UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

APR J 3 2013 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

BEAD Chemical Profile (BCP) for Registration Review: Clodinafop-propargyl 

(125203) 

Bill Phillips, Ph.D., Agronomist~ Biological Analysis Branch ~ 

Jihad Alsadek, Ph.D., Economist .;r~ ~ /If~ Science Information and Analysis Branch 

Stephen Smearman, Economist ./._ -1 _. _ 1 

Economic 

Biological 

Analysis 

and Economic 

Branch 

Analysis 

;IJG!f-'I.VVI 

Division (7503P) 

~ 

Arnet Jones, Chief 

Biological Analysis Bran<(b 

/) 

Diann Sims, Chief /.-.!J(_£1...,.,_~~'1V'""'-" Science Information and Analysis Branch 

Economic 

Timothy Kiely, 

Analysis 

Chief 

Branch U 

~ !.) lA 

VV'-._, 

~ 

Biological and Economic Analysis Division (750 

TO: Wihelmena Livingston, Chemical Review Manager 

Risk Management and Implementation Branch 4 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel date: August 01, 2012 

Revised: March 26, 2013 

Introduction 

The purpose of this document is to convey usage information and a broad overview of the pest 

management roles of clodinafop-propargyl that is beginning to undergo registration review. The 

anticipated audience consists of the team of EPA staff currently evaluating the registration status 

1 
of clodinafop-propargyl, and e.ventually the general public. This document builds upon the data 

already provided in the "usage and 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 26, 2013. 

Herbicide Discussion 

Clodinafop-propargyl is a systemic, postemergence herbicide formulated as an emulsifiable 

concentrate and used for selected grass control in spring and durum wheat. When mixed with the 

chemical safener cloquintocet-mexyl this herbicide can be tolerated by wheat and still provides 

effective weed control. This herbicide is in the Weed Science Society group 1 and has a 

mechanism of action of inhibiting fatty acid synthesis by the inhibition of the enzyme acetylCoA carboxylase (ACCase ). 

This herbicide controls some economically key weed species that impact crop production, 

specific weed species are, green foxtail (Setaria viridis), yellow foxtail (Setaria glauca), and 

giant foxtail (Setaria faberi) as well as barnyardgrass (Echinochloa crus-galli). Currently there 

are 2 weed biotypes that are re.sistant to this herbicide, wild oats (Avenafatus) and Italian 

ryegrass (Lolium multiflorum). In addition to their resistance to clodinafop-propargyl these 

biotypes are also resistant to other Group 1 herbicides. Careful stewardship of this herbicide and 

other Group 1 herbicides are needed in order to reduce the selection of other resistant biotypes 

and to maintain this herbicide chemistry. 

Clodinafop-propargyl is primarily used in the northern wheat production areas of the country, 

concentrated mostly in the states of Idaho, Montana and North Dakota. The types of wheat 

produced in these states are durum wheat, hard red spring and winter wheat, and soft white 

spring and winter wheat. Seventy percent of the durum wheat was planted in North Dakota with 

a smaller amount in Montana (20%). 1 In 2010 and 2011, the average number of acres of durum 

wheat harvested by farmers in the states of Montana and North Dakota totaled 89% of the 

nation's durum wheat grain harvest. 

From 2006-2012, 90% of the totallbs a.i. of clodinafop-propargyl was applied to 93% of the 

total acres treated (TAT) for the various types of spring wheat; while 9% ofthe lbs a.i. had been 

applied to 7% ofthe different types of winter wheat? From 2006-2010, the annual total 

agricultural usage averaged approximately 74,000 pounds active ingredient (lbs a.i.) on 1.8 

million treated acres (approximately 3.75% of the total US harvested wheat acreage) with an 

average application rate of0.04lbs. a.i. acre. 

On average, for the years from 2006 to 2010, Montana and North Dakota farmers together 

accounted for 83% of the total.lbs a.i. of Clodinafop-propargyl used on 90% of the durum crop 

produced in the nation. This niche market for this herbicide is very important in spite of the 

relatively low total national use of74,000 pounds active ingredient. 

1 USDA, National Agricultural Statistics Service. July 2011. 

http://www .usda.mannlib.comell.edu/usda/nass/CropProd-07-12-20 11.pdf 2 EPA Proprietary Data, 2006-2010 · 

2 
The climate in the two states, Montana and North Dakota, where clodinafop-propargyl herbicide 

is currently being used the most is characterized by very cold winters with an average annual 

rainfall of go inches3 and an average soil organic matter of less than or equal to three percent4

• 

Given the soil organic matter in the states and the short soil half-life (<3 days), as well as the 

relatively high Koc (1,500-2,000) of this herbicide5

, carryover to rotated crops may not be an 

issue. 

