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

### APR 05 

## 2012

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM SUBJECT: FROM:

THRU:

TO: BEAD Chemical Profile for Registration Review: Rimsulfuron (129009) Sunil Ratnayake, Biologist Biological Analysis Branch

# (kJ-\~ Cynthia Doucoure, Environmental Protection Specialist

### ~ Science Information and Analysis Branch Stephen Smearman, Economist

# ~~ Economic Analysis Branch Biological and Economic Analysis Division (7503P) Arnet Jones, Chief Biological Analysis Branch Diann Sims, Chief

# /1t~ Science Information and Analysis Branch Timothy Kiely, Chief 

# 91 \1\1\

# ~ Economic Analysis Branch V\I \ Biological and Economic Analysis ivision (7 Jose Gayoso, Chemical Review Manager Risk Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P)


### Product Review Panel date: March 7, 2012 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 ofrimsulfuron, and eventually the general public
. This document builds uponthe data already provided inthe "Usage and Label Use DataPackages" that are also provided to Registration Review teams by BEAD. The document is based on information and data available to BEAD as ofMarch 5, 2012.BACKGROUND Rimsulfuron was ftrst registere, d as an herbicide inthe U.S. in 1994. This herbicidebelongs to the sulfonylureaherbicide family and mode ofaction ofthis herbicide is inhibition ofthe activity ofacetolactate synthase (ALS) enzyme which is important for synthesis ofbranched chain amino acids (leucine, isoleucine, and valine). Rimsulfuron is a selectiveherbicide applied as fallow, pre-plant, pre-emergence, and post-emergence treatments to control broadleafand grassy weeds on crops described below. Rimsulfuron is absorbed by leaves and roots ofsusceptible weeds and provides effective weed control at very low application rates compared to manyotherherbicides.


### USE SITES Agricultural Use Sites , Rimsulfuron is labeled for use on grapes, vineyards, citrus fruits, nut crops, pome fruits, stone fruits, tropical and sub-tropical fruits, fruiting vegetables, root crop vegetables, seed and pod vegetables, com, cotton, orchards, fruit trees, soybeans, chicory, chinquapin, and farmyards (including fuel storage areas, uncultivated areas, fallow land and barrier strips). Non-Agricultural Use Sites Rimsulfuron is also labeled for non-residential use onrangeland, ornamental lawns and turf, ornamental trees, drainage systems, and uncultivated non-agricultural areas (airports, rights-ofway, roadsides, utility substations, pipelinepumping stations, sewage disposal areas, industrial sites, lumber yard,tank farms, and fencerows).
COMMON FORMULATIONS AND APPLICATION METHODS Rimsulfuron is formulated as water dispersible granules (dry flowable), emulsifiable concentrates, and soluble concentrates/solids
. This herbicide canbe applied using the following application methods: ground and aerial applications, broadcast applications (followed in some instances by soil incorporation), band applications, and chemigation.
USAGE Agricultural UseTrends. 1998-2010 Rimsulfuron use interms ofaverage pounds a.i. applied inthe U.S., as reported in private market research surveys, fluctuated between 1998 and 2010, with a steep decline inusage after 2004, followed by a slightupward trend inrecent years (Figure 1). Similarresults were found in terms oftotal acres treated. The top agricultural crops treated with rimsulfuron (pounds applied) during this period were com (84%), potatoes (6%), tomatoes (5%), and almonds (2%). Figure 2 shows the use pattern ofrimsulfuron use on the major crops. During this period, on average, 92,000 pounds ofrimsulfuron were applied to 7,404,000 acres per year at an overall average application rate of0.OI2Ibs/acre.

2Figure 1. RimsulfuronUse Trend: Pounds A.I. Applied, 1998-2010 120,000

...:

- RIMSULFURON 0 i ---r co (i'I 0 ..-t N 

## fB g II)**~** l' co C'l 0 C'l (i'I 0 0 0 0 0 0 0 ..... O"l CTI 0 0 0 0 0 0 0 0 0 0 0 .-I ..... N N N N N N N N N N N Years
Source: Proprietary Data, 1998-2010

Figure 2. Rimsulfuron Use Trend: To Markets for Pounds A, I. A lied,1998-201O

120,000

# I

I "2"**~ ~** **~** <II 

## =a Do IV 

# .- ra :9 

# --_ ........ 

# _-

o -Corn (left axis) T 24,000

- - Potato ----Tomato ••••••• Almond

- Other

:

### ........ .;. 

## : '-... 

# .... ::-...._-_.. I

• T 

# j 0 

# i Q, 

## ...

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 Year Source: Proprietary Data, 1998-2010 "Other" crops include almonds, apples, apricots, cantaloupes, celery, cherries, cotton, dry beans/peas, grapes (raisin, table, and wine), lemons, oranges, peaches, pears, pistachios, plums/prunes, soybeans, sunflowers, sweet com, and walnuts.



