UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

UAY 0 5 2014 

MEMORANDUM 

OFFICE OFCHEMICAL SAFETY 

ANDPOLLUTION PREVENTION 

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Pyraflufen-ethyl 

(030090) 

FROM: 

THRU: 

Sunil Ratnayake, Ph.D., Biologist 

Biological Analysis Branch 

Jihad Alsadek, Ph.D., Economist 

Science Information and Analysis Branch _ J _ ~ 

Economic 

Biological 

Andrew Lee

Ana

and 

, Ph.D., 

l

Economic 

ysis Branch 

Economist 

Analysis Division 

~ 

503P) 

~ 

Amet Jones, Chief ~ rJ...,i) 

Biological Analysis Branch ~ 7 

Diann Sims, Chief 

Science Information and Analysis Branch~ _ 

Timothy Kiely, Chief ~ ~ Economic Analysis Branch 

Biological and Economic Analy s Division (7503P) 

TO: Steven Snyderman, Chemical Review Manager 

Risk Management and Implementation Branch 3 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel Date: April 2, 2014 

Page 1 
SUMMARY 

Pyraflufen-ethyl was first registered in the U.S. in 2002 and it is registered for the control of 

certain broadleaf weeds in many agricultural and non-agricultural use sites. Pyraflufen-ethyl is a 

contact type herbicide used as a defoliant in cotton and desiccant in potatoes to facilitate the 

harvesting of these crops. Also, pyraflufen-ethyl is used as a pre-plant burn-down, at plant before 

the crop emergence, and as a post-emergence treatment depending on the crop and stage of the 

crop growth. 

Based on private market usage data from 2003-2012, usage averaged approximately 2,000 

pounds active ingredient (a.i.) applied annually approximately on 654,000 acres. The average 

application rate over this time period was 0.003 pounds a.i. /acre. Proprietary data show about 

100 lbs. a.i. were used on turf and ornamentals in 2012. Based on the proprietary data, cotton, is 

the crop with highest usage and Texas, Georgia, California, and North Carolina were the states 

with higher usage of pyraflufen-ethyl. NASS usage data are not available for this herbicide for 

non-agricultural use sites. 

INTRODUCTION 

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

overview of the pest management roles and quantitative usage information for pyraflufen-ethyl. 

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

use and usage data for pyraflufen-ethyl to describe the role of this chemical in pest management. 

Additional information on use is available in the pyraflufen-ethyl LUIS Label Data Report. 

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

risk and benefit assessors, OPP risk managers, and the general public during the Registration 

Review process of this pesticide. 

USE SITES 

Agricultural Use Sites 

The registered agricultural use sites of pyraflufen-ethyl include: tree nuts, grapes, pome fruits, 

stone fruits, dates, figs, mangos, loquat, persimmons, pomegranates, kiwi, chicory, ginger, 

turmeric, cucurbits, fruiting vegetables, leafy vegetables, cole crops, root crops, beans, peas, 

lentils, com, barley, oats, rye, wheat, sugarcane, ginseng, flax, safflower, sunflower, canola, 

sugar beets, celery, cotton, mustard, olives, sorghum, soybeans, pastureland, conservation 

reserve program, and christmas trees. 

Non-agricultural Use Sites 

The registered non-agricultural use sites of pyraflufen-ethyl include: ornamentals, grasses, ditch 

banks, uncultivated areas, vacant lots, airfields, rights-of-way, roadsides, railroads, lumber yards, 

industrial sites, storage areas, fencerows, hedgerows, fences and commercial areas. 

Page2 
FORMULATIONS AND APPLICATION METHODS 

Pyraflufen-ethyl formulations include emulsifiable concentrate and liquid. Pyraflufen-ethyl can 

be applied using ground and aerial application equipment, but application of this product with 

any type of irrigation system is prohibited. 

HISTORY OF PYRAFLUFEN-ETHYL AND BEAD PRODUCTS 

Pyraflufen-ethyl is an herbicide registered for use in the U.S. since 2002 (USEPA, 2014). 

A Screening Level Usage Analysis (SLUA) provides percent crop treated for many crops for 

which usage data were available (BEAD, 2013). For pyraflufen-ethyl, the agricultural sites with 

the greatest number of pounds used were on cotton. In terms of the percent crop treated, 

tomatoes and cotton averaged 10 and 5 percent, respectively. 

USAGE 

Agricultural Usage 

Based on private market usage data from 2003-2012, usage averaged approximately 2,000 

pounds active ingredient (a.i.) applied annually on approximately 654,000 acres treated. The 

average application rate over this time period was 0.003 pounds a.i./acre. Figure 1 represents 

pyraflufen-ethyl usage in pounds a.i. over the 2003-2012 timeframe. Figure 2 represents total 

area treated in acres over the same timeframe (Proprietary Data, 2003-2012). 

