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

## SEP 2·0 

## 2011

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM SUBJECT: FROM: BEAD Chemical Profile for Registration Review: Mepiquat Chloride (109101) Sunil Ratnayake, Biologist 

# /I 1_ 0 Biological Analysis Branch 

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## v'f \**~** SepebrHaddad, Environmental Protection Specialist 

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# ~ Science Information and Analysis Branch 

## If John Faulkner, Economist

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# d h Nt /I A Economic Analysis Branch

## ~ W \ Biological and Economic Ana ysis Division (7503P) 

### THRU: Arnet Jones, Chief 

# /J.. tIJ.J Biological Analysis Branch

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# i., Diann Sims, Chief Science Information and Analysis Branch
, Timothy Kiely, Chief

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### A/I ' Economic Analysis Branch
.**VV~** \ Biological and Economic Analy' ivision (750 

### TO: Carissa Cyan, Chemical Review Manager Risk Management and Implementation Branch 1 Pesticide Reevaluation Division (7508P) 

### Product Review Panel date: July 20, 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 ofmepiquat chloride (109101), and eventually the general public. This document builds upon the data already provided inthe "Usage and Label Use DataPackages" that are also provided to Registration Reviewteams by BEAD. The document is based oninformation and data available to BEAD as ofJuly 13, 2011.

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Mepiquat chloride is a systemic, foliar applied plant growth regulator extensively used in cotton production as a harvest-aid. In addition, there is also a minor usage on wine grapes. The active ingredient ofthis chemical was first registered in the United States in 1980 (EPA, 1997). Mepiquat chloride is a gibberellic acid suppressant and it is absorbed bythe green portions of plants. This plant growth regulator reduces cell elongation, and plantheight (York, 1983a& Kerby, 1985) and has been associated withenhancing earliness offruiting and fruit development (Walter, et al., 1980; York, 1983b; Kerby, 1985). USE SITES Agricultural Use Sites Mepiquat chloride is used as a plant growthregulator and registered for use on cotton and grapes. Non-Agricultural Use Sites Mepiquat chloride is not registered for non-agricultural use. COMMON FORMULATIONS AND APPLICATIONMETHODS Mepiquat chloride is formulated as pelletedltabletted, water dispersible granules, water soluble and emulsifiable concentrate. Application methods include water spray, oil spray, and aerial application. USAGE Based onprivate market usage data from 1998-2010, usage averaged approximately 400,000 pounds active ingredient (a.i.) for 14 million acres treated (Proprietary Data, 1998-2010). The average a.i. rate overthis time period has remained fairly constant at approximately 0.03 pounds a.i./acre. Figure 1presents mepiquat chloride usage over the 1998-2010 timeframe for cotton, the major use (over 99.5%). Minor mepiquat chloride usage (less than 1 %) has been reported on wine grapes, while minor usage has also beenreported ontobacco, which is not a registered site.

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FIGURE 1. 

### MepiquatChloride Usage on Cotton (1998-2010) 700,000

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Years Source: Proprietary Data, 1998-2010 Between 1998-2010, the states withthe most agricultural usage interms ofpounds a.i. applied were Texas (18%), Georgia (15%), Arkansas (13%) and Mississippi (11 %). Usage has also been reported inNorth Carolina, Tennessee, Missouri, California, Louisiana, and Alabama each with less than 10%. (Figure 2). The "other states" (7%) in Figure 2 include Arizona, South Carolina, Florida, Oklahoma, and Virginia. 

### FIGURE2. States with HighestUsage on Cotton (1998-2010)
ALABAMA
5% CALIFORNIA 5% MISSOURI 6% TENNESSEE 7%
CAROLINA 9% Source: Proprietary Data, 1998-2010 11%

As shown in Figure 1, between 1998 and 2010, the lowestuse ofme piquat chloride was reported in 1998, while use reached a peak in 2005. In 2005, the total areatreated was also the highest during the 1998-2010period. Use has been increasing steadily each year from 2008 through


### 32010. Figure 3 presents the states with the highest pounds a.i. used from 1998-2000, as compared to the states with the highest pounds a.i. usedfrom 2008-2010. As shown in Figure 3, use in Texas and Georgia has increased significantly within the last decade (total area treated has increased inthese two states by more than 50%), while use in Californiahas decreased during the same period from approximately 12% to only 3% oftotal pounds a.i. applied, and use in Tennessee has decreased by 50% during the same timeframe. FIGURE 3. Comparison ofStates with Highest Usage Between 1998-2000 and 2008-2010 Timeframes

5% TENNESSEE 5% NORTH

7% 1998-2000

11% 2008·2010

11% Source: Proprietary Data, 1998-2010



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BIOLOGICAL ASPECTS RELEVANT TO MEPIQUAT CHLORIDE The cottonplants treated with mepiquat chloride become shorter and narrowerwiththicker, smaller leaves. This will result inbetterearly boll retention and/or largerbolls. Mepiquat chloride can also reduce the boll rot and improve defoliation. Itallows the growerto manage the cottonplant for short-seasonproduction, reducing yield and quality losses due to a delayed and prolonged harvest. Mepiquat chloride is a gibberellic acid suppressant and it is absorbed bythe greenportions ofthe plant. Ithas beenreported that leaves and stems ofglyphosate resistant cotton are more resistant to glyphosate compared to the cotton fruits and treatments with mepiquat chloride has produced greater portion ofcotton bolls in lower parts ofthe plant and improved the fiber quality (Nuty et aI., 2006). HISTORY OF BEAD ASSESSMENTS FOR MEPIQUAT CHLORIDE Emergency exemptions were approved in 1998 for the use ofmepiquat chloride in New York, Ohio and Pennsylvania on grapes to enhance fruit set to overcome frost damage. These exemptions imply that mepiquat chloride had benefits on grapes that were not provided by the alternatives. No other BEAD assessments were found. DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON MEPIQUAT CHLORIDE There are no data gaps identified by BEAD atthis time. REFERENCES 1). EPA. 1997. Re-registration Eligibility Decision(RED) Mepiquat Chloride. http://www.epa.gov/oppsrrdl/REDs/2375red.pdf 2). Kerby, T.A. 1985. Cotton response to mepiquat chloride. Agron. J. 77:515-518. 3). Nuti, R. T., Viator, R. P., Casteel, S., Edmisten, K., and R. Well. 2006. Effect ofplanting date,
.mepiquat chloride, and glyphosate application to glyphosate resistant cotton in North Carolina. Agron. J. 98:1627-1633. 4), Proprietary Data, 1998-2010. 5). Walter, H., H.W. Gausman, F.R. Rittig, L.N. Namken, D.E. Escobar, and R.R. Rodriguez. 1980. Effect ofmepiquat chloride on cottonplant leafand canopy structure and dry weights ofits components. p. 32-35. 

### In J.M. Brown (ed.) Proc. Beltwide Cotton Prod. Res. Conf., St. Louis, MO. 6-10 Jan. 1980. National Cotton Council ofAmerica. Memphis, TN. 6). York, A.C. 1983a. Cotton cultivar response to mepiquat chloride. Agron. J. 75:663-667. 7). York, A.C. 1983b. Response ofcottonto mepiquat chloride withvarying N rates and plant populations. Agron. J.75:667-672.

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