UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAY 2 3 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

BEAD Chemical Profile (BCP) for Registration Review: Triallate (078802) 

Bill 

Biological 

Phillips

Analys

, Ph.D

i

.

s 

, Agronomis

Branch 

t 

tff)!?/ ~ 

<. ,;/ t.t 

Jihad . Alsadek, Ph.D., Economist . J ,.,.-v 

, 

~fA A/-'~ 

Science Information and Analysis Branch 

Stephen Smearman, Economist ~. .. 1 J 

E

Biological 

conomic Analysis 

and Economic 

Branch 

Analysis Divi

~~ 

sion (7503P) 

Arnet Jones, Chief V. -.IIJ~ Biological Analysis Bran~y [/ 

Diann Sims, Chief 

Science Information and Analysis Branch g 

Timothy Kiely, Chief f.+ \JJ\_ 

Economic Analysis Branch "'-! ) 

Biological and Economic Analysis Division (7503 ) 

Katherine StClair, Chemical Review Manager 

Risk Management and Implementation Branch 4 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: May 14,2014 

SUMMARY 

Triallate was first registered as a pesticide in the U.S. in 1961 (US EPA, 200 I) and a Registration 

Eligibility Decision (RED) document was published in 2000. 
As a member of the Weed Science Society of America group eight herbicides, triallate has the 

mechanism of action of inhibiting the synthesis of fatty acids and lipids. 

Triallate is used to control persistent grass weeds such as wild oats (Avenafatua) in barley and 

wheat. Weeds like wild oats are of particular importance since they reduce crop yields and can 

be harvested along with the crop and is considered a contaminate when brought to market. In 

wheat and barley, triallate can be used preplant incorporated thus providing control prior to 

emergence of the weed. By controlling wild oats prior to emergence, competition between the 

weed and crop is avoided and it keeps the seed from being harvested and contaminating the 

harvested crop grain. 

Because there is a 12 month restriction for planting any crop other than those currently registered 

for its use, and because triallate does not control emerged weed, there may be an advantage to 

using postemergence herbicides for controlling grass weeds. Because of the large decrease in 

usage during the time period from 1998 to 2012, BEAD has determined that the utility of this 

herbicide has lessened and thus may have been displaced by another herbicide or method of 

weed control. 

Based on private market usage data from 1998-2012, usage averaged approximately 874,000 

pounds active ingredient (a.i.) applied annually on approximately 792,000 acres treated. The 

average a.i. rate over this time period was 1.10 pounds a.i. /acre. The use of triallate between the 

years 2008 and 2012 averaged less than 160,000 lbs. a.i. and the percent crop treated was less 

than 2.5 percent for all crops. There are no reported usage data for non-agricultural use sites. 

The relatively low percent crop treated on these crops indicate low benefits, or at the very least, a 

low reliance on triallate to control weeds in these crops. 

INTRODUCTION 

The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an 

overview of the pest management roles and quantitative usage information for triallate. The 

BCP includes summaries of previous BEAD products and available public and/or private use and 

usage data for triallate to describe the role of this chemical in pest management. Information 

provided in this BCP may be used by stakeholders (e.g., users and registrants), OPP risk 

assessors, OPP risk managers, and the general public during the Registration Review process of 

this pesticide. 

USE SITES 

Agricultural Use Sites 

Triallate's registered agricultural use sites include: Bermudagrass (grown for seed or hay), dry 

beans and peas, green peas, lentils, barley, spring wheat, triticale and sugar beets. 

2 
FORMULATIONS AND APPLICATION METHODS 

Triallate is formulated as emulsifiable and granular. Depending on the crop, triallate may be 

applied before or after planting, either by ground or aerial equipment. Application is typically 

made either in the fall or in the spring, before targeted weed species germinate. 

HISTORY OF TRIALLATE and BEAD PRODUCTS 

Triallate is an herbicide registered for use in the U.S. since 1961 and a RED was published in 

2000. A search of the BEAD database for previous BEAD products for triallate indicates that 

there are no records of prior BEAD benefits assessments or emergency exemption requests for 

triallate in the last 10 years. Note that a lack of emergency exemption requests does not indicate 

the relative importance of the chemical. 

