UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

DEC 01 2011 

MEMORANDUM 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: BEAD Chemical Profile for Registration Review: Trifluralin (036101) 

FROM: Bill Phillips, II, PhD, Agronomist .-dJId~ Biological Analysis Branch <I3{tT . ~ 

Jihad Alsadek, PhD, Economist ~ If:- - J1 

Science Information and Analysis Branch 

Andrew 

Economic 

Lee, 

Analysis 

PhD, Economist 

Branch V'" /l~ C ~ Biological and Economic Analysis Divisi (7503P) 

THRU: Arnet Jones, Chief ~ 1'21~ Biological Analysis Branch ~"'j 

Diann Sims, Chief Lla..., ......... .e...~,.,-.L-' Science Information and Analysis Branch 

Timothy Kiely, Chief 

Economic 

Biological 

Analysis 

and Economic 

Branch 

Analysis 

<11-

Division 

ltv\. ~ (7503P) 

TO: Kelly Ballard, Chemical Review Manager 

Risk Management and Implementation Branch 1 

Pesticide Re-evaluation Division (7508P) 

Product Review Panel date: October 12, 2011 

INTRODUCTION 

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

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

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

oftrifluralin, and eventually the general public. This document.builds upon the data already 

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

Review teams by BEAD. The document is based on infonnation and data available to BEAD as 

of September 2011. 

Trifluralin is applied as a pre-plant incorporated and preemergence herbicide used to control 

small-seeded broadleafweeds and some grasses in agronomic, horticultural (ornamental and 

vegetable), and industrial sites. In addition, applications can b~ made through chemigation. 

The herbicide trifluralin is a dinitroaniline (DNA) with the mechanism of action of inhibiting the 

microtubule protein tubulin which results in the disruption of cellular mitosis. Weed control is 

achieved through root uptake of emerging seedlings. This chemical is classified as a group 3 

herbicide by the Weed Science Society of America. 

USE SITES 

Agricultural Uses 

Small fruits, Grapes, Strawberries, Citrus fruits, Nut crops, Pome Fruits, Stone Fruits, Tropical 

and Sub-tropical fruits, Beverage crops, Flavoring and Spice crops, Fruiting vegetables, Leafy 

and Stem vegetables, Root crop vegetables, Seed and Pod vegetables, Asparagus, Onions 

(Green), Fiber crops, Forage grasses, Forage legumes and other non-grass forage crops, Grain 

crops, Sugar crops, Cotton, Crops grown for oil, Soybean, Forest Trees, and Uncultivated 

Agricultural Areas. 

NOli-agricultural Uses 

Ornamental lawns and turf, Golf course turf, Ornamental herbaceous and woody, Around 

agricultural structures, Uncultivated Non-Agricultural Areas, Commercial, Industrial and 

Institutional areas, Rights-of-ways, Pre-paved areas, fencerows, Septic areas. 

There is a combination of more than 1,000 agricultural and no~-agricultural use sites registered 

for this herbicide. Overall, the agricultural uses of trifluralin are wide ranging and account for 

the majority of the herbicide applied in the U.S. 

Approximately 98% of the use sites include agronomic and horticultural crops (field and 

container), as well as turffanns. Based on total acreage treated and the total amount applied the 

primary use of trifluralin is in cotton and soybean production (Figures 1 & 2). 

The non-agricultural use sites labeled for trifluralin include conservation reserve areas, fence 

rows, golf courses, industrial areas, landfills, landscape plantings, residential areas, rights-ofway, turf (lawn care and institutional), and other less common areas such as pathways, pre-paved 

areas, septic drain fields, sidewalks, tennis courts and underground cables. 

COMMON FORMULATIONS AND APPLICATION METHODS 

Trifluralin is fonnulated as wettable powder, impregnated materials, water dispersible granules, 

and soluble and emulsifiable concentrate. . 

