UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C

. 20460 

## MAY 28 2013

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM SUBJECT:
FROM:

THRU:

TO: BEAD Chemical Profile (BCP) for Registration Review: Fluthiacet-methyl (108803) Sunil Ratnayake, Biologist 

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### ~-**~~(\~~** SepehrHaddad, EnvironmentalProtection Specia!LJ

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## ~\f-./ ' \1/ \ Biological and Economic Analysis Division (7503P) Arnet Jones, Chief /.)
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# .A..l Biological Analysis Branch

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Diann Sims, Chief

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# ..**~** Science Information and Analysis Branch Timothy Kiely, Chief

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## VV\_ v · \ Biological and Economic Anal s Division ( 0 P) Carissa Cyran, Chemical ReviewManager Risk Management and ImplementationBranch 1 Pesticide Re-evaluation Division (7508P) 

### Product Review Panel date: March 27,2013 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 offluthiacet-methyl and stakeholders including users ofthe chemical, registrants ofthe chemical, and the general public. This document builds upon the data already provided inthe usage and 1label 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 20,2013. Fluthiacet-methyl was first registered inthe United States in 1999. This herbicide belongs to the thiadiazole family. According to the WSSA (Weed Science Society ofAmerica) mechanism of action classification, this herbicide belongs to group 14. The mechanism ofaction ofthis group ofherbicides is inhibition ofthe enzymeprotoporphyrinogen oxidase (PPO) which leads to the degradation ofcell membranes. This causes browning and necrosis ofleaftissue and shortly after the herbicide application, leaves ofsusceptible plants will turn yellow to brown and die. Fluthiacet-methyl is currently registered as a preplantbum-down and post-emergence herbicide for the control ofbroadleafweeds in soybeans and corn, including field corn, sweet corn, and popcorn. Also, FMC Corporation has proposed several newuse sites (dry shelledpeaand beans except soybean, and cereal grains exceptrice) to be added to the fluthiacet product label (Federal Register, 2013). Also, fluthiacet-methyl is applied as a broadcast application for desiccation and defoliation ofcotton before harvesting. According to the product label, this herbicide canbe used to suppress several broadleafweeds that have developed resistance to glyphosate. HISTORY OFBEAD ASSESSMENTS FORFLUTIDACET -METHYL A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2012 whichprovides percent crop treated for corn, cotton, soybeans, and sweet corn. Forall these crops, the percent crop treated with fluthiacet-methyl was quite low (less than 2.5%). No other BEAD assessmentwas conducted recently. COMMON FORMULATIONS AND APPLICATION METHODS Fluthiacet-methyl is formulated as wettable powder, emulsifiable concentrate, and water soluble packaging. This herbicide canbe applied as a post-emergence overthe top application, post directed orhooded treatment or as a broadcast application for desiccation and defoliation of cottonbefore harvesting. Fluthiacet-methyl is applied by ground and aerial application methods. This herbicide cannot be applied using any type ofirrigation system. USE SITES Agricultural Use Sites Fluthiacet-methyl is registered for use on corn (pop, field, and sweet), cotton, and soybeans. Non-agricultural Use Sites Fluthiacet-methyl is notregistered for any non-agricultural use sites
.

USAGE


### 2Agricultural Usage Based onprivate market usage data from 2007-2011 (the only years for which usage datahas been reported), usage averaged approximately 4,500 pounds active ingredient (a.i.) annually on approximately 1.3 million acres treated. The average a.i. rate overthis time period was 0.003 pounds a.i./acre. Figure 1, whichpresents fluthiacet-methyl usage inpounds a.i. overthe 2007- 2011 timeframe, shows that agricultural usage has substantially increased since 2007. Figure 2 presents total areatreated in acres over the same timeframe (Proprietary Data, 2007-2011). As noted for totallbs applied, agricultural acreage treated with fluthiacet-methyl has also substantially increased since 2007.

2007 2008


### Source: ProprietaryData, 2007-2011 2009 Years 2010 2011



### FIGURE 2. Fluthiacet-methyl TotalArea Treated in Acres (2007-2011)
33000000 

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0 2007 2008 2009 2010 2011 Years 

### Source: Proprietary Data, 2007-2011 Table 1 shows the crops with the highest use offluthiacet-methyl from 2007-2011. Soybean was the crop with the highest use inthis timeframe with approximately 73 percent ofall pounds a.i. applied, followed by com (18%) and cotton (9%). Table 2 shows the states withthe highest use offluthiacet-methyl as a percent oftotal pounds a.i. applied withNebraska (17%), Missouri (16%), and Iowa (14%) accounting for approximately halfofall use. 

