UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON , D

.C

. 20460 

### SEP 26 2011

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM SUBJECT: FROM:

THRU:

TO: BEAD Chemical Profile for Registration Review: Tralkoxydim (121000) Sunil Ratnayake, Biologist

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. 0 Biological Analysis Branch 

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## ~ Jihad Alsadek, Economist

## ,z::2:s~ Science Information and Analysis Branch**~** Andrew Lee, Economist

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# Ct\- \Iv\... Economic Analysis Branch 

### \j

# J Biological and Economic Analysis Division (7503P) Arnet Jones, Chief

# ~**1** Biological Analysis Branch

### ~' "I Diann Sims, Chief 

# $0'**LA.>'Scf~Yt** Science Information and Analysis Branch Timothy Kiely, Chief 

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# ~ Economic Analysis

### Branch**~)** Biological and Economic Analysis Division 503P) Katherine St. Clair, Chemical Review Manager Risk Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P)


### Peer Review Panel date: Sep. 7, 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 ofTralkoxydim (121000), 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 of09-06-2011.

1Tralkoxydim is a member ofthe cyclohexanedione group ofherbicides. The mode ofaction of this herbicide is inhibition ofacetyl-coA carboxylase. Tralkoxydim is recommended for the control ofannual grass weeds in wheat, barley, and triticale. It is a systemic, foliar applied postemergence herbicide recommended for selective control ofmajor grassy weeds such as wild oat 

### (Avenafatura L.), green foxtail 

### (Setaria viridis), yellow foxtail 

### (Setaria lutescens), Italian ryegrass 

### (Lolium multiflorum), and Persian darnel 

### (Loliumpersicum). To increase the weed control spectrum, tralkoxydim can be tank mixed with compatible broadleafherbicides. USE SITES Agricultural Use Sites Wheat, barley, and triticale Non-Agricultural Use Sites There are no non-agricultural uses. COMMON FORMULATIONS AND APPLICATION METHODS Tralkoxydim is formulated as water dispersible granules and soluble concentrate only. It is applied by ground and aerial methods. USAGE Figure 1 provides usage trends, in terms ofpounds applied, for the largest agricultural markets for tralkoxydim. The use oftralkoxydim on spring wheat, barley and other crops fluctuated during the period 1998-2010. There was a significant increase in use on spring wheat in 2000. There was also a sharp increase in use oftralkoxydim on barley in 2002 -2003 and a sharp decrease in 2005 on this crop. From 2006-2010, the most recent available usage data, annual total agricultural usage averaged approximately 34,000 pounds active ingredient for 190,000 treated acres for an average application rate of0.2 lbs. a.i. per acre. During this period, the crops with the most use in terms oftotal pounds ofactive ingredient applied are spring wheat (58%) and barley (30%). On average, the states with the most agricultural usage in terms ofpounds a.i. applied are Montana (57%), Idaho (19%), and North Dakota (14%). (Proprietary Data, 2006-2010). USE TRENDS As shown in Figure 2, 

### Tralkoxydim Agricultural Usage Data, from 2006 -2008, use on barley declined by 64%, while the use oftralkoxydim on spring wheat and other crops fluctuated with no clear trend. Use on spring wheat increased dramatically in 2010.

2Figure 1. 

### Tralkoxydim Agricultural Usage Data (1998-2010)

Pounds A.I. 180,000 ...----------------------



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"Other crops" includes winter wheat (12% oftotal usage). Source: Proprietary Data, 1998-2010
Figure 2. 

### Tralkoxydim Agricultural Usage Data (2006-2010) 50,000 

### '1------------------- • Wheat, Spring
• Barley • Other

PoundsA.I. . Wheat, Spring • Barley 

### o • Other 2006 2007 2008 2009 2010 Years "Other crops" include winter wheat (12%).

Source: Proprietary Data, 2006-2010
BIOLOGICAL ASPECTS RELEVANT TO TRALKOXYDIM The mode ofaction oftralkoxydim herbicide is inhibition ofacetyl-coA carboxylase enzyme (ACCase) which is involved in the synthesis oflong chain fatty acids. Tralkoxydim is a member ofthe cyclohexanedione group ofherbicides and belongs to the Group A herbicides according to the classification ofthe Herbicide Resistance Action Committee (HRAC). Weeds such as wild

3oat (A vena fatua), downy brome (Bromus tectorum), smooth crabgrass (Digitaria ischaemum), large crabgrass (Digitaria ischaemum), barnyard grass (Echinochloa crus-galli), late watergrass (EchinochloaphyUopogon), Amazon sprangletop (Leptochloapanicoides),Italian ryegrass (Lolium multiflorum),Persian darnel (Loliumpersicum), little seed canary grass (Phalaris minor)Itchgrass (Rottboellia exalta), giant foxtail (Setariafaberi), Johnsongrass (Sorghum hale pense) are some ofthe weeds which have developed resistance to Group A herbicides in the United States (Heap, 1997). The development ofresistance in many weed species may have contributed to some extent to the reduction in tralkoxydim usage. HISTORY OF BEAD ASSESSMENTS FOR TRALKOXYDIM There have been no BEAD assessments since 2000. DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON TRALKOXYDIM There are no known data gaps at this time. REFERENCES Acetyl coenzyme A carboxylase. (2011). In Encyclopa!dia Britannica. Retrieved from http://www.britannica.comlEBcheckeditopic/3307/acetyl-coenzyme-A-carboxylase
. Heap, 

### 1. M. 1999. Occurrence ofHerbicide Resistant Weeds, Worldwide. http://www.weedscience.com/paper/resist97.htm Proprietary Data, 1998-2010.

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