UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAR 13 2014 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

BEAD Chemical Profile (BCP) for Registration Review: Triclopyr 

Case(116001, 116002, 116004) 

Sunil 

Biological 

Ratnayak

Analysis 

e, Biologist 

Branch 

~ \_ ~ . ~ ~ \ ~ 

Sepehr 

Science 

Haddad, 

Information 

Environmental 

and Analysis 

Protection 

Branch 

Specialist h./~ 1 

Stephen Smearman, Economist 

Economic Analysis Branch 

Biological and Economic Analysis Division (7503P) 

Amet Jones, Chief /.) 11)~~ Biological Analysis Branch ~ 

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

Timothy Kiely, Chief ~ 

Economic Analysis Branch \J. ) ~ Biological and Economic Analysis Divisi 3P) 

Steve Snyderman, Chemical Review Manager 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: January 15, 2014 
SUMMARY 

Triclopyr was first registered in the United States as an herbicide in 1979 (USEP A, 1998). This 

is a systemic herbicide that belongs to the pyridine carboxylic acid family and it is used as a 

post-emergence herbicide to control annual and perennial broadleaf weeds and woody plant 

species in many agricultural and non-agricultural use sites. Triclopyr acts like a plant growth 

regulator by mimicking natural plant growth hormones (auxins). According to the Weed Science 

Society of America (WSSA) mechanism of action of herbicides, triclopyr belongs to the Group 4 

herbicides (synthetic auxins). Applications oftriclopyr at effective rates causes uncontrolled cell 

division and disorganized plant growth that leads to plant death. 

Based on private market usage data from 1998-2012, usage averaged approximately 1.3 million 

pounds acid equivalent (a.e.) applied annually on approximately 2.75 million acres treated. The 

major agricultural use sites are pasture and rice which account for approximately 98 percent of 

all agricultural usage. 

INTRODUCTION 

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

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

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

usage data for triclopyr to describe the role of this chemical in pest management. Additional 

information on use is available in the triclopyr LUIS Label Data Report. 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 

Triclopyr registered agricultural use sites include: alfalfa, almonds, apples, asparagus, beans, 

beech nut, blackberries, brazil nut, cashews, chestnuts, cole crops, citrus trees, conifer release, 

Christmas tree plantings, corn (field, pop, and sweet), flax, hazelnuts, lentils, macadamia nuts, 

mint, oats, onions, pastures, peas, pecans, pistachio nuts, potatoes, rice, safflower, sorghum, 

soybeans, strawberries, sugar beets, sunflower, vegetable crops, walnuts, wheat, and yucca as 

well as acreage enrolled in the conservation reserve program (CRP). 

Non-Agricultural Use Sites 

Registered non-agricultural use sites of triclopyr include: agricultural buildings, airports, cabins, 

camp sites, canals, domestic dwellings, patios, fencerows, forest lands, industrial sites, 

ornamental woody plants, ornamental lawns, ornamental turf, ornamental trees, farm buildings, 

aquatic areas, wetlands, rights-of-way, and recreational areas. 

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FORMULATIONS AND APPLICATION METHODS 

Triclopyr formulations include soluble concentrate, emulsifiable concentrate, liquid (pressurized 

and ready-to-use), granular, wettable powder, and pelleted. Ground and aerial are the application 

methods of this chemical. 

HISTORY OF TRICLOPYR and BEAD PRODUCTS 

Triclopyr was first registered in 1979 as an herbicide for control of broadleaf weeds and woody 

plants in non- crop and forestry areas. Triclopyr was reregistered in 1997. A Screening Level 

Usage Analysis (SLUA) was prepared by BEAD .for this chemical in 2013 that provides the 

percent crop treated for 10 crops for which usage data was available (alfalfa, apples, corn, 

fallow, hazelnuts, oranges, pasture, pecans, rice and wheat). For triclopyr, based on the SLUA, 

there are two agricultural sites with the greatest number of pounds used. The sites are pasture 

with nearly 90% of the use followed by rice. 

Benefits Assessments- A search of BEAD's Official Records data base for BEAD benefits 

assessments specifically for triclopyr did not find any records of prior BEAD assessments in the 

last 10 years. 