### 3Agricultural Use, 2006-2010 Based on private market pesticide usage data from 2006-2010, agricultural usage ofrimsulfuron averaged approximately 79,000 pounds annually and was applied on average to approximately 5,355,000 acres at an overall average application rate of0.015 lbs per acre, a 25% increase over the 1998-2010 average application rate. Decreased use ofrimsulfuron, particularly oncom, continued at the beginning ofthis period followed by a slight increase in usage in**rece~t** years due in part to the increased use ofrimsulfuron on potatoes, tomatoes, almonds and othercrops. The top agriCUltural crops in terms ofpounds ofrimsulfuron during this period were com (72%), potatoes (8%), tomatoes (7%), and almonds (4%) as shown inFigure 3
. Similarresults were found in terms oftotal acres treated.**F~e** 3. Rimsulfuron: Top Crops for Pounds A.1. Applied, 2006-2010 Almonds

Source: Proprietary Data, 2006-2010 The states with the most agricultural usage ofrimsulfuron in terms ofpounds a.i. applied were California (20%), Iowa (15%), Missouri (8%) and lllinois (7%). However, interms oftotal acres treated, the top states are Iowa (19%), Missouri (10%), lllinois (9%), California (7%), Nebraska (7%), and Minnesota (6%) as shown in Figure4. Rimsulfuron is also used on a variety ofother crops in over 30 additional states and accounts for 50% ofpounds a.i. applied and 55% oftotal acres treated during this period.



### 4Figure 4. Rimsulfuron: Top States, 2006-2010

Other, 50% 

### Ib applied

8% Source: Proprietary Data, 2006-2010 Other 55% 

### acres treated

"Other" states include AL, AR, CO, DE, FL, GA, ID, KS, KY, LA, ME, MD, MI, MN, MT, NJ,**n~~~~~~~~~m~~~m~~** Agricultural Usage by Crop Reporting District a 7%

Iowa 19%

Another measure ofusage is the ilse intensity. Inthis analysis, the use intensity is expressed as the pounds a.i. applied per acre ofland in farms. This differs from the application rate, which is expressed as the pounds a.i. applied per treated acres. Figure 6 spatially represents rimsulfuron's use intensity in the U.S., which is relatively greater in California, Iowa, Minnesota, Missouri, Michigan, and Maryland.



### 5Figure 6. Rimsulfuron Usage by Crop Reporting District (2006 - 2010)

Average Pounds Per 1,000 Acres of Farmland
• <O.OB 0
.OB

- 0.17 0 0
.1B-O
.31

. 0
. 32-0.8

. 0
. 61-1.25

Source: Proprietary Data (2006-2010)
This is a map of agricultural pesticide usage at the Crop Reporting District (CRO) level. CROs are boundaries created by USDA NASS which are aggregates of counties (USDA, 2010). Pesticide usage is displayed as average pounds (for the years 2006-2010) per 1,000 acres of farmland in a CRO to normalize for the variation in farmland between CROs. Farmland acreage was obtained from USDA (2007). Usage is based on private market surveys ofpesticide use in agriculture (Proprietary Data, 2006- 2010). The survey data are limited to the states that represent the top 80-90% of acreage for the individual crops, therefore, use may be occurring in regions outside the scope ofthe survey. CROs showing no usage ofpesticides may be due to either the lack ofpesticide use in the region or nonparticipation in the agricultural surveys. In addition, across the years, there may be variations in the specific crops included in the CRD survey. This may result in a lower annual average for the CRO.



### 6Non-Agricultural Use No available national-level usage data were found for use ofrimsulfuron onnon-agricultural use sites. 

