater activity on watergrass species and they are less effective on weed species such as ducksalad 

### (Heteranthera spp.) and yellow nutsedge 

### (Cyperus esculentus). Also, bensulfuron provides a poor control of watergrass species 

### (Echinochloa spp.) (Texas Rice Production Guidelines, 2010). mSTORY OF BEAD ASSESSMENTS FOR ORTHOSULFAMURON EAB searched the BEAD data base for previous assessments for orthosulfamuron. The search results found only one document in the BEAD Official Records which was a Public Interest Finding in which BEAD determined that the availability oforthosulfamuron would be in the public interest (Ratnayake, 2006). Orthosulfamuron was considered as an alternative to control watergrass weeds resistant to propanil, cyhalofop and fenoxoprop in rice fields in California (Ratnayake, 2006). There were no other documents found in BEAD's Section 18, QUA or Use and Usage Request data bases. INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON ORTHOSULFAMURON BEAD specific Registration Review issues, as relevant, including BEAD data gaps needed for future assessments and BEAD work plan. There are no data gaps identified by BEAD at this time.

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### REFERENCES 2007-2010, Proprietary Data. 2010. Texas Rice Production Guidelines. http://beaumont.tamu .edu/eLibrary/Bulletins/20 10 Rice Production Guidelines.pdf Orthosulfamuron Technical Bulletin. ISAGRO. http://www.isagro.com/images/stories/file/PDF /Orthosulfamuron%2OTechnical%20Bulle tin%20may2010 .pdf . Accessed on May 5, 2011. Heap, I, H. Glick, L Glasglow, and W. Vencill. 2011. Herbicide Resistant Weeds by Country and Site ofAction. http://www.weedscience .org/summary/countrysummary.asp Ratnayake, S. 2006. Review ofPublic Interest Documentation for the Registration of Orthosulfamuron Herbicide for Control ofSedges, Broadleaf, and Aquatic Weeds in Rice Production. DP 

### # 327089. A Publication ofEnvironmental Protection Agency.

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