Emergency Exemptions- a search of BEAD's Official Records did not find any Section 18s 

requests for triclopyr in the last 1 0 years. Emergency exemptions may indicate that there is a 

need for a particular chemical that is not registered for use on a particular site. Approval of an 

emergency exemption request may yield information through the emergency exemption process 

about a particular chemical's importance or value that is not found in other EPA records. 

However, a lack of Section 18 assessments by BEAD does not specifically indicate the relative 

importance of the chemical. 

USAGE 

Agricultural Usage 

Based on private market usage data from 1998-2012, usage averaged approximately 1.3 million 

pounds acid equivalent (a.e.) applied annually on approximately 2.75 million acres treated. The 

average a.e. rate over this time period was 0.475 pounds a.e./acre. Figure 1 presents triclopyr 

usage in pounds a.e. and total area treated in acres over the 1998-2012 timeframe (Proprietary 

Data, 1998-20 12). Figure I shows that over this time period in terms of pounds applied and 

acres treated there has been a steady decline in use. 

Page 3 
FIGUREl. Triclopyr Usage in Pounds Acid Equivalent & Total Area Treated in Acres 

(1998-2012) 

4500000 

0 

?J'b ?Jo, ~<;) ~"" ~"' ~~ ~ ~" ~Co sY ~'b ~0) ~<;) ~"" ~"' ""o; ""o; "'cs ,_cs ,_cs ,_cs ,_cs ,_cs ,_ cs ,_ cs ,_cs ,_cs ,_<::> ,_<::> ,_<::> 

Years 

Source: Proprietary Data, 1998-2012 

-+-Pounds AE 

Tot<~ I Are<t Tre<tted 

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

Applied 2003-2007 and 2008-2012) 

2003-2007 2008-2012 

Average annual= l million lbs/yr Average annual= 1.2 million lbs/yr 

Crop %Lbs Crop %Lbs 

Pasture 90% Pasture 89% 

Rice 8% Rice 9% 

Pecans l% Fallow l% 

Oranges 1% Oranges 1% 

Source: Propnet.ary Data, 2003 -2012. 

Table 1 shows that the crops with the most pounds applied during both the 2003-2007 and 2008-

2012 timeframes have been pasture and rice accounting for approximately 98 percent of total 

pounds applied. The average annual usage in pounds has increased approximately 20 percent 

from 1 million lbs/year to 1.2 million pounds per year in the 2008-2012 timeframe. 

Page 4 
Table 2. Comparison of States with Highest Use of Triclopyr- Percent of Total Lbs. 

Applied (2003-2007 and 2008-2012) 

2003-2007 2008-2012 

Average annual= I million lbs/yr Average annual=l.2 million lbs/yr 

State % Lbs State %Lbs 

Texas 28% Texas 24% 

Oklahoma 15% Oklahoma 18% 

Arkansas 9% Arkansas 12% 

Alabama 6% Missouri 8% 

Missouri 6% Georgia 5% 

Other* 36% Other* 33% 

*Other States in the 2003-2007 and 2008-201 2 timeframes include Florida, Tennessee, California, 

Kansas, Virginia, Louisiana and more than 20 other states. 

Source: Propnetary Data, 2003 -2012 

As shown in Table 2, Texas, Oklahoma and Arkansas were the top three states with the highest 

use of triclopyr in both time frames accounting for more than 50 percent of total pounds applied. 

Application Rates 

The average a. e. rate for the top crops in terms of pounds a. e. applied was the highest for pasture 

at 0.50 lbs a.e./acre and the lowest for rice at 0.19 lbs a.e./acre as shown in Table 3. 

T a e bl 3 . T nc . I opyr u se on T C op rops: A vera~ e A . . E R a t e, 2008 -2012 

Annual Average Annual Average A vg. A.E. Rate (lbs Crop Pounds Total Acres a.e./acres) Treated* 

Pasture 872,000 1, 719,200 0.50 

Rice 88,290 453,500 0.19 

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

Source: Proprietary Data, 2008 -2012 

Geographic Distribution of Triclopyr Use 

Figure 2 provides a very broad geographical view of the average annual amount (in pounds) of 

triclopyr 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 ail A), 

therefore, the map may show areas of high use intensity that do not correspond to the states listed 

in Table 2 since those states (such as Texas, Oklahoma and Arkansas for example) are the states 

with the highest use oftriclopyr based on pounds active ingredient applied. 