### TABLE 1. 

### Cropswith Highest Use ofFluthiacet-methyl- Percent ofTotal Lbs. Applied, TotalAcres Treated, and Average Application Rates from 2007 to 2011 Crop %TotalLbs A.I. %Total Average Annual Applied Acres Application Rates Treated (1.-bs A.I./A) Soybeans 73% 73% 0.003 Com 18% 18% 0.003 Cotton 9% 9% 0.003 

### Total 100% 100%

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### TABLE 2. States with Highest Use ofFiuthiacet-methyl- Percent ofTotalLbs. Applied, TotalAcres Treated, and Average Application Rates from 2007 to 2011 State %TotalLbs A.I. %Total Applied Acres Treated Nebraska 17% 18% Missouri 16% 15%

Iowa 14% 15% Illinois 11% 11% Minnesota 8% 8% Texas 7% 7% Other* 27% 26% 

### Total 100% 100% *other states mclude North Carolma, Kansas, South Dakota, South Carolina and 15 other states. 

### Source: ProprietaryData, 2007-2011 Agricultural Usage by Crop Reporting District 

### Average Annual Application Rates (LbsA.I./A) 0.003 0.004 0.003 0.003 0.003 0.003 0.003

Another measure ofusage is the use intensity. In this analysis, the use intensity is expressed as the pounds a.i. applied per 1000 acres ofland in farms. This differs from the application rate, whichis expressed as the pounds a.i. applied pertreated acre. The average application rate of 0.003 lb a.i. per acre implies a rate of3 lbs a.i. per 1000 treated acres. The maximum use intensity observed is about 0
.22 lbs. a.i. per 1000 acres offarmland. Figure 3 spatially represents fluthiacet-methyl usage by crop reporting district for 2007-2011.

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### Figure 3. Fluthiacet-Methyl Use Intensity by Crop Reporting District (2007- 2011)

Average Pounds Per 1,000Acres of Farmland

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- 0.046- 0
.081 0
.082-0
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This is a map ofagricultural pesticide usage at the Crop Reporting District (CRD) level prepared by BEAD for use in the Environmental Fate and Effects Division documents. These maps are used to help visualize where the pesticide being considered is most likely to be used and can be helpful in scenario selection and placing the exposure assessment in context. CRDs are boundaries created by USDA NASS which are aggregates ofcounties. Pesticide usage is displayed as average pounds (for the years 2007-2011) per 1,000 acres offarm1and in a CRD to normalize for the variation in farmland between CRDs
. Farmland acreage was obtained from USDA (2007)
. Farmland or "land in farms" is defined as follows: The acreage designated as "land in farms" consists primarily ofagricultural land used for crops, pasture, or grazing. It also includes woodland and wasteland not actually under cultivation or used for pasture or grazing, provided it was part of the farm operator's total operation. Large acreages of woodland or wasteland held for nonagricultural purposes were deleted from individual reports during the edit process. Land in farms includes CRP, WRP, FWP, and CREP1 acres. Land in farms is an operating unit concept and includes land owned and operated as well as land rented from others
. Land used rent free was reported as land rented from others. All grazing land, except land used under government permits on a per-head basis, was included as "land in farms" provided it was 1 CRP: Conservation Reserve Program; WRP: Wetland Reserve Program; FWP: Farmable Wetlands Program; CREP: Conservation Reserve Enhancement Program 