FIGURE 1. raflufen-eth 

Total Pounds AI 

M 

0 

0 

N 

Source: Proprietary Data, 2003-2012 

..r 

0 

0 

N 

1.1) 

0 

0 

N 

OJ:) 

0 

0 

N 

Page 3 

r-. 

0 

0 

N 

Years 

00 

0 

0 

N 

0) 

0 

0 

N 

0 

rl 

0 

N 

rl 

rl 

0 

N 

N 

rl 

0 

N 
FIGURE 2. P raflufen-eth I Total Area Treated in Acres 2003-2012 

1,400,000 .,------- ------ --- ----- ~--

Total Area Trea ed 

0 +---.---.---.---.--~- .---.----. ---.-~ ('\") 

0 

0 

N 

""" 0 

0 

N 

Source: Proprietary Data, 2003-2012 

U'l 

0 

0 

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ID 

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0 

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,..... 

0 

0 

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Years 

~ 0 

N 

0'1 

0 

0 

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0 

.-4 

0 

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0 

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

Applied (2003-2007 and 2008-2012) 

2003-2007 2008-2012 

Average Annual = 1,500 lbs/yr Average Annual = 1,800 lbs/yr 

Crop %Lbs Crop %Lbs 

Cotton 91% Cotton 79% 

Fallow 3% Grapes, Wine 6% 

Wheat, Winter 2% Grapes, Raisin 3% 

Potatoes 2% Wheat, Spring 2% 

Source: Proprietary Data, 2003-2012. 

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

Applied (2003-2007 and 2008-2012) 

2003-2007 2008-2012 

Average Annual Usage= 1,500 lbs/yr Average Annual Usage =1 ,800 lbs!'yr 

State %Lbs State % Lbs 

Texas 32% Texas 35% 

Georgia 23% California 22% 

California 12% North Carolina 16% 

North Carolina 11% Georgia 14% 

Source: Proprietary Data, 2003-2012 

The major agricultural use ofpyraflufen-ethyl between both the 2003-2007 and 2008-2012 time 

frames was on cotton (91% of total pounds applied in 2003-2007, and on cotton (79% of total 

pounds applied in 2008-2012) followed by fallow (3%) and winter wheat and potatoes (2% each) · 

in 2003-2007, and wine grapes (6%), raisin grapes (3%) and spring wheat (2%) in the 2008-2012 

Page4 
time frame compared to the usage during the timeframe from 2003 to 2007. However, total 

pounds applied in cotton averages somewhat higher in the more recent time period and has been 

increasing. Use on cotton is primarily as a defoliant. 

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

(raisins and wine) at 0.005 lbs. a.i./acre and the lowest for spring wheat at 0.001 lbs. a.i./acre as 

shown in Table 3. 

Application Rates 

Table 3. Pyraflufen-ethyl Use on Top Crops: Average A.I. Rate, 2008-2012 

Crop Average Annual Average Total Acres Avg. A.I. Rate (lbs 

Pounds Treated* a.i.!acres) 

Cotton 1,403 513,391 0.003 

Wine Grapes 106 22,135 0.005 

Raisin Grapes 46 9,626 0.005 

Spring Wheat 25 28,647 0.001 

*Total Acres Treated sums all acres treated for a crop, mcludmg those acres that rece1ve multiple treatments. 

Source: Proprietary Data, 2008-2012 

Geographic Distribution of Pyraflufen-ethyl Use 

Agricultural Use Intensity ofPyraflufen-ethyl Use in the U.S. 

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

the average annual amount (in pounds) of the active ingredient applied per 1,000 acres of crop 

acres grown. This differs from the application rate, which is expressed as the pounds a.i. applied 

per treated area. Figure 3 spatially represents pyraflufen-ethyl use intensity in the United States. 

This may be due to the higher production of cotton and grapes in Texas, California, Georgia and 

North Carolina. For more information about this map, see Appendix A. 

Page 5 
FIGURE 3.Annual average agricultural use intensity of pyraflufen-ethyl (2008-2012). 

Pounds Active Ingredient 

per 1.000 Crop Acres Grown 

c::J NoData 

D <o.ooo1 

- 0.0007- 0.0023 

- 0.0024- 0.0106 

- 0.0107- 0.018 

- >0.018 

(Source: Proprietary Data) 

Non-Agricultural Usage 

Proprietary data show about 100 lbs. a.i. are used on turf and ornamental in 2011. There are no 

reported non-agricultural NASS usage data for pyraflufen-ethyl. 