As shown in the map, the southern states especially Florida, Georgia, Alabama, Arkansas and 

Page 5 
Oklahoma, in addition to Texas and California, depict a high use intensity of acres treated with 

triclopyr. Please see Appendix I for a more detailed explanation of the information presented on 

the map. 

FIGURE 2. Triclopyr Usage by State (2008 -2012) 

Pounds Active Ingredient 

per 1.000 Crop Acres Grown 

0 No0ala 

<03 

. 0.3 · 0.6 

. 0.7 ·1 9 

. 2.0·6-9 

- >69 

Non-Agricultural Usage 

Most available non-agricultural usage data for triclopyr is limited and dated. The only reported 

data available are for the years 2002, 2004, 2006 (for landscaping, lawn care operators, golf 

courses, institutional turf, nursery/greenhouses, and turf farms) aquatic uses and consumer lawns 

for 2005, and the most recent for consumer lawns in 2011 as shown in Table 4. Total nonagricultural usage between 2002 and 2006 appears to have declined for golf courses, turf farms, 

and landscape, but increased for nursery/greenhouse; however, more recent data (post-2006) are 

not available to determine if this trend has continued since only one category of non-agricultural 

usage (consumer lawns) was available for 20 11. 

Page6 
Table 4. Triclopyr Non-Agricultural Usage (Pounds A.E) (2002-2011 

Site 2002 2004 2005 2006 2011 

Golf Courses 76,000 31,300 NIA 20,000 N/A 

Institutional Turf 76,500 61 ,200 NIA 63,300 N/A 

Landscape 319,000 64,100 NIA 84,700 NIA 

Lawn Care Operators 113,000 80,800 NIA 90,700 NIA 

Nursery /Greenhouse 1,500 3,750 NIA 11 ,950 NIA 

Turf Farms 34,350 100 NIA 12,650 NIA 

Aquatic Areas NIA NIA 44,000 NIA NIA 

Consumer Lawns NIA N/A 152,000 N/A 100,000 

N/A= Not Available 

Source: Proprietary Data 2002-2011 

BIOLOGICAL ASPECTS RELEVANT TO TRICLOPYR 

Triclopyr is a selective and systemic herbicide that belongs to the pyridine carboxylic acid 

family. Aminopyralid, fluroxypyr, and clopyralid are other herbicides that belong to the pyridine 

carboxylic acid family. Triclopyr is applied as a post-emergence treatment to control annual and 

perennial broad leaf weeds and woody plant species in many agricultural and non-agricultural use 

sites. According to the Weed Science Society of America (WSSA) mechanism of action 

classification, triclopyr belongs to the group of synthetic auxins (Group 4) (WSSA, Undated). 

These herbicides act like natural plant growth regulators by mimicking natural plant growth 

hormones. Triclopyr is absorbed by the plants through foliage and roots and translocated 

throughout the plant (Herbicide Handbook, 2003). Application of herbicides belonging to group 

4 causes uncontrolled cell devision leading to the death of susceptible plants It has been reported 

that biotypes of 8 weed species have developed resistance to triclopyr in the United States (Heap, 

Weedscience.org,Undated Online publication). 

ROLE OF TRICLOPYR IN PEST MANAGEMENT 

Triclopyr can be applied for controlling woody plants, annual and perennial broad leaf weeds, in 

forest areas, grass pastures, range lands, conifer release programs, and conservation reserve 

programs (Herbicide Hand Book, 2007). During the period from 2008 to 2012 a higher 

percentages of average annual use (lbs a.i.) of triclopyr were observed on pasture (89 %) and in 

rice production (9 %) (Tablel). The higher usage of this herbicide on pasture indicates that 

triclopyr is an important herbicide for management of unnecessary woody species, shrubs, and 

other broadleaf weeds in pasture lands. In rice production, triclopyr is used to control many 

broadleafweed species including, momingglory (Ipomoea spp.), Hempsesbania, (Sesbania 

exaltata), northern jointwetch (Aeschynomene virginia) and Texas weed (Caperonia palustrus). 

