UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

DEC 0 3 2010

OFFICE OF CHEMICAL SAFETY "OJ" Dn., I rr",......,t\n:;.."........

MEMORANDUM

SUBJECT:

FROM:

THRU:

TO:

BEAD Chemical Profile for Registration Review : Terbacil (01270 1)

Sunil Ratnayake, Biologist .• . 0

Biological Analysis Braoch IW""" \

Sepehr Haddad, Environmental Protection Speeialist Ir J J J

Science Information and Analysis Branch fH;'-

Elizabeth Hill, Economist ~~ I J

Economic Analysis Branch ~L.~""\:--((:l.,'----J,\ t,.lo \

Biological and Economic Analysis Division (7503 P)

Amet Jones, Chief '/) ues-«

Biological Analysis Branch

Diann Sims, Chief j{];,0'-""-.,~"1""'/ Science Information and Analysis Branch

Timothy Kiely, Chief ' AI I A

Economic Analysis Branch v"f\..V r\

Biologica l and Economic Analysis ivision (75OJJ)

James Parker, Chemical Review Manager

Pesticide Reevaluation Division (7508?)

Peer Review Panel date: 0812512010

INTRODUCTION

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

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

antici pated aud ience consists of the team of EPA stafT currently evaluating the registration status

of Terbacil, and eventually the general pub lic. 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.

Terbacil is a selective herbicide used to control broadleaf weeds on terrestrial food/feed crops.
Terbacil is formulated as water dispersible granules and wettab le powder. These products can be

applied by aircraft or gro und equipment including boom sprayers. Use practice limitations

include prohibition of ap plications through any type of irrigation system. Grazing or feeding

forage or hay from treated areas to livestock is also prohibited (EPA. 1998). It is sprayed on soil

surfaces pre ferably just before or during the period of active weed growth. Terbacil is absorbed

by root s and kills weeds by inhibiting photosynthesis at photosystem II. It is a member of the

substituted uracil chemical family (Extoxnet, 1996).

USE SITES

Major use sites ofterbacil under the terrestrial food category are appl es, mint, sugarcan e,

asparagus, blackberry, boysenberry, dewberry, loganberry. peach. raspberry, youngberry, and

strawberry.

Alfalfa is the major use site ofterbacil under the terrestrial feed category. In addition. terbacil is

used for weed control in forestry (e.g, cottonwood).

COMMON FORMULATIONS AND APPLICAnON METHODS

This chemical is formu lated as water dispersible granules and wettab le powder. Terbac il may be

applied by direct spray with a boom sprayer, as soil band treatment or as soil broadcast treatment

using a boom sprayer or by aeri al application.

USAGE

Agricultural Usage

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

approximately 64,000 pounds active ingredient (A.I.) for 86,000 acres from 1998 to 2008 (GtK

Kynetec, 1998 M 2008). The use of terbacil steadily decreased from its peak in 1998 through 2002

and then once again from a high in 2003 through the lowest level in the past 11 years in 2008

(See Figures 1 and 2).

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Figure 1.Terbacil Usage, Pounds Applied, 1998-2008

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

Figure 2. Terbacil Acres Treated, 1998-2008

160,000

u ~~

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

3
From 1998-2008, the largest markets in terms oftotal pounds of active ingredient appli ed and

acres treated was for app les (32%), alfalfa (31%), peache s (18%), and sugarcane (16%). See

Figure 3.

Figure 3. Poun ds AI Applied By Crop, 1998-2008

3%

18%

31 %

E! Apples

• Alfalfa

o Peaches

o Sugarcane

• Other

The states with the most agricultural usage in terms of pounds A I. applied are: Oklahoma (23%),

Washington (18%) and Louisiana (17%), followed by New York, Michigan, Georgia, New

Jersey, South Carolina, Texas and Pennsylvania each at less than 10% (GfK Kynetec, 1998-

2008). These states are also the largest in tenns oftota l acres treated from 1998-2008 . See

Figure 4.

Figure 4. States with the Highest Use-Percent of Total Lbs Applied, 1998 to 2008.

4%

8 0 KlJ*lOMA

• LOUISIANA

o WASHINGTON

D NEWYORK

• MICHIGAN

• GEORGIA

• NEW JERSEY

o SOUTH CAA.OLlNA

• TEXAS

• PENNSYLVANIA

18%

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Non-Agricultural Usage

BEAD reviewed available non-agricultural sources, but no information was found on the use of

terbacil in non-agricultural use sites.

