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: ~:!!"=~S~~~~h /

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kh; \ ~ 

THRU: 

TO: 

Sepehr Haddad, Environmental protecti~n Specialist 1/1 fA,. I 

Science Information and Analysis Branch / ~ ~ r~ 

Andrew Lee, Economist af c ~ Economic 

Biological 

Analysis 

and Economic 

Branch 

Analysis Division (7503P) 

., ~ 

Arnet Jones, Chief 

Biological Analysis Branch 

Diann Sims, Chiefj{)~ Science Information and Ang' ranch ~ 

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 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 ametryn, 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 March 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 of action of this class of herbicides is inhibition of 

photosynthesis. Ametryn is currently used for selective control of broadleaf and grassy weeds in 

com, pineapple, and sugarcane. Ametryn can be 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 on non-agricultural sites. 

USAGE 

Agricultural Usage 

.Based on private market usage data from 2000-2010, usage averaged approximately 200,000 

pounds active ingredient (a.i.) for 350,000 acres treated. Figure 1 presents usage of ametryn 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 period was 

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 of pounds a.i. applied were field com 

(65%) and sugarcane (35%). Between the 2006-2010 timeframe the same two crops (field com 

grown in North Carolina, and sugarcane grown in Florida) accounted for the major use (field 

com 51 %, and sugarcane 49%), even though total 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 our proprietary data source does not survey 

crops grown in Hawaii, no use was reported for sugarcane grown in Hawaii or on pineapples, 

even though ametryn is used for weed control on pineapples in Hawaii (Zinn and Smearman, 

2005). 

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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 t$- s:>'b s:>OJ ~t;::, ",(3 ",(3 ",(3 ",(3 ",(3 ~ ",(3 ",(3 ~ ~ ~ 

Years 

Source: Proprietary Data, 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 most pounds 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. 

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FIGURE 3. Comparison of States with Highest Use of Ametryn- Percent of Total 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 of usage is the use intensity. In this analysis, the use intensity is 

expressed as the pounds a.i. applied per acre of land in farms. This differs from the 

application rate, which is expressed as the pounds a.i. applied per treated 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 in Mississippi between 2006-2010. 

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

Average Pounds per 

1,000 Acres of Fannland 

_ <9 

D 9-20 

21 - 41 

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

USDA, 2007. Census of Agriculture. . 

This is a map of agricultural pesticide usage at the Crop Reporting District (CRD) level. CRDs 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 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 of pesticide 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 of the survey. 

CRDs showing no usage of pesticides may be due to either the lack of pesticide use in the 

region or non-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. 

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BIOLOGICAL ASPECTS RELEVANT TO AMETRYN 

Ametryn is a member of the herbicide class oftriazines. The benefits of triazine herbicides are 

low cost, flexibility of herbicide applications, highly effective weed control, crop selectivity, 

residual activity, and usage in reduced tillage practices (LeBaron et al., 2008). Triazines also 

increase the value of crop rotations by reducing weed populations and weed seed 

banks in crops commonly rotated with triazine-treated crops. The mode of action of triazine 

herbicides is inhibition of photosynthesis. This mode of action is extremely important for 

managing development of herbicide resistance in weeds against glyphosate and ALS inhibiting 

herbicides. Due to the extensive usage of triazine herbicides, about 24 weed species have 

developed resistance to the mode of action of triazines in the United States (Heap et al., 2011). 

Triazines are mostly applied as tank mixed products to obtain a broad spectrum of weed control 

and to manage the development of herbicide resistance. Among the triazines, ametryn is the 

most powerful 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 of ametryn on these crops is significantly low. This implies that there are niche uses for 

ametryn on these crops. For example, use of ametryn on field com as lay by treatments to 

control troublesome weeds such as broadleaf signalgrass (Brachiaria platyphylla), Texas 

panicum (Panicum texanum), and nutsedges (Cyperus spp.), was reported in North Carolina 

(York et al .. 2000). The observed decrease of total areage treated with ametryn from 2004 

onwards may be due to the rising popularity of glyphosate tolerant com in the United States. 

mSTORY OF BEAD ASSESSMENTS FOR AMETRYN 

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 on pineapples in Hawaii. Ame'tfYn: is widely used on pineapple acreage in Hawaii 

despite higher costs compared to some of the 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 in pineapple production. 

INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON 

AMETRYN 

Obtaining additional information on the following items would improve future BEAD 

assessments of the importance of Ametryn and may be required as part of the registration review 

of this pesticide. 

Usage information on pineapples and sugarcane in Hawaii, specifically pounds a.i. used, and 

application rates. Also, since the chemical is registered for use on popcorn, 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 of Action. 2011. http://www.weedscience.org/summary/countrysummary.asp . 

LeBaron, H. M., J. E., McFarland, and O. C. Burnside. 2008. The Triazine Herbicides: A 

Milestone in the Development of Herbicide Technology. Pages 1-12. In LeBaron, H. M., J. E., 

McFarland, and o. C. Burnside eds. The Triazine Herbicides 50 years of Revolutionizing 

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Agriculture. 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 of Agriculture. 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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