UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C

. 20460 

### MAR 30 201Z

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM SUBJECT: BEAD Chemical Profile for Registration Review: Ametryn (080801)


### FROM:

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TO: Sepehr Haddad, Environmental

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# 1 fA,. I Science Information and Analysis Branch /

# ~**~ r~**  Andrew Lee, Economist 

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

# Chiefj{)~ Science Information and

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### ~ Timothy Kiely, Chief

### ~ Economic Analysis Branch Biological and Economic AnalYSIS Division (7503P) Molly Clayton, Chemical Review Manager Risk Management and Implementation Branch 3 Pesticide Re-evaluation Division (7508P)

Product Review Panel date: March 21, 2012 INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest managementroles ofpesticides that are beginning to undergo registrationreview. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofametryn, 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 ofMarch 14,2012.Ametryn was first registered as a pesticide in the U.S. in 1964 (USEPA, 2005). Ametryn belongs to the herbicide class oftriazines and the mode ofaction ofthis class ofherbicides is inhibition of photosynthesis. Ametryn is currently used for selective control ofbroadleafand grassy weeds in com, pineapple, and sugarcane. Ametryn canbe applied as pre-emergence and as a post- ' emergence directed spray. COMMON FORMULATIONS AND APPLICATION METHODS Ametryn is formulated as water dispersible granules and can be applied by conventional ground sprayers. Aerial application is allowed in Florida for sugarcane only. USE SITES Agricultural Use Sites Ametryn is labeled for use on com (field and pop), pineapple, and sugarcane. Non-Agricultural Use Sites Ametryn is not registered for use onnon-agricultural sites. USAGE Agricultural Usage .Based onprivate market usage data from 2000-2010, usage averaged approximately 200,000 pounds active ingredient (a.i.) for 350,000 acres treated. Figure 1presents usage ofametryn over this time period for field com and sugarcane, the crops for which usage data was reported. Figure 2 presents total area treated in acres which has fluctuated between 2000 and 2004, and has been decreasing from 2004 onwards. The average a.i. rate during the 2000-2010 time periodwas approximately 0.31 pounds per acre for sugarcane and approximately 1.1 pounds per acre for field com. Between 2000-2005, the crops with the major use in terms ofpounds a.i. applied were field com (65%) and sugarcane (35%). Between the 2006-2010 timeframe the same two crops (field com grown inNorth Carolina, and sugarcane grown in Florida) accounted for the major use (field com 51%, and sugarcane 49%), even thoughtotal pounds a.i. applied decreased from the 2000- 2005 timeframe. (Proprietary Data, 2000-2010). Figure 1 shows that use on sugarcane is dropping consistently over the 2006-2010 time period, while use on field com is highly variable. Since ourproprietary data source does not survey crops grown in Hawaii, no use was reported for sugarcane grown in Hawaii or onpineapples, eventhough ametryn is used for weed control on pineapples in Hawaii (Zinn and Smearman, 2005).

2

### FIGURE 1. Ametryn Usage on Field Corn and Sugarcane in Pounds A.I. Applied (2000- 2010)250,000 ...,----------------

-+-Corn**Sugarcane ~t;::,**  s:>'" S:>'" s:>",**~ ~<,** **~<o** 

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### Source: ProprietaryData, 2000-2010 FIGURE 2. Amet n Total Area Treated in 

### Acres (2000-2010) 500,000 -.----------------------

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

### Source: Proprietary Data, 2000-2010 Figure 3 compares the states with the most agricultural usage between the 2000-2005 and the 2006-2010 timeframes. The states with the mostpounds a.i. applied in both timeframes were Florida and North Carolina, even though the pounds applied decreased between 2006 and 2010 in both states. The "other" states in the 2000-2005 timeframe include Texas, Illinois, and Louisiana. 

### 3FIGURE 3. Comparison ofStates with Highest Use ofAmetryn- Percent ofTotal Lbs. Applied Between the 

### 2000-2005 and the 

### 2006-2010 Timeframes 

### 2000-2005 2006-2010

GEORGIA 5% Avera e = 225,000 lbsl ear

Source: Proprietary Data, 

### 2000-2010 Avera e=150,000 lbsl ear

Another measure ofusage is the use 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 pertreated acre. Figure 4 spatially represents ametryn use intensity in the US, with the most intense use in North Carolina followed by Florida. There was also a very small amount used on less than 500 acres treated inMississippi between 2006-2010.