Figure 5. Terbacil Top Crops Usage, 1998·2008

140 ,000 'r-- - - - - - - - - - - - - - - - - - ---,

o Alfalfa

o Peaches

• Apples

iii Sugarcane

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

Over the 1998-2008 time period, usage on sugarcane has decreased from a high ofmore than

50,000 lbs AI to almost none, while the use on alfalfa has remained fairly constant throughout

the same time period. This decrease ofterbacil usage may be due variations in sugarcane

production due to the heavy subsidizations of other sugar-producing countries. In addition,

development of new sugarcane varieties with less tolerance to terbacil may have played an

important role on this decline in terbacil usage. The use on peaches decreased by over 95 percent

between 2007 and 2008. While the use on caneberries was only available for 2006 through 2008,

a small amount ofterbacil use was observed in 2008 only.

BIOLOGICAL ASPECTS RELEVANT TO TERBACIL

Volatility, death of non-target plants due to the herbicide drift, longer residual activity are some

ofthe problems ofthis herbicide (Sinbar® Specimen Label, 2010). Additionally, terbacil should

not be applied to areas where their roots may extend or in locations where the chemical may be

washed or moved into contact with their roots. When terbacil is applied, measures to prevent

drift of dry powder or spray to desirable plants should be avoided. Residual activity is a problem

with terbacil and it comes with the two-year carryover restriction. Crops like corn, oats, wheat,

and squash may be less sensitive to this herbicide, but phytotoxic effects on collards have been

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observed even six months after the application of this herbicide (Southeast Farml'ress, Feb.,

2009).

Resistance Management

Development ofresistance in biotypes of diffe rent weed species has been reported. Velvetleaf

(Abutilon theophrustit; smooth pigweed (Amaranthus hybridus), palmer amaranth (Amaranthus

palmeri), powell amaranth (Amaranthus powettiv; redroot pigweed (Amaranthus retrojlexus). tall

waterhemp, (Amaranthus tuberculatus (syn. rudis}, common ragweed (Ambrosia artemisiifolia),

and lambsquarters (Chenopodium album) are the major weeds found to be resistant to terbacil

(WSSA,20 10). Management of herbicide resistance is necessary to delay and to avoid the

proliferation of resistant weed biotypes. Tillage, crop rotation, and use of tank mix partners and

sequential applications of herbicides with different modes of action are important in this aspect.

HISTORY O F BEAD ASSESSMENTS FO R TERBACIL

Terbacil has not been the subject of any risk mitigation impact assessments developed by BEAD.

However, there have been a few emergency exemption (Section 18) requests from Maryland,

Virginia, Georgia. and Delaware over the years that have been reviewed by BEAD. In all cases

these requests for terbacil were intended for use on watermelon. A RED was completed for

Terbacil in 1998.

DATA NEEDS RELEVANT TO BEAD'S FUTURE WORK ON TERBACIL

Obtaining additional information on the following items would improve BEAD's assessment of

the importance of terbaci l as a herbicide. This assessme nt is likely to be required as part ofthe

registration review ofthis pesticide.

I. Comparative efficacy information of terbacil to similar products registered for similar

uses for apples, alfalfa, and peaches.

2. Information on grower's selection criteria for growth regulator at each crop stage where

terbacil may be used.

3. Terbacil usage data for forestry and terrestrial feed sites and information on effective

alternatives.

4. Reasons for the decline in terbacil usage on sugar cane and peaches.

5. Worker activities that occur in treated fields at the typical time ofterbacil applications.

6. Comparative costs ofterbacil versus other herbicides in identified use sites.

REF ERE NCES

GfK Kynetec, 1998-2008 . Proprietary Data .

Environmental Protection Agency (EPA). 2010 . Section 18 Action Database. Avai lable at:

http://cfpubl .epa.gov/oppref/section 18/searchresult .cfm. Retrieved 8/18/10.

Extoxnet. 2010. Terbacil. Pesticide Information Profile.

http://extoxnet.orst.edulpipslterbacil.htm.

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EPA, 1998. R. E. D. Facts. Terbacil. Publication of the Environmental Protection Agency

http:""'\\'W.epa.gov/oppsrrd IIREDslfactsheetsl003 9fact. pdf

Sinbar Specimen Label. 2010. Tessenderlo Kerley, Inc. Phoenix, AZ 85008, USA.

http://"'\\'W.growercentral.comlUPLOADSIPDFS/sinbar%20label%20(05-07l.pdf

Roberson. R. 2009. SouthEast FarmPress. http://southeastfannpress.com/vegetablestobacco/\'cgctablcs-hcrbicides-02101

WSSA, 2010 . International Surve y of Herbicide Resistant Weeds.

http://ww,,,,,'.weedscicnce.org!SummarvlUspec icsMOA.asp?lstMOAID-=4&FmHRACGroup=Go

Appendix 1: Emergency Exemption Requests for Terbacil

The EPA Section 18 Action Database only retrieves requests from 200 I onward, although

occasionally older requests are available. The following BEAD assessment from 1994 was not

included in the database :

Ali, Ghulam; George Keitt. 1994. Review of Maryland Requests for Emergency Exemption of

Clomazone and Terbacil for Use on Watennelon to Control BroadleafWeeds (DP# 202043;

202044).

