UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAY 2 8 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 rl. . \_ 0 ~ BiologicalAnalysisBranch ~- ~~(\~~ 

Sepehr Haddad, Environmental Protection Specia!LJ Itt-~ 

;:::::-~::::alysisB M ct,JbMMI 

Economic Analysis Branch v' y I I ~\f-./ ' \1/ \ 

Biological and Economic Analysis Division (7503P) 

Arnet Jones, Chief /.) _ .A..l 

Biological Analysis Branch ~ : i 

Diann Sims, Chief I{J~OA7 .. ~ Science Information and Analysis Branch 

Timothy 

Economic Kiely, Analysis 

Chief 

Branch ~ ·, VV\_ . 1.~ v· \ 

Biological and Economic Anal s Division ( 0 P) 

Carissa Cyran, Chemical Review Manager 

Risk Management and Implementation Branch 1 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel date: March 27,2013 

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 fluthiacet-methyl and stakeholders including users of the chemical, registrants of the chemical, 

and the general public. This document builds upon the data already provided in the usage and 

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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 20,2013. 

Fluthiacet-methyl was first registered in the United States in 1999. This herbicide belongs to the 

thiadiazole family. According to the WSSA (Weed Science Society of America) mechanism of 

action classification, this herbicide belongs to group 14. The mechanism of action of this group 

ofherbicides is inhibition of the enzyme protoporphyrinogen oxidase (PPO) which leads to the 

degradation of cell membranes. This causes browning and necrosis of leaf tissue and shortly 

after the herbicide application, leaves of susceptible plants will turn yellow to brown and die. 

Fluthiacet-methyl is currently registered as a preplant bum-down and post-emergence herbicide 

for the control of broadleaf weeds in soybeans and corn, including field corn, sweet corn, and 

popcorn. Also, FMC Corporation has proposed several new use sites (dry shelled pea and beans 

except soybean, and cereal grains except rice) to be added to the fluthiacet product label (Federal 

Register, 2013). Also, fluthiacet-methyl is applied as a broadcast application for desiccation and 

defoliation of cotton before harvesting. According to the product label, this herbicide can be used 

to suppress several broadleaf weeds that have developed resistance to glyphosate. 

HISTORY OF BEAD ASSESSMENTS FOR FLUTIDACET -METHYL 

A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2012 

which provides percent crop treated for corn, cotton, soybeans, and sweet corn. For all these 

crops, the percent crop treated with fluthiacet-methyl was quite low (less than 2.5%). No other 

BEAD assessment was conducted recently. 

COMMON FORMULATIONS AND APPLICATION METHODS 

Fluthiacet-methyl is formulated as wettable powder, emulsifiable concentrate, and water soluble 

packaging. This herbicide can be applied as a post-emergence over the top application, post 

directed or hooded treatment or as a broadcast application for desiccation and defoliation of 

cotton before harvesting. Fluthiacet-methyl is applied by ground and aerial application methods. 

This herbicide cannot be applied using any type of irrigation 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 not registered for any non-agricultural use sites. 

USAGE 

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Agricultural Usage 

Based on private market usage data from 2007-2011 (the only years for which usage data has 

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 over this time period was 0.003 

pounds a.i./acre. Figure 1, which presents fluthiacet-methyl usage in pounds a.i. over the 2007-

2011 timeframe, shows that agricultural usage has substantially increased since 2007. Figure 2 

presents total area treated 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: Proprietary Data, 2007-2011 

2009 

Years 

2010 2011 

FIGURE 2. Fluthiacet-methyl Total Area Treated in Acres (2007-2011) 

3 
3000000 

I 

~ -

i 

& 

II 

~ 

I 

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 in this timeframe with approximately 73 percent of all pounds a.i. 

applied, followed by com (18%) and cotton (9%). Table 2 shows the states with the highest use 

offluthiacet-methyl as a percent of total pounds a.i. applied with Nebraska (17%), Missouri 

(16%), and Iowa (14%) accounting for approximately half of all use. 