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Application methods for this herbicide include aerial and ground application (banded, broadcast 

and spot spray, broadcast and hand-held granular, soil incorporated, and chemigation). ' 

USAGE 

Agricultural Use and Usage Data 

Based on private market pesticide usage data from 2006-2010, the annual total agricultural usage 

averaged approximately six million pounds active ingredient for seven million treated acres for 

an overall application rate of less than 1 lb. a.i. per acre. 

From 2006-2010, the crops with the most use in terms of total pounds of active ingredient 

applied are cotton (53%), soybeans (25%), and alfalfa (5%). The crops with most total area 

treated (TAT) are cotton (54%), soybeans (24%), dry beans (4%), and tomatoes (4%). 

On average, the states with the most agricultural usage in terms of pounds a.i. applied are 

Texas (45%), Iowa (11%), California (9%), Georgia (6%), and Minnesota (4%). 

(Proprietary Data, 2006-2010). 

Agricultural Use Trends 

Figure 1 provides usage trends as pounds applied for the largest agricultural markets for 

trifluralin. The use oftrifluralin on alfalfa, cotton, soybeans, sunflowers and other crops declined 

during the period 1998-2010. 

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Fi e 1. Trifluralin A 1998-2010 

12,000,000 

o 

1998199920002001200220032004200520062007200820092010 

Years 

"-Alfalfa 

___ Cotton 

-'-Soybeans 

Sunflowers 

_ Other 

Other crops include dry beans/peas (3% each), spring wheat and tomatoes (2% each), and sugarcane, 

canola, fallow, and green beans (1 % each). 

Source: Proprietary Data, 1998-2010 

Figure 2 provides usage data for 2006-2010. The use oftrifluralin on alfalfa declined during 

this time period. Use on cotton and soybeans fluctuated, declining between 2006 and 2008 and 

increasing between 2009 and 2010. The use on other crops w~ relatively stable. 

Fi e 2. Trifluralin A 

4,000,000 

:i 

III "-Alfalfa '0 

c 

~* ___ Cotton ;:, 

~ 

0 .. 

* • -.-Soybeans )E H H )( )( Other 

0 

2006 2007 2008 2009 2010 

Years 

Other crops include dry beans/peas and tomatoes (3% each), sunflowers and sugarcane (2% each), and 

fallow and green beans (1 % each). 

Source: Proprietary Data, 2006-2010 

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Non-Agricultural Use and Usage Data 

The use oftrifluralin on golf courses declined from 31,000 lbs. a.i. in 2002 to 4,000 lbs. a.i. in 

2006. The use of trifluralin by landscape contractors declined between 2002 and 2006 from 

50,000 lbs. a.i. in 2002 to 24,000 lbs. a.i. in 2006. The use of this chemical by lawn care 

operators (LCOs) fluctuated between 2002 and 2006. The use of trifluralin in institutional turf 

facilities rose from 32,000 lbs. a.i. in 2002 to 401,000 lbs. a.i. in 2006. The use oftrifluralin rose 

also on turf management and horticultural nurseries from 311,000 lbs. a.i. in 2002 to 532,000 lbs. 

a.i. in 2006. 

Because there are a limited number of preemergent herbicides available for use by homeowners 

and professionals alike, formulations oftrifluralin for use in landscape and lawn sites have high 

benefits. Trifluralin can be formulated as a granular as well as a fertilizer impregnated form 

making it very simple for homeowners and landscapers to apply to lawns and to incorporate 

and/or cover beneath mulch in landscape beds. 