There was also a BEAD analysis done for the following assessment which also was not recorded

in the Section 18 Action database .

Zinn. Nicole; Andrew Lee. 2003. Review of a Request for Emergency Exemption of Terbacil in

Georgia for Use on Watennelon to Control Annual Morn ing Glory and Palmer Amaranth (DP #

313717).

EPA Section 18 Action's for Te rbacil

DP BAR CODE(S)

Site Pest Applicant Received Response St atus

FOR HEAD

Date Dat e ASSESSM E/'IiTS,

IE CONDUCTEO

WATERMELON WEEDS DELAWARE 119/1997 518/1997 ISSUED

WATERMELON WEEDS MARYLAND 11/15/1996 5/811997 ISSUED 232026. 232027 WATERMELON WEEDS VIRGINIA 11/18/1996 518/1997 ISSUED

WATERMELON WEEDS VIRGINIA 1012211997 11124/1997 ISSUED

WATERMELON WEEDS DELAWA RE 112711 998 2/6/1998 ISSUED

WATERMELON MORNING MAR YLAND 1122/1998 2/6/1998 ISSUED

GLORY

WATERMELON WEEDS DELAWARE 3116/1999 312511999 ISSUED

WATERMELON MORNING MARYLAND 1127/1999 3125/1999 ISSUED

GLORY

WATE RMELON BROADLEAF VIRGINIA 1/8/1 999 3125/1999 ISSUED

WEEDS

WATERMELON WEEDS DELAWARE 2/1012000 4/312000 ISSUED

WATERMELON WEEDS MARYLAND 2/10/2000 4/312000 ISSUED

7
WATERMELON BROADLEAF VIRGINIA 111912000 4/312000 ISSUED

WEEDS

WATERMELON WEEDS DELAWARE 3/1512001 31281200 1 ISSUED

WATERMELON WEEDS MARYLAND 21512001 3/2812001 ISSUED

WATERMELON BROADLEAF VIRGINIA 1131 /2001 3/28/2001 ISSUED

WEEDS

WATERMELON WEEDS DELAWARE 1/2512002 312712002 ISSUED

WATERME LON WEEDS MARYLAND 211512002 4/412002 ISSUED

WATERMELON BROADLEAF VIRGINIA 2113/2002 4/412002 ISSUED 281291. 281289

WEEDS

WATERMEL ON BROADLEAF VIRGINIA 111312003 2/4/2003 INCOMPLETE -

WEEDS OUTSTANDING

DATA

REQUESTED

WATERMELON BROAD LEAF VIRGINIA 3/1212003 4/1 12003 ISSUED

WEEDS

WATERMELON MORNINGGLORY DELAWARE 41312003 412812003 ISSUED

WATERMELON MORNING MARYLAND 412/2003 4129/2003 ISSUED

GLO RY

WATERMELON BROAD LEAF FLOR IDA 12/312003 3/2212004 WITHDRAWN

WEEDS

WATER..\1ELON WEEDS DELAWARE 2/23/2004 3/26/2004 ISSUED 280592

WATERMELON WEEDS MARYLAND 2/24/2004 3/26/2004 ISSUED

WATERMELON WEEDS VIRGI NIA 3/1512004 3/2612004 ISSUED

WATERMELON WEEDS DELAWARE 113/2005 3/1112005 ISSUED

WATERME LON BROAD LEAF VIRGINIA 111912005 3/11/2005 ISSUED

WEEDS

WATERMELON BROADLEAF MARYLAND 3/812005 6/612005 ISSUED

WEEDS

WATERMELON BROADLEAF GEORGIA 2/1412005 7/15/2005 ISSUED

WEEDS

WATERMEL ON MORNING GEORGIA 1/3112006 3/912006 ISSUED

GLORY &

PALMER

AMARA NTH

WATERMELON ANNUAL VIRGINIA 3/112006 4/612006 ISSUED

BROADLEAF

WEEDS

WATERMELON ANNUAL DELAWARE 3/1512006 4!2512006 ISSUED

BROAD LEAF

WEEDS

WATERMELON ANNUAL MARYLAND 3/17/2006 4!25/2006 ISSUED

BROADLEAF

WEEDS

Source. EPA (2010). BEAD OffiCial Records.

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