Use Trend Summary 

Overall, the crops with most total area treated (TAT) are spring wheat (90% ), winter wheat (9% ), 

and barley and fallow (<1 %). However, the use of clodinafop-propargyl has declined since its 

peak in 2005, when use is averaged over all reported crops. Figure 1 presents the trend of use for 

clodinafop-propargyl in terms oftotal pounds. 

Figure 1. Total Annual Agricultural Usage for Clodinafop-propargyl, 2000-2010 

180,000 

0 

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 

Years 

Source: Proprietary Data, 2000 -2010 

Figure 2 provides usage data for 2006-2010. During this period, the use of clodinafop-propargyl 

on spring wheat increased in 2008 and had a slight decrease in 2009. The use on winter wheat 

was also fairly steady except.for a decrease in 2007 and 2010. There could be many factors that 

played into these use fluctuations, however there does not seem to be a single verifiable reason. 

Figure 2. Agricultural Usage :pata for Clodinafop-propargyl averaged over 2006-2010. 

3 http://www.nass.usda.gov/Charts _and_ Maps/Crops_ County/index.asp#cr 4 Flaherty, C. "What is a pound of nitrogen worth in spring wheat. MSU Communications Services, Bozeman, MT 

59717 http://www .montana.edu/cpalnews/wwwpb-archives/aglwhe _ fert.html 

5 Vencill, W.K. ed. Herbicide Handbook, Eighth Edition. 2002. Weed Science Society of America. Lawrence, KS 

66044. USA 

3 
100,000 ,---------------------

..: 

< 

"C "' c 

:s 

0 

D. 

0 

2006 2007 2008 

Years 

Source: Proprietary Data, 2006-2010 

History of BEAD assessments 

- Wheat, Spring 

- Wheat, Winter 

2009 2010 

BEAD conducted an assessment for clodinfop-propargyl for EPA's Registration Division in 

2010. A document entitled "Requested Information on Four Herbicides Used for Weed Control 

in Wheat Production" was a review by the Biological and Economic Analysis Division (BEAD) 

to provide information on four herbicides (flucarbazone-sodium, pinoxaden, clodinafoppropargyl, and pyroxsulam) used for weed control in wheat production. This information was 

needed for RD to resolve a risk issue involved with safener used in these herbicide formulations. 

To support the process, BEAD reviewed publicly available information related to application 

rates, application timing, mechanism of action and major weeds controlled by these herbicides. 

BEAD concluded that all four of these herbicides would not be applied to the same wheat field in 

the same production season. BEAD did conclude that on very rare occasions, sequential 

application of2-3 of these herbicides is possible depending on the weed spectrum and intensity 

of weed pressure found in an individual wheat field in a particular growing season. 

Conclusion 

Overall the use of clodinafop-propargyl in Idaho, Montana, and North Dakota is important for 

the control of annual and perennial grasses. As discussed earlier in this document, because of the 

magnitude of the use in Montana and North Dakota where 89% of the harvested durum wheat 

produced in the US accounted for 83% of the clodinafop-propargyl use, it is clear that there is an 

important niche use for this herbicide. 

4 
References 

Proprietary Data, 2000-2010 

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

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

USDA, 2007. Census of Agriculture. Online: http://www.agcensus.usda.gov/Publications/2007/index.asp. 

USDA, 2012. National Agricultural Statistics Service, Crop Production, Agricultural Prices, and unpublished data; 

and USDA, World Agricultural Oqtlook Board, World Agricultural Supply and Demand Estimates. Online: 

http://www .ers.usda.gov/data-products/wheat-data.aspx. 

5 
APPENDIX 

Clodinafop-propargyl Usage by Crop Reporting District (2006- 2010) 

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

expressed as the pounds a.i. applied per 1,000 acres of land in farms. This differs from 

the application rate, which is e.xpressed as the pounds a.i. applied per treated acre. 

Figure 3 spatially represents the use intensity of clodinafop-propargyl on wheat in the 

Dakotas. 

Clodinafop-proporgyl Use (2006-2010) . 

by Crop Reporting District Average 

Pounds per 1,000 Acn:s of Farmland 

- <011 

. 0.11 · 025 

c::::J o.26-o.so 

0.51 - 2.00 

- 201 - 2.50 

This is a map of agricultural P<lSticide 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 

(USDA, 2010). Pesticide usage is displayed as average pounds (for the years 2006-2010) per 1,000 acres of 

farmland 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 CREP 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 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 

6 
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 

non-Native Ameri~ans 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 (2007 Census of 

Agriculture, USOA). 

Usage is based on private market surveys of pesticide use in agriculture (Proprietary Data, 2006-2010). 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 CRJ?. 

This map displays ratio data (i..e., average pounds per 1,000 acres of farmland) summarized at a very high-level. 

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. 2006-2010 

USDA, 2006-2010. NASS Crop Reporting Districts. 

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

USDA, 2007. Census of Agriculture. 

http://www .agcensus. usda. gov /Pub lications/2007 /index. asp. 

7