UNITED STATES ENVIRC'NMENTAL PROTECTION AGENCY

WASHIN3TON, D.C. 20460

MAil 30 2011

OFFICE OF CHEMICAL SAFETY

AND POLLUTIO N PREVE NTION

MEM ORANDUM

SUBJECT: BEAD Chemical Profile for Registration Review: Tribenuron-methyl

(PC Code: 128887)

FROM : Jihad Alsadek, Economist ~~

Science Information and An::ty;is n;;-nch

Bill Philli ps, II, Ph.D., Agronomist

Biological Analysis Branch

Biological and Economic Anal ivision (7503P)

Diann Sims, Chief M'"::~ Science Information and Analysis Branch

Timothy Kie ly, Chief -.g z.e,l\

Economic Analysis Branch I .p,.. --rBiological and Economic Analysis Division (7S03P)

Amet Jones, Chief

Biological Analysis Branch-' U

Monica Wait, Chemical Review Manager

Pesticide Re-evaluation Division (7508P)

John Faulkner, Economist

Economic Analysis Branch

TO:

T HRU

Peer Review Panel Date : September 22, 2010

INTRODUCTION

The purpose of this 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 ofEPA staff currently evaluating the registration status

of tribenuron-methyl, 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

Registration Review teams by BEAD.

Tribenuron-mcthyl is an herbicide used in small grain crops, corn, cotton, rice, sorghum,

soybeans, and some horticultural crops to control annual broadleafweeds and the suppression of

some perennial weed species. Additional uses include weed control in tobacco and pasture sites.

Weeds controlled include many species and biotypes that are resistant to several classes of

herbicides. Tribenuron-methyl is a sulfonylurea with the mode of action of inhibiting the

enzyme acetolactate synthase, and is classified by the Herbicide Resistance Action Committee

and Weed Science Society of America in group BI2I

. Currently, there are several weed species

and biotypes reported as resistant to this family of her oicides in the U.S.

USE SITES

Agricultural Use Sites

Use sites for tribenurcn-methyl are, Alfalfa, Corn - pop, Potato - white/irish, Barley, Corn -

sweet, Pumpkin, Beans - dried-type, Cotton (unspecified), Rice, Beans - succulent (snap),

Cucumber, Sorghum, Blueberry, Fallowland / cons. Reserve, Sorghum (unspecified),

Cabbage, Flax, Soybeans (unspecified), Canolauapc, Lentils, Sugar beet, Carrot (including

tops), Melons - water, Sunflower, Cereal grains, Mustard, Sweet potato, Clover, Oats,

Tobacco, Corn (silage), Onion, Tomato, Corn (unspecified), Pasture, Triticale, Com - field,

Peanuts (unspecified), Wheat, Peas (unspecified), Yam

Non-Agricultural Use Sites

None

COMMON FORMULATIONS AND APPLICATION METHODS

Tribenuron-methyl is formulated as water dispersible granules (dry flowable) only. Tribenuronmethyl is applied as a Spot treatment, broadcast or bu-ndown treatment via ground or with

aircraft. It can also be applied as a Band treatment with a band sprayer and ground; and as a low

volume spray via ground or aircraft.

Tribenuron-methyl usage data on post-harvest and non-agocrops/sites are not available from our

current data sources.

USAGE

Agricultural Usage

1 Herbicide Resistant Action Committee

http://www.weedscience.org/summary/Chemj-amilySum.asp?IstActive- 146&blnSubI=0 0&IstHRAC=

2
Based on private market pesticide usage data, the annual total agricultural usage averaged

approximately 54,000 pounds active ingredient (AJ.) for almost 9 million acres from 1998-2008

(GfK Kynetec, 1998-2008). The use oftri henuron-m ethyl, in pounds A I., and acres treated are

relatively stable over the period span.

From 1998-2008, the largest markets in tenu s of total pound s of active ingredient applied are:

winter wheat (46%), spring wheat (34%), barley (11%), and soybeans (6%). The highest acreage

crops treated: winter wheat (45%), spring wheat (38%), barley ( 10%), and soybeans (5%) (GfK

Kynetec, 1998-2008).

The states with the most agricultural usage in tenus of Pounds AI applied are:

North Carolina (27%), Montana (8%), Idaho/Washingtonllllinois/Kentucky (6% each). The

states with the most total area treated (TAT) are: North Carolina (28%), Montana (9%),

Washington (8%), and Idaho/South Dakota (6% each) (GfK Kynetec, 1998-2008).

Non-Agricultural Usage

Tribenuron-methyl usage data on non-agricultural usage are not available from our current data

sources.

USE TRENDS

The following graphs provide usage trends, in terms of pounds applied, for tribenuron methyl' s

largest agricultural markets. The data provided in this section are provided for preliminary

scoping purposes only because the data have not been analyzed. Use of tribenuron-methyl on

winter wheat is relatively stable over the time span 1998-2008, except for the year 2003 when

usage was the highest. Usage on spring wheat and barley were on the decline during the same

time period. Usage on soybeans started to rise in 2001 and reached a maximum in 2008.

Winter Wh.,.t

35,000

I

;;:

-e

•

I c

,

0

.. 0

1998 t999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Yuar

3
Spring Wheal

35,000

:;;:

-e

•

C

,

0

c,

0

1998 1999 2000 2001 2002 2003 2004 :W05 2006 2007 2008

Year

Barley

12,000

:;;:

."

•

C

,

0

c,

0 l JU]j]J

1998 1999 2000 2001 2002 2003 2004 ;W05 2006 2007 2008

Year

Soybeans

25,000

:;;:

-e

•

C

,

0

a,

0 n n n

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

4
BIOLOGICAL ASPECTS RE LEVANT TO TRIBENURON -METHYL

Currently, there are several weed spec ies an d biotypes reported as resistant to this family of

herbicides in the U.S.

IIISTORY OF BEAD ASSESSMENTS FOR TRIBENURON-METHYL

In an alternative analysis (Zinn and Kim, 2005), tribenuron methyl was identified as a likely

alternative to chlorsulfuron. In an assessment of potential mitigation measures for atrazine

(Jones and Widawsky, 2003) the only recommended alternative is thifensulfuron-methyl plus

tribenuron-methyl for winter weed control on sorghum. No other assessments or Section 18

reviews were found in the BEAD database,

DATA NEEDS RE LEVANT TO BEAD'S FUTURE WORK ON TRIBENURONMETHYL

Data regarding the decli ne in use in spring wheat.

Data regarding the rapid adoption of this herbicide in soybean.

REFERENCES

GtK Kynetec, 1998-2008. Proprietary Data.

Jones, Arnet W. and Widawsky, David. 2003. Assessment of Potential Mitigation Measures for

Atrazine, 13 Feb 2003.

Kline & Company, Pro fessional Turf and Ornamental Marke ts for Pesticides and Fertili zers

(2000, 2002, 2005, and 2007)

Kline & Company, Consumers Markets for Pesticides and Fertilizers (200 1, 2004, and 2006)

FIFRA Section 18 Eme rgency Exemptions Database ,

http://cfpub1.epa·90v/oppref/section18/search.c'm

Zinn, Nicole and Kim, Jin. 2005. Addendum to Chlorsulfuron Benefits Discussion for Aerial

Applications: Alternatives Analysis for Winter Wheat; D3 13380, 5 May 2005 .

5