### BIOLOGICAL ASPECTS RELEVANT TO RIMSULFURON Rimsulfuronbelongs to the family of sulfonylureaherbicides and the mode ofaction ofthis class ofherbicides is inhibition ofacetolactate synthase (ALS) enzyme. Thepresence of44 weed species resistant to ALS inhibitors has beenreported in the United States (Heap et al. 2011). However, according to this database, no reports were found on development ofresistance specifically for rimsulfuron. The control ofweed species resistance to ALS inhibitors can.be achieved bytank mixing compatible registered herbicides with a different mode ofaction to rimsulfuron. The investigations onpostemergence applications ofrimsulfuron plus thifensulfuron-methyl with various acetolactate synthase (ALS)- and non-ALS-inhibitor herbicides for weed control in comhas reported a greater control (95%) ofgiant foxtail (Setaria faberi) and commonlambsquarters (Chenopodium album) by

### tank mixing rimsulfuron with thifensulfuron-methyl (Isaacs et al., 2002). 

### IDSTORY OF BEAD ASSESS:MENTS FOR RIMSULFURON InMarch 2011 there were two Section 18 requests for the use ofrimsulfuron mixed with thifensulfuron to control broadleafweeds in chicory production in the BEAD Official Records database. The BEAD reviews ofthe Section 18 Emergency Exemption Requests from Nebraska (11 NE-03, 11-NE-04) (DP# 386264, DP# 386265) and Wyoming (11 -WY-02,11- WY-03) (DP# 386266, DP# 386267) determined thatthe requests did not qualify as urgent and non-routine situations underFIFRA Section 18 guidelines because there were sufficient alternatives already registered and available. There were no other assessments or Section 18 requests in the BEAD Official Records database for rimsulfuron. 

### CONCLUSION The rimsulfuron usage trend is mixed. The major use market for rimsulfuron, com, decreased based onproprietary data. It appears thatrimsulfuron is not as beneficial as it once was for com growers as glyphosate has absorbed market share · once held byrimsulfuron. Even though there is increasing resistance to glyphosate, it is notcertain that the rimsulfuron market will return for com. Thenumber ofrimsulfuron pounds ofactive ingredient used on com dropped nearly 50% inthe period from 2004 to 2010 while thetotal number ofpounds ai ofglyphosate applied to com annuallyhas increased in the same timeperiod. However, rimsulfuron is seeing an increase inuse on other crops as more sites are approved for registration. For almond growers and other nut and fruit treeproducers, increase inusage suggests that rimsulfuron has become a very beneficial tool. Its use in terms ofpounds a.i. applied on almonds has increased by over 350% in the period between 2008 and 2010. For field crops such as potatoes and tomatoes, rimsulfuron's use has remained constant during the time period from 1998-2010 so growers still have a need for rimsulfuron onthese two and similar crops.

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### INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON RIMSULFURON Obtaining additional usage information onnon-agricultural uses ofrimsulfuron would assist BEAD with improving future assessments regarding the importance ofrimsulfuron. Usage information may also berequired as part ofthe registration review ofthis pesticide. 

### REFERENCES Heap, I, H. Glick, L Glasglow, and W. Vencill. 2011. Herbicide Resistant Weeds by Country and SiteofAction. 2011. http://www.weedscience.orglsummary/countrysummary.asp
. Isaacs, M. A., H. P. Wilson, and J. E. Toler. 2002. Rimsulfuron Plus Thifensulfuron-Methyl Combinations with Selected PostEmergence BroadleafHerbicides in Corn (Zea mays). WeedTehnology 16:3, pp. 664-668. Proprietary Data, 1998-2010. Ratnayake, S., and J. Faulkner. 2011. Review ofSection 18 Emergency ExemptionRequests from Nebraska (11 NE-03, I I-NE-04) (01 '# 386: 164,01' # 386265) and Wyoming (11

-WY-02, ll-WY-03) (01'# 386266,01'#386267) for Use ofBasis· (Thifensulfuron and Rimsulfuron) to Control BroadleafWeeds in Chicory Production. USDA, 2006-2010. NASS Crop Repprting Districts. Online: http://www.ers.usda.govlbriefing/arms/resourceregions/resourceregions.htm#nass
. USDA, 2007. Census ofAgriculture. Online: http://www.agcensus.usda.gov /Publications/2007/index.asp
.

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