In rice production, to achieve a broader spectrum of weed control triclopyr can be tank mixed 

with other herbicides such as propanil (Street et al., undated) 

In terms ofthe percent crop treated, all sites in the SLUA had values of less than 1 percent, 

except for pasture with less than 2.5 percent, and rice at 15 percent of crop treated. This 

indicates that triclopyr provides benefits to the growers of these crops especially pasture and rice. 

Page 7 
DATA NEEDS 

The Agency currently does not have complete information for triclopyr. Obtaining the following 

information may improve future assessments conducted by the Agency related to the use and 

importance oftriclopyr. 

Agricultural Use 

BEAD proprietary databases do not contain survey data on registered agricultural sites 

such as cashews, flax, lentils, mint and macadamia nuts. Usage data such as pounds a.i. 

applied and application rate information would be useful if available 

Non Agricultural Use 

Except for recent usage data on consumer lawns in 2011, BEAD does not have recent 

(post-2006) data on non-agricultural usage for the following: golf courses, institutional 

turf, landscaping, nursery/greenhouses, and turf farms. Usage data such as pounds a.i. 

applied and application rates would be useful if available. 

Page 8 
REFERENCES 

Alligare Triclopyr 4, Specimen Label. 2013. Alligare, LLC. 13 N. 81h Street, Opelika, AL 36801. 

http://www.alligare.com/assets/pdfffRICLOPYR 4 LABEL.pdf 

BEAD, 2013. Triclopyr Screening Level Usage Analysis. Biological and Economic Analysis 

Division, Office of Pesticide Programs, US Environmental Protection Agency. 2013 

Heap, I. (Undated) The International Survey of Herbicide Resistant Weeds. Online. Internet. 

Tuesday, February 11,2014. Available www.weedscience.org . . Accessed Date. Jan. 8, 

2014. 

Herbicide Handbook. 2003. Guidance on the use of herbicides on nature conservation sites, 

Sections 1-4. Triclopyr. Pp 107-108. 

http:/lpublications.naturalengland.org.uk/publication/68019. 

Accessed Date. Nov. 18, 2013. 

Proprietary Data, 2002-2011 (non-agricultural usage data) 

Nickerson, C., R. Borchers, E. A. and F. Carriazo. 2011. Major Uses of Land in the United 

States, 2007. USDAIERS. Economic Information Bulletin Number 89. 

Proprietary Data. 1998-2012. (pesticide agricultural usage data) 

Street, J., Allen R. L., and E. M. Johnston. (No Date). Weed Control in Rice with Propanil and 

Triclopyr Combinations. Delta Research and Extension Center. On line Publication. 

Available at: http://msucares.com/pubs/bulletins/b 1 035.pdf. Accessed Date. Feb. 10, 

2014. 

US Census. 2012. Statistical Abstract of the United States 2012. Table 358. 

USEP A. 1998. Registration Eligibility Decision. Triclopyr. 

http://www.epa.gov/oppsrrd 1 /REDs/27 1 Ored.pdf. 

Accessed Date. Nov. 25, 2013. 

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

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

USDA, 2006-20 I 0. 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. 

Page 9 
USDA, 2007. Census of Agriculture. (for Land in Farms data). Available at: 

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

WSSA(Weed Science Society of America, Undated). Summary of Herbicide Mechanism of 

Action. Weed Science Society of America. Available at: http://wssa.net/wpcontent/uploads/WSSA-Mechanism-of-Action.pdf . Accessed Date, Jan. 6, 2014. 

Page 10 
APPENDIX I. 

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 acid equivalent 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./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, {dates}). 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 acid equivalent 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 acid equivalent being used. 

The denominator (1,000 Acres of land 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 

• Permanentpasture 

• 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 of the land being 

managed for agricultural purposes. 

Page 11 
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. 

Page 12