BIOLOGICAL ASPECTS RELEVANT TO PYRAFLUFEN-ETHYL 

Pyraflufen-ethyl is a contact type herbicide belongs to the phenyl pyrazole group of herbicides 

(Group 14). Herbicides in this group also identified as protox or PPO inhibitors. The mechanism 

of action of the herbicides in this group is inhibition of the activity of protoporphyrinogen 

oxidase, an enzyme found in plant species. The inhibition of this enzyme in chloroplasts leads to 

subsequent cell membrane destruction and necrosis leading to the death of susceptible weeds. 

Page 6 
ROLE OF PYRAFLUFEN-ETHYL IN PEST MANAGEMENT 

Pyraflufen-ethyl is registered for the control of susceptible annual and perennial broadleaf weeds 

in many agricultural and non-agricultural use sites described under the usage section of this 

document. Major agricultural use sites include: field com, cotton, potatoes, soybeans, wheat, and 

tomatoes. The major non-agricultural use sites include: airfields, rights-of-way, roadsides, 

railroads, lumber yards, industrial sites, storage areas, fencerows, hedgerows, fences and 

commercial areas. 

Pyraflufen-ethyl can be applied as pre-plant bum-down, pre-emergence, and post-emergence 

treatments. It can be tank-mixed with other herbicides such as dicamba to broaden the spectrum 

of weed control (University of California, 2014). Redroot pigweeds (Amaranthus retrojlexus), 

common lambsquarters (Chenopodium album), kochia (Kochia scoparia), prostrate knot weeds 

(Polygonum aviculare), Russian thistle (Sa/sola spp.) are some of the key broadleafweed species 

that can be managed by applications ofpyraflufen-ethyl (University of California, 2014). 

Pyraflufen-ethyl is also, used as a plant desiccant on potato and defoliant on cotton. Applications 

of pyraflufen-ethyl on cotton increases the production of ethylene in cotton plants causing the 

leaf abscission which facilitates harvesting of cotton. Also, it reduces the amount of inert matter 

mixed with the harvested cotton. Pyraflufen-ethyl is applied on potato as a harvest-aid treatment 

(desiccant) to dry the plant before digging the soil for harvesting of potatoes. 

According to the International Survey of Herbicide Resistant Weeds (ISHR W), only a single 

weed specie (Ambrosia artemisiifolia) has developed resistance to the mechanism of action of 

pyraflufen-ethyl (Heap, Online Publication, Undated). Therefore, pyraflufen-ethyl can be used 

as a tool in resistance management programs; especially, for the management of weed species 

which have developed resistance to herbicides with different modes of action. For example, in 

South Carolina, use ofPPO-inhibitors is recommended for an excellent control of ALS 

(Acetolactate Synthase) and glyphosate-resistant Palmer amaranth biotypes (South Carolina Pest 

Management Handbook for Field Crops, 2014). 

DATA NEEDS 

The Agency currently does not have important information on pyraflufen-ethyl. Obtaining the 

following information on agricultural crops that are registered but are not surveyed, such as flax, 

and Christmas trees, and non-agricultural use sites such as ornamentals, rights-of-way, roadsides, 

railroads, lumber yards, industrial sites, storage areas, fencerows, hedgerows, fences and 

commercial areas may improve future assessments conducted by the Agency related to the use 

and importance of pyraflufen-ethyl. 

Page 7 
REFERENCES 

BEAD, 2013. Pyraflufen-ethyl Screening Level Usage Analysis. Biological and Economic 

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

April15, 2013. 

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

Publication. Available at:www. weedscience.orhttp:/ /www. weedscience.org/summary/M 

OA.aspx .. 

Accessed on Jan. 22, 2014. 

Proprietary Data. 2003-2012. 

South Carolina Pest Management Handbook for Field Crops. 2014. Available at: 

http://www .clemson.edul extension/rowcrops/pest/fi les/2 0 14 %20Pest%20management%2 

Ofiles.pdf/weedcontrolincottonPMH2014.pdf. Accessed on April18, 2014. 

University of California Pest Management Guidelines. 2014. Available at: 

http://www.ipm.ucdavis.edu/PMG/r730700411 .html. 

Accessed on March 14, 2014. 

USEPA. 2014. Federal Register. Online Publication. Available at: 

http:/ /iaspub.epa.gov/apex/pesticides/f?p=CHEMICALSEARCH:3 :0: :NO: I ,3,31, 7,12,25: 

P3 XCHEMICAL ID:3650 . Accessed on April 11,2014. 

USDA, 2006-2010. NASS Crop Reporting Districts. Available at: 

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

uestions/county list.txt. Accessed on March 14, 2014. 

USDA, 2007. Census of Agriculture. Available at: 

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

WSSA, (Weed Science 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 on, Jan. 16, 2014. 

Page 8 
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, [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 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 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 

• 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 of the land being 

managed for agricultural purposes. 

Page9 
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 10