A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 

that provides percent crop treated for barley, dry beans/peas, green peas, sugar beets and wheat. 

For triallate, the agricultural sites with the greatest number of pounds used were for wheat 

followed by barley. In terms of the percent crop treated, all crops are less than 2.5 percent 

treated. There has been a significant decline in both the total pounds of triallate used and the 

total area treated over the reported use period. In addition, the relatively low percent crop 

treated for triallate on the top crops indicate low benefits, or at the very least, a low reliance on 

triallate to control weeds in these crops. 

USAGE 

Agricultural Usage 

Based on private market usage data from 1998-2012, usage averaged approximately 874,000 

pounds active ingredient (a.i.) applied annually on approximately 792,000 acres treated. The 

average a.i. rate over this time period was 1. 1 0 pounds a.i. /acre. The use of triallate decreased 

by 92 percent since 1998. Figure 1 presents triallate usage in pounds a.i. over the 1998-2012 

timeframe. Figure 2 presents total area treated in acres over the same timeframe (Proprietary 

Data, 1998-2012). 

3 
FIGURE 1. Triallate Usage in Pounds Active Ingredient (1998-2012) 

3.500,000 

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Source: Proprietary Data, 1998-2012 

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Years 

FIGURE 2. Triallate Total Area Treated in Acres (1998-2012) 

3,000,000 

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Source: Proprietary Data, 1998-2012 

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4 
Table 1. Comparison of Crops with Highest Use of Triallate- Percent of Total Lbs. 

Applied (1998-2002 and 2008-2012) 

1998-2002 2008-2012 

Average Annual Usage = 2,000,000 lbs/yr Average annual= 156,000 lbs/yr 

Crop %Lbs Crop %Lbs 

Spring Wheat 54 Barley 35 

Barley 32 Spring Wheat 32 

Winter Wheat 8 Dry Beans/Peas 21 

Dry Beans/Peas 3 Winter Wheat 11 

Other 3 Other I 

Source: Propnetary Data, 1998 -2012. 

Table 2. Comparison of States with Highest Use of Triallate- Percent of Total Lbs. 

Applied (1998-2002 and 2008-2012) 

1998-2002 2008-2012 

Average Annual Usage = 2,000,000 lbs/yr Average Annual Usage= 156,000 lbs/yr 

State %Lbs State %Lbs 

Montana 47 Washington 42 

North Dakota 27 Montana 30 

Idaho 12 Idaho 20 

Washington 11 North Dakota 4 

Other 3 Other 4 

Source: Proprietary Data, 1998 -2012 

The major agricultural use oftriallate during the 1998-2002 and 2008-2012 time frames are 

spring wheat and barley, with use contracted in Montana, North Dakota, Idaho and Washington. 

Overall use has declined over 90 percent between 1998-2002 and 2008-2012 with similar 

declines in most states. 

The average annual a.i. rate for the top crops was the highest for barley at 1.109 lbs. a.i./acre and 

the lowest for dry beans/peas at 0.963 lbs. a.i./acre as shown in Table 3. 

Application Rates 

T a bl e 3 . T raa . II a e t U se on T C op rops: A verage An nua IAI .. R ate, 2008 2012 - Average Annual Average Annual Avg. Annual A.l. 

Crop Pounds A.I. Rate (lbs 

Applied Total Acres Treated* a.i.lacres) 

Barley 54,533 49,177 1.109 

Spring Wheat 50,567 49,441 1.023 

Dry Bean/Peas 33,139 34,397 0.963 

Winter Wheat 17,968 17,889 1.000 

*Total Acres Treated sums all acres treated for a crop, including those acres that receive multiple treatments. 

Source: Proprietary Data, 2008 -2012 

5 
Geographic Distribution of Triallate Use 

Pounds Active Ingredient 

per 1.000 Crop Acres Grown 

CJNoOata 

0 <0,32 

. 0.32 · 0.59 

- 0.60 - 5.50 

- >5.50 

Figure 3. Annual average agricultural use intensity of TriaUate (2008-2012). 

