UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460 

## MAY 0 1 2014

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### SUBJECT: BEAD Chemical Profile for Registration Review: Imazaquin (128848) and Imazaquin, monoammonium salt (128840) FROM:

THRU: Carl Chen, Biologist 

### {__wJ(

## ~ Biological Analysis Branch CynthiaDoucoure, Environmental Protection Specialist C

## ~~ Science Information and Analysis Branch Michelle Ranville, Economist 1 /}(lf/ 

### p;---6) Economic Analysis Branch 

## U**~** Biological and Economic Analysis Division (7503P) Arnet Jones, Chief /) d 1...-"'7"-.:.A 

### Biological Analysis Branch

## ~/" Diann Sims, Chief

## 41-"~**~.4.** Science Information and Analy s Branch Timothy Kiely, Chief

# ~**~** Economic Analysis Branch 

### \J....A... Biological and Economic Analysis ivision (75 ) TO: Wilhelmena Livingston