### 6part of a farm or ranch. Land under the exclusive use of a grazing association was reported by the grazing association and included as land in farms. All land in American Indian reservations used for growing crops, grazing livestock, or the potential of grazing .livestock was included as land in farms. Land in reservations not reported by reservation, individual American Indians or nonNative Americans was reported in the name ofthe cooperative group that used the land. In many instances, an entire American Indian reservation was reported as one farm (USDA, 2007). Usage is based on private market surveys ofpesticide use in agriculture (Proprietary Data, 2007-2011). 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 ofpesticide 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. This map displays ratio data (i.e
., average pounds per 1,000 acres offarmland) summarized at a very highlevel. Readers are strongly cautioned against trying to over interpret the map without examination of the underlying data. The underlying data may explain some ofthe many reasons that a Crop Reporting District may have a high value for a particular active ingredient such as significant acreage (compared with the CRD as a whole) ofa crop or crops with a high application rate and frequency ofapplication. The reader should pay particular attention to the figure legends and realize that a map prepared for a particular chemical is not directly comparable to a map prepared for a different chemical. Scale and units of measurement do matter and may be different between maps. Sources: Proprietary Data. 2007-2011; USDA, 2007. Census ofAgriculture. Online: http://www.agcensus.usda
.gov/Publications/2007/index.asp
. BIOLOGICAL ASPECTS RELEVANT TO FLUTHIACET-METHYL Fluthiacet-methyl is currently registered as a preplant bum-down and post-emergence herbicide for the control ofbroadleafweeds in soybeans and com, including field com, sweet com, and popcorn. Use offluthiacet-methyl as a tank-mixed partner with glyphosate improves the speed of weed control by rapid desiccation ofweeds presentin the crop production fields (CadetTM Product Label, 2013). In addition, fluthiacet-methyl is applied as a broadcast application for desiccation and defoliation ofcotton before harvesting
. Major weed species controlled by fluthiacet-methyl are spurred anoda (Anoda cristata), burcucumber (Sicyos angulatus), spreading dayflower (Commelina diffusa), Jimsonweed (Datura stramonium), common lambsquarters (Chenopodium album), velvet leaf(Abutilon theD_£hrasti), pigweed spp. (Amaranthus spp.), and wild buckwheat (Polygonum convolvulus) (Cadet Product Label, CDMS, 2013)
. Fluthiacet-methyl belongs to the thiadiazole group ofherbicides. According to the WSSA classification ofmechanism ofaction ofherbicides, fluthiacet-methyl belongs to group 14. The mechanism ofaction ofthis group ofherbicides is inhibition ofthe enzyme protoporphyrinogen oxidase (PPO). Inhibition ofthis enzyme causes the release ofprotoporphyrinthroughout the plant cell and in the presence oflight, singlet oxygen is produced. Singlet oxygen damages the cell membranes causing a rapid death ofplant cells. Inthe United States, common waterhemp (Amaranthus tuberculatus) biotypes withresistance to mechanism ofaction offluthiacet-methyl 7have been reported in Kansas, Illinois, and Missouri (weedscience.org, 2013). Inaddition, common ragweed (Ambrosia artemisiifolia) biotypes with resistance to the mechanism ofaction ofPPO herbicides have been reported in Delaware and Ohio (weedscience.org, 2013). Therefore, recommended herbicide resistance management strategies should be adopted to minimize this problem (WSSA, 20112). Glyphosate is a widely used herbicide in major crops such as com and soybean in the United States. Many weed species have developed resistance to glyphosate due to the extensive use of this herbicide, especially in genetically modified glyphosate resistant crops. According to the product label, fluthiacet-methyl can be 

### tank mixed with other compatible herbicides to broaden the spectrum ofbroadleafweed control and suppress glyphosate resistant weeds such as kochia (Kochia scoparia) and pigweeds (Amaranthus spp.). This may have contributed to the observed increase oftotal acreage treated with fluthiacet-methyl since 2007 (Figure 2). ROLE OF FLUTHIACET-METHYL Fluthiacet-methyl is an herbicide registered for weed control in com and soybeans. Also, fluthiacet-methyl is applied as a desiccation treatment for defoliation ofcotton before harvesting. The usage data shows a marked increase in use after 2007. The recent upswing in usage onthese crops could indicate that this herbicide is becoming a more important tool for weed management in some areas. However, more information, such as target pest and price and availability of alternatives would be necessary to fully understandthe role offluthiacet-methyl in pest management. INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK ON FLUTHIACET-METHYL Any data or information onthe importance offluthiacet-methyl for pestmanagement such as benefits ofthis chemical overthe alternatives, niche uses, and its use in resistance management, may be useful for BEAD's future assessments. REFERENCES Agro News. 2011. FMC acquires herbicide fluthiacet-methyl from two Japanese firms. http://news.agropages.com/News/NewsDetail---2528.htm
. Accessed onFeb. 8, 2013. CadetTM Product Label, FMC Corporation. Agricultural Products Group. 2011. http://www.cdms.net/ldat/ld8SC008.pdf
. Accessed onJan. 15, 2013. Federal Register. 2013. Applications for NewUses.https://www.federalregister.gov/articles/2012/01/31/2012-2039/pesticide-products-receipt-ofapplications-to-register-new-uses
. Accessed onApril 9, 2013. International Survey ofHerbicide Resistant Weeds. 2013. http://www.weedscience.org/summary/MOASummary.asp
. Accessed onMarch 8, 2013. Accessed onFeb. 25, 2013. 8Proprietary Data. 2007-2011. USDA, 2007. Census ofAgriculture. Online: http://www.agcensus.usda.gov/Publications/2007/index.asp
. Accessed on Feb. 12, 2013. Weed Science Society ofAmerica (WSSA). 2012. Reducing the Risks ofHerbicide Resistance: BestManagement Practices and Recommendations. http://www.wssajoumals.org/doi/pdf/l0.1614/WS-D-11-00155.1
. Accessed on May 9, 2013.



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