### 4FIGURE 4. Ametryn Usage by Crop Reporting District (2006-2010)

Average Pounds per 1,000 Acres of Fannland



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Source: USDA, 2006-2010. NASS Crop Reporting Districts

. USDA, 2007

. Census ofAgriculture.

. This is a map ofagricultural pesticide usage at the Crop Reporting District (CRD) level. CRDs are boundaries created by USDA NASS which are aggregates ofcounties (USDA, 2010). Pesticide usage is displayed as average pounds (forthe years 2006-2010) per 1,000 acres offarmland in a CRD to normalize for the variation in farmland between CRDs

. 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 thatrepresent the top 80

-90% ofacreage for the individual crops, therefore, use may be occurring in regions outside the scope ofthe survey. CRDs showing no usage ofpesticides may be due to either the lack ofpesticide use in the region ornon-participation 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 CRD.



### 5BIOLOGICAL ASPECTS RELEVANT TO AMETRYN Ametryn is a member ofthe herbicide class oftriazines. The benefits oftriazine herbicides are low cost, flexibility ofherbicide applications, highly effective weed control, crop selectivity, residual activity, and usage in reduced tillage practices (LeBaron et al., 2008). Triazines also increase the value ofcrop rotations byreducing weed populations and weed seed banks in crops commonly rotated withtriazine-treated crops. The mode ofaction oftriazine herbicides is inhibition ofphotosynthesis. This mode ofaction is extremely important for managing development ofherbicide resistance in weeds against glyphosate and ALS inhibiting herbicides. Due to the extensive usage oftriazine herbicides, about 24 weed species have developed resistance to the mode ofaction oftriazines inthe United States (Heap et al., 2011). Triazines are mostly applied as tank mixed products to obtain a broad spectrum ofweed control and to manage the development ofherbicide resistance. Among the triazines, ametryn is the mostpowerful triazine herbicide as far as the weed control spectrum is concerned (LeBaron et al., 2008). However, compared to other herbicides used on field com and sugarcane, the total usage ofametryn onthese crops is significantly low. This implies that there are niche uses for ametryn onthese crops. For example, use ofametryn on field com as lay by treatments to control troublesome weeds such as broadleafsignalgrass (Brachiariaplatyphylla), Texas panicum (Panicum texanum), and nutsedges (Cyperus spp.), was reported inNorth Carolina (York et al

.. 2000). The observed decrease oftotal areage treated with ametryn from 2004 onwards may be due to the rising popularity ofglyphosate tolerant com inthe United States. mSTORY OF BEAD ASSESSMENTS FORAMETRYN BEAD conducted an alternatives analysis for ametryn on sugarcane, pineapple, and com (field, pop, and sweet corns) (Zinn and Smearman, 2005). This assessment provided information on ametryn use onpineapples in Hawaii. Ame'tfYn: is widely used onpineapple acreage in Hawaii despite higher costs compared to some ofthe other registered herbicides. Given that few alternatives are available and that ametryn is widely used despite higher costs, BEAD infers that ametryn may be an important herbicide inpineapple production. INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK ON AMETRYN Obtaining additional information onthe following items would improve future BEAD assessments ofthe importance ofAmetryn and may be required as part ofthe registration review ofthis pesticide. Usage information onpineapples and sugarcane in Hawaii, specifically pounds a.i. used, and applicationrates. Also, since the chemical is registered for use onpopcorn, any usage information relating to this use would be useful.
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/countrysummary.asp

. LeBaron, H. M., 

### J. E., McFarland, and O. C. Burnside. 2008. The Triazine Herbicides: A Milestone inthe Development ofHerbicide Technology. Pages 1-12. In LeBaron, H. M., J. E., McFarland, and 

### o. C. Burnside eds. The Triazine Herbicides 50years of Revolutionizing 6Agriculture. Elsevier. 525 B Street, Suite 1900, San Diego, CA 92101-4495, USA. http://www.lybrary.comlthe-triazine-herbicides-50-years-revolutionizing-agriculture-p94646.html

. Proprietary Data, 2000-2010. USDA, 2006-2010. NASS Crop Reporting 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

. USEPA, 2005, Zinn, N. and S. Smearman. Alternatives Analysis for Ametryn on Sugarcane, Pineapple, Field Com, and Popcorn, DP 307118. York, A. C., and A.S. Culpepper. 2000. Weed Management. 

### In North Carolina Com Production Guide. North Carolina Cooperative Extension Service, North Carolina State University. http://www.ces.ncsu.edulplymouth/cropsci/cornguide/

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