UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

MAY 19 2011

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

MEMORANDUM

SUBJECT: BEAD Chemical Profile for Registration Review: Benfluralin (084301)

FROM: Sunil Ratnayake, Botanist ~- A' lVv1

Biological Analysis Branch \. 'V'<.J.-.. \

Sepehr Haddad, Environmental Protection Specialist / 1'-../ 1/ I

Science Information and Analysis Branch '7

Andrew Lee, Economist tJ..1. (!.

Economic Analysis Branch 1

Biological and Economic Analysis Division (7503P)

THRU: Arnet Jones, Chief

Biological Analysis Branc

Diann Sims, Chief /'(2::1--#'L-'7'..9-H'-n/l....-1.

Science Information and AnalYGJiSch

Timothy Kiely, Chief '

Economic Analysis Branch

Biological and Economic Analysis Division (7503P)

TO: Katherine S1. Clair, Chemical Review Manager

Risk Management and Implementation Branch 2

Pesticide Reevaluation Division (7508P)

Product Review Panel date: May 11,2011

INTRODUCTION

The purpose ofthis document is to convey usage information and a broad overview ofthe pest

management roles of pesticides that are beginning to undergo registration review. The

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

ofBenfluralin (084301), and eventually the general public. This document builds upon the data

already provided in the "Usage and Label Use Data Packages" that are also provided to

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Registration Review teams by BEAD. The document is based on information and data available

to BEAD as ofMay, 2011.

Benfluralin belongs to dinitroraniline class of herbicides and it is applied as a pre-emergence

treatment to control grasses and small seeded broadleafweed species. Benfluralin is used in many ,

agricultural and non-agricultural sites (USEPA, 2004). Benfluralin needs to be soil incorporated to

minimize the loss of herbicide activity due to photodecomposition and volatility (Dow Chemical Co.,

2010). Benfluralin inhibits the cell division and act as a mitotic poison. Therefore, growing points

such as roots and shoots are most affected. It is absorbed by roots and shoots of emerging weed

seedlings (Peterson et al., 2010). Benfluralin can be applied alone or tank mixed with other

compatible herbicides to increase the weed control spectrum (Dow Chemical Co., 2010).

USE SITES

Agricultural Use Sites

Benfluralin is used to control grasses and small seeded broadleafweeds in lettuce, alfalfa,

peanut, clover, birdsfoot trefoil, nonbearing fruit and nut trees, nonbearing berries, and

nonbearing vineyards.

Non-Agricultural Use Sites

Benfluralin is used to control weeds in ornamentals, rights ofway including industrial sites, utility

substations, highway guardrails, sign posts, and irrigation systems.

COMMON FORMULATIONS AND APPLICATION METHODS

It is formulated as emulsifiable concentrate, granules, soluble concentrate/liquid, water dispersible

granules and ready- to- use -solutions. Benfluralin can be applied using tractor mounted sprayers

or hand sprayers.

USAGE

Agricultural Usage

Based on private market usage data from 1998-2010, usage averaged approximately 100,000

pounds active ingredient (a.i.) for 100,000 acres treated (Proprietary Data, 1998-2010). Figure 1

presents benfluralin usage over the 1998-2010 timeframe for alfalfa, lettuce and peanuts. Minor

benfluralin usage has been reported on tobacco, while usage has also been reported on three sites

for which benfluralin is not registered; onions, broccoli, and pasture/range. The use on peanuts

was voluntarily cancelled in 2008.

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FIGURE 1.

Benfluralin Usage (1998-2010)

250,000 I

I

o

• Peanuts

• lettuce

• Alfalfa

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Years

Source: Proprietary Data, 1998-2010

Between 2008-2010, the states with the most agricultural usage in terms of pounds a.i. applied

were Arizona (60%), California (19%) and Alabama (19%). Other states (2%) where use has

been reported between 2008-2010 are Georgia and Tennessee (Figure 2).

USE TRENDS

As shown in Figure 1, between 1998 and 2010, benfluralin use reached a peak in 1999 and the

lowest use was reported in 2009. An increase in use occurred during 2008 but use was cancelled

in September ofthat year, and therefore no usage is shown for peanuts in 2009 and 201D, the

most recent years for which we have data. Use on alfalfa was the highest in 1999 and steadily

decreased until 2004. Usage on alfalfa increased from 2006 through 2008 and there was no use

reported in 2009. The use ofbenfluralin on lettuce has remained fairly constant from 1998

through 2008, with the least use on lettuce reported in 2009.

Figure 2 presents the states with the highest pounds a.i. used from 1998-2000, as compared to the

states with the highest pounds a.i. used from 2008-2010. As shown in Figure 2, the proportion of

use in California has decreased by approximately 50% within the last decade, while use in

Alabama has increased during the same period to approximately 20% oftotal pounds a.i. applied.

A review of proprietary data indicates that this is due to a decrease in use on alfalfa in California

and the increase in use on peanuts grown in Alabama in 2008 before the use on peanuts was

voluntarily cancelled. The last pie chart in Figure 2 shows the states with the highest use in

2009-2010 after the use on peanuts was cancelled.