Consumers used about 400,000 pounds of trifluralin in 2003 and just under one million pounds. 

in 2005 (most recent data available to EPA). In 2003 the use oftrifluralin by retail consumers, 

based on lbs. a.i., was as an herbicide/fertilizer mix, while in 2005 the primary uses of trifluralin 

was divided equally between garden and lawn care fertilizer mix applications. More than 

400,000 lbs. a.i. was applied in 2005 while use as a fertilizer mix was 500,000 lbs. a.i. Of the 

DNA herbicides that overlap in these use sites, pendimethalin was the primary herbicide for lawn 

care use (>3.0 million lbs. a.i.), while benefin (800,000 lbs. a.i.) use was only slightly higher than 

trfl~alin (500,000 lbs. a.i.). However, neither pendimethalin nor benefin were ranked within the 

top 98% of the herbicides used for garden weed control. While trifluralin is not the only 

preemergence herbicide labeled for garden use, the use sites ar€? numerous (flowerbeds, 

vegetable, under trees and shrubs) and the pest spectrum for these uses is at the same time broad. 

The total amount oftrifluralin active ingredient (a.i.) applied by consumers are nowhere near the 

level of the agricultural uses; however, the benefits are nonetheless significant and thus are not 

well represented by the totallbs. a.i. reported. . 

T a e bl 1 T' nur fl al' 10 N on-A' .gncu ltural U se 

2002 2003 2004 2005 2006 

Segment/Site (lbs. a.i.) (lbs. a.i.) (lbs. a.i.) (lbs. a.i.) (lbs. a.i.) 

Golf Courses 31,000 - 23,000 - 4,000 

Landscape Contractors 50,000 - 46,000 - 24,000 

Lawn Care Operators (LCOs) 127,000 - 171,000 - 65,000 

Institutional Turf Facilities 32,000 - 43,000 - 401,000 

Turf Management & 311,000 - 306,000 - 532,000 

Horticultural Nurseries 

Consumers - 400,000· - 970000·· , - - = Data are not available for the use within the year . • Lawn as a fertilizer mix product. 

•• 470,000 lbs. a.i. in garden (flowerbeds, vegetable, under trees and shrubs) & 500,000 lbs. a.i. in lawn as a 

fertilizer mix product. 

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Source: 

Kline and Company, Inc., 2002-2006 

BIOLOGICAL ASPECTS RELEVANT TO TRIFLURALIN 

Only goosegrass (Eleusine indica) has been confirmed as resistant to trifluralin in the U.S. This 

weed species is not a noxious weed, however it may be important with respect to crop yield loss 

in regional areas. ' 

Because trifluralin is highly lipophilic it is quickly taken up by plants. It is also this lipophilicity 

that limits its movement through plants by binding with cell structures such as membranes. It is 

for this reason that this herbicide only controls germinating seedlings by causing roots to stop 

growing before they are able to begin to support plant growth. The advantage of controlling 

weed species at this stage of growth eliminates the chances of weeds competing for resources 

prior to their control as well as their producing seed. 

HISTORY OF BEAD ASSESSMENTS FOR TRIFLURALIN 

In 2009, BEAD prepared a usage report which included trifluralin as one of the chemicals being 

evaluated in support of a red legged frog endangered species assessment for California (Carter 

and Kaul, 2009). This information may be useful in the reexamination of risk-benefit balance 

for trifluralin, which is the purpose of registration review process. 

DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON TRIFLURALIN 

Obtaining additional information on the following items would improve future BEAD 

assessments of the importance of Trifluralin and may be required as part of the registration 

review of this pesticide. 

Information is needed in the following areas regarding specific uses where trifluralin may have 

significant benefits: 1. Golf courses, 2. Landscape contractors, 3. Lawn care operators, 4. 

Institutional turf facilities, 5. Turf management companies, 6. Horticultural nurseries, and 7. 

homeowner uses. 

REFERENCES: 

Proprietary Data, 1998-2010 

Kline and Company, Inc., 2002-2006 

Carter, J. and M. Kaul. 2009. County-Level Usage for Strychnidin; Strychnine; Tric1opyr, 

butoxyethyl ester; Tric1opyr, triethylamine salt; Diflubenzuron; Trifluralin ; Thiobencarb; 

Chlorpyrifos; Vinclozolin; Iprodione in California in Support of a Red Legged Frog Endangered 

Species Assessment. June 8, 2009. . 

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