TABLE 1. Crops with Highest Use ofFluthiacet-methyl- Percent of Total Lbs. Applied, 

Total Acres Treated, and Average Application Rates from 2007 to 2011 

Crop %Total Lbs 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 of Total Lbs. Applied, 

Total Acres Treated, and Average Application Rates from 2007 to 2011 

State %Total Lbs 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: Proprietary Data, 2007-2011 

Agricultural Usage by Crop Reporting District 

Average Annual 

Application Rates 

(Lbs A.I./A) 

0.003 

0.004 

0.003 

0.003 

0.003 

0.003 

0.003 

Another measure of usage is the use intensity. In this analysis, the use intensity is expressed as 

the pounds a.i. applied per 1000 acres of land in farms. This differs from the application rate, 

which is expressed as the pounds a.i. applied per treated acre. The average application rate of 

0.003 lb a.i. per acre implies a rate of 3 lbs a.i. per 1000 treated acres. The maximum use 

intensity observed is about 0.22 lbs. a.i. per 1000 acres of farmland. 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 

1,000 Acres of Farmland 

- <0.010 

- 0.010-0.025 

D o.o26-o.o45 

- 0.046- 0.081 

0.082-0.22 

This is a map of agricultural 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 of counties. 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 of agricultural 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 

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part 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 of the 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 of pesticide 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 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. 

This map displays ratio data (i.e., average pounds per 1,000 acres of farmland) 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 of the 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) of a crop or crops with a high application rate and frequency of application. 

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 of Agriculture. 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 of broadleaf weeds 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 of weeds present in the crop production fields (CadetTM Product 

Label, 2013). In addition, fluthiacet-methyl is applied as a broadcast application for desiccation 

and defoliation of cotton 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 of herbicides. According to the WSSA 

classification of mechanism of action of herbicides, fluthiacet-methyl belongs to group 14. The 

mechanism of action ofthis group ofherbicides is inhibition ofthe enzyme protoporphyrinogen 

oxidase (PPO). Inhibition of this enzyme causes the release of protoporphyrin throughout the 

plant cell and in the presence of light, singlet oxygen is produced. Singlet oxygen damages the 

cell membranes causing a rapid death of plant cells. In the United States, common waterhemp 

(Amaranthus tuberculatus) biotypes with resistance to mechanism of action of fluthiacet-methyl 

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have been reported in Kansas, Illinois, and Missouri (weedscience.org, 2013). In addition, 

common ragweed (Ambrosia artemisiifolia) biotypes with resistance to the mechanism of action 

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 of broadleaf weed control and suppress glyphosate resistant weeds such as kochia 

(Kochia scoparia) and pigweeds (Amaranthus spp.). This may have contributed to the observed 

increase of total 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 of cotton before harvesting. 

The usage data shows a marked increase in use after 2007. The recent upswing in usage on these 

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 understand the role of fluthiacet-methyl in pest 

management. 

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

FLUTHIACET -METHYL 

Any data or information on the importance of fluthiacet-methyl for pest management such as 

benefits of this chemical over the 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 on Feb. 8, 2013. 

CadetTM Product Label, FMC Corporation. Agricultural Products Group. 2011. 

http://www.cdms.net/ldat/ld8SC008.pdf. Accessed on Jan. 15, 2013. 

Federal Register. 2013. Applications for New Uses. 

https://www.federalregister.gov/articles/2012/01/31/2012-2039/pesticide-products-receipt-ofapplications-to-register-new-uses . Accessed on April 9, 2013. 

International Survey of Herbicide Resistant Weeds. 2013. 

http://www.weedscience.org/summary/MOASummary.asp . Accessed on March 8, 2013. 

Accessed on Feb. 25, 2013. 

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Proprietary Data. 2007-2011. 

USDA, 2007. Census of Agriculture. Online: 

http://www.agcensus.usda.gov/Publications/2007/index.asp . Accessed on Feb. 12, 2013. 

Weed Science Society of America (WSSA). 2012. Reducing the Risks of Herbicide Resistance: 

Best Management Practices and Recommendations. 

http://www.wssajoumals.org/doi/pdf/l 0.1614/WS-D-11-00 155.1 . Accessed on May 9, 2013. 

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