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FIGURE 2. Comparison of States with Highest Use Between 1998-2000 and 2008-2010

Timeframes & States with Hi hest Use in 2009-2010 After Cancellation of Peanut Use

States with Highest Use - Percent of Total Lbs.

Applied

1998-2000

States with Highest Use - Percent of Total Lbs.

Applied

2008·2010

OTHER

2%

States With Highest Use - Percent of Total Lbs.

Applied

2009-2010

(after cancellation of use on peanuts in 2008)

Source: Proprietary Data, 1998-2010

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Non-Agricultural Usage

In terms of non-agricultural usage, data are available for usage by consumers for lawn use and

for lawn care operators (LCO's) and for uses such as golf courses, landscape,

nursery/greenhouse, and turf farms. Generally, over the reported years (1999 through 2006), the

majority of use was by consumers, LCO's and golf courses.

Consumers used 1.8 million pounds a.i. in 2000; 800,000 pounds a.i. in 2003, and 800,000

pounds a.i. in 2005.

LCO's used approximately 171,000 pounds a.i. in 1999. Use decreased to approximately 85,000

pounds a.i. in 2002; 99,000 pounds a.i. in 2004; and 35,000 pounds a.i. in 2006.

Benfluralin use on golf courses declined from 1999 through 2006, with approximately 45,000

pounds a.i. used in 1999; 16,000 pounds a.i. in 2002; 8500 pounds a.i. in 2004; and less than 300

pounds a.i. in 2006.

Finally, for Nursery/Greenhouses, the amount reported used has fluctuated from 21,000 pounds

a.i. in 1999 to approximately 200 pounds a.i. in 2002; less than 100 pounds a.i. in 2004; and

increased to approximately 2500 pounds a.i. in 2006 (Kline and Co., Inc. 1999-2006).

BIOLOGICAL ASPECTS RELEVANT TO BENFLURALIN

Inhibition of cell division is the mode of action ofthis herbicide. Therefore, it affects the growing

areas ofthe weeds such as roots and shoots (Peterson et al., 2010). Dinitroraniline herbicides have

been used more than 25 years and several weed species have developed resistance to the mode of

action ofthis class of herbicides (Heap, 1997). Biotypes of palmer amaranth (Amaranthus palmeri),

wild oat (Avenafatua), goosegrass (Eleucine indica), annual bluegrass (Poa annua), green foxtail

(Setaria viridis),andjohnsongrass (Sorghum halepense) have developed resistance to

dinitroraniline class of herbicides (International Survey of Herbicide Resistant Weeds, 2011).

Goosegrass (Eleucine indica) is the most widespread resistant weed specie for the dinitroraniline

group of herbicides. Infestations ofdinitroraniline resistant goose grass were reported in cotton

fields ofNorth and South Carolina, Alabama, Georgia, and Tennessee (Heap, 1999).

HISTORY OF BEAD ASSESSMENTS FOR BENFLURALIN

The only BEAD analysis regarding benfluralin is the alternatives assessment (Phillips, Zinn, and

Faulkner, 2004) in support ofRe-registration Eligibility Decision (RED). According to this

assessment, alternatives used for benfluralin on turf use were trifluralin, dithiopyr, prodiamine,

oxadiazone, oryzalin, and alternatives used on alfalfa were metribuzin, norflurazone, paraquat,

pendimethalin, terbacil, and trifluralin. Also, alternatives used on lettuce were bensulide,

propyzamide, benefin, and trifluralin. Although the use on peanuts was cancelled in 2008 no

BEAD analysis was conducted related to this cancellation.

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DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON BENFLURALIN

BEAD specific Registration Review issues, as relevant, including BEAD data gaps needed for

future assessments and BEAD work plan. None at this time.

REFERENCES

EPA R.E.D. Facts. Benfluralin. 2004. United States Environmental Protection Agency.

http://www.epa.gov/oppsrrd llREDs/factsheetslbenfluralin fs.pdf

Proprietary Data, 1998-2010.

Heap, I. M. 1999. Occurrence ofHerbicide Resistant Weeds, Worldwide.

http://www.weedscience.comlpaper/resist97.htm

International Survey of Herbicide Resistant Weeds. 2011. http://www.weedscience.org/In.asp

Peterson, D. E., C. R. Thompson, D. E. Shoup, and B. L. Olson. 2010. Herbicide Mode of

Action. Publication off Kansas State University Agricultural Experiment Station and

Cooperative Extension Service. http://www.ksre.ksu.edullibrary/crpsI2/c715.pdf

Phillips, W II, N. Zinn, and J. Faulkner. 2004. Potential benfluralin alternatives. Memorandum

submitted to Special Review Re-registration Division. July 15,2004.

Product Safety Assessment. Benfluralin. 2010. Publication of Dow Chemical Company.

http://www.dow.comlproductsafety/pdfs/233-00785.pdf

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