The map included herein is primarily for the use of the risk assessors in the Environmental Fate 

and Effects Division. The map provides a very broad geographical view of the average annual 

amount (in pounds) of the active ingredient applied per 1,000 acres of crop acres grown. These 

data are included in the maps because risk assessors are interested in the amount of a pesticide 

used across agricultural land. The calculated values presented in the map are not equivalent to 

an application rate (lb. a.i. /A). 

The data used to make these maps have several limitations. Any interpretation of the maps 

should consider the underlying data and the associated limitations carefully. 

The numerator (annual average pounds applied) is based on private market surveys of pesticide 

use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys 

cover about 60 crops and are targeted in states that produce the majority of the crop. Although 

the surveys capture most of the use of a particular active ingredient in agriculture, there are 

several limitations to these surveys. 

6 
• States with minor production of a surveyed crop are not sampled 

• Not all types of pesticides are surveyed in every crop in every year 

• Many specialty crops with very small acreages are not included in the survey 

The result of these limitations is that states that show no usage may actually have a small amount 

of the active ingredient being used. In some cases the displayed use intensity may be distorted 

because the surveyed crops and the reported pesticide usage may not accurately represent the 

actual pesticide usage on the crops produced in the state. 

The denominator ( 1,000 crop acres grown) was also obtained from the same private market 

survey database. The "Crop Acres Grown" variable represents the total acres grown in a given 

state of all of the surveyed crops. This value is independent of pesticide usage and pesticide 

registration. It is important to note that the surveyed crops (about 60) are sampled from states 

that are major producers of each crop. Therefore, there are cases where the actual crop acreage in 

a state is higher than that reported by crop acres grown in the survey because either that state 

and/or crop was not included in the survey. 

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 as 

the legend bins will likely be different. 

Non-Agricultural Usage 

There are no reported usage data for non-agricultural use sites. 

CHEMICAL AND USE CHARACTERISTICS FOR TRIALLATE 

Triallate is a preplant-incorporated herbicide that can be applied in the fall prior to the crop being 

planted or in the spring either incorporated preplant or after the crop has been planted. On 

average, this herbicide is applied only once per cropping season for barley, dry beans/peas and 

spring wheat. Triallate is used in several crops to provide preemergence control of grass weeds 

such as wild oats. 

As a member of the Weed Science Society of America group eight herbicides, triallate has the 

mechanism of action of inhibiting the synthesis of fatty acids and lipids. The mode of action 

of this herbicide is the inhibition of growth of the coleoptile (sheath covering the growing tip) 

of the newly emerging grass weeds (Senseman et al. 2007). 

ROLE OF TRIALLATE IN PEST MANAGEMENT 

Triallate is used to control persistent grass weeds such as wild oats (Avenafatua). Wild oats are 

of particular concern since this weed reduces crop grain production by competing with crops, 

7 
such as barley and wheat, for resources. In addition to competing with crops, the grain from wild 

oats is harvested along with crop grain which reduces grain quality (Pokorny 2007). The mixing 

of the weed seeds and the crop grain can result in growers paying a penalty because of the added 

cost to separate the wild oats seeds from the grain. 

The majority of herbicides that. are used to control wild oats are postemergence applied. Some of 

these postemergence herbicides provide some level of residual control. However, in wheat and 

barley crops triallate can be used preplant incorporated thus providing control prior to emergence 

ofthe weed (Warrick eta!. No date provided). By controlling wild oats prior to emergence, 

competition between the weed and crop is avoided and the continued control via the residual 

activity reduces the potential for harvested seed to contaminate the harvested crop grain. 

A drawback of using triallate is that there is a 12 month restriction for planting any crop other 

than those currently registered for its use. For this reason there may be an advantage to using the 

postemergence herbicides for controlling wild oats and other grass weeds. In addition, because of 

the large decrease in usage during the time period from 1998 to 2012, BEAD has determined that 

the utility of this herbicide has lessened and thus may have been displaced by another herbicide 

or method of weed control. 

DATA NEEDS 

The Agency currently does not have important information on triallate. Obtaining information 

on crops that are registered but our proprietary database does not survey such as lentils and 

triticale and on non-agricultural use sites such as grasses may improve future assessments 

conducted by the Agency related to the use and importance of triallate. Information on pounds 

a.i. applied, percent crop treated, application rates and where and when triallate is used. 

REFERENCES 

BEAD, 2014. Triallate Screening Level Usage Analysis. Biological and Economic Analysis 

Division, Office of Pesticide Programs, US Environmental Protection Agency. January 

14,2014 

Pokorny, M. 2007. Wild Oat (Avenafatua). Accessed at: 

http://ipm.montana.edu/cropweeds!Extension/weed%20species%20-

not%20every%20file%20is%20here-/Wild%20oat.htm 

Proprietary Data. 1998-2012. 

Senseman, S.A. (2007), Herbicide Hand Book Ninth Edition. Weed Sci. Soc. of Am. 810 E. 

101h Street, Lawrence, KS 66044-8897. U.S.A. 

8 
USDA, 2006-2010. NASS Crop Reporting Districts (shape file ofCRDs). Available at: 

http://www.ers.usda.gov/briefing/arms/resourceregions/resourceregions.htm#nass. 

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

http://www.nass.usda.gov/Data and Statistics/County Data Files/Frequently Asked 0 

uestions/county list.txt 

USDA, 2007. Census of Agriculture. Online: 

http://www .agcensus. usda.gov /Publications/2007 /index.asp. 

USDA, 2007. Census of Agriculture. (for Land in Farms data). Available at: 

http://www.agcensus.usda.gov/Publications/2007/index.asp. 

http:/ /www.epa.gov/oppOOOO 1/chem search/reg actions/reregistration/fs PC-078802 1-MarOl.pdf 

http://www.epa.gov/oppOOOO I /chem search/reg actions/reregistration/red PC-078802 1-AugOO.pdf 

Warrick, B. E. and T. Baughman. (No date provided) Wild Oat Control in Texas. Accessed at: 

http://sanangelo.tamu.edu/extension/agronomy/agronomy-publications/wild-oat-controlpublication/ 

APPENDIX A 

The map included herein primarily for the use of the risk assessors in the Environmental Fate and 

Effects Division. The map provides a very broad geographical view of the amount (in pounds) 

of the active ingredient applied per 1,000 acres of"land in farms". These data are included in the 

maps because risk assessors are interested in the amount of a pesticide used across farmland. 

Because of the definition of Land in Farms, as discussed below, the calculated values presented 

in the map are not equivalent to an application rate (lbs a.i. I A). 

The data used to make these maps have many limitations. Any interpretation of the maps should 

consider the underlying data and the associated limitations carefully. 

The smallest areas shown on the maps within each state are Crop Reporting Districts (CRD). 

CRDs are defined by USDA and each consists of multiple counties that have similar soils, 

growing conditions, and farming practices. The CRDs within many states have roughly the same 

area. Because it is not feasible to conduct an agricultural survey that samples every county in the 

United States, the use of CRDs allow for a sample to be collected that represent a much larger 

area with relatively homogeneous agricultural characteristics. 

The numerator (annual average pounds applied) is based on private market surveys of pesticide 

use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys 

cover about 60 crops and are targeted in states that produce the majority of the crop. Although 

9 
the surveys capture most of the use of a particular active ingredient in agriculture, there are 

several limitations to these surveys. 

• States with minor production of a surveyed crop are not sampled Not all types of 

pesticides are surveyed in every crop in every year 

• Many specialty crops with very small acreages are not included in the survey 

The result of these limitations is that CRDs that show no usage may actually have a small 

amount of the active ingredient being used. 

The denominator (1,000 Acres ofland in farms) was selected from the Census of Agriculture 

(USDA, 2007) to represent agricultural acreage that is actively managed and includes most of the 

areas treated with pesticides. The category "Land in Farms" is defined by the Census of 

Agriculture as being made up of four components: 

• Total cropland 

• Permanent pasture 

• Total woodland 

• Land in farmsteads, buildings, livestock facilities, ponds, roads, wasteland, etc. 

This category includes land in the various USDA conservation programs. It should be noted that 

the Census of Agriculture does not include grazing land rented (on a per-animal basis) from the 

Bureau of Land Management or Forest Service, thus it is an underestimate ofthe land being 

managed for agricultural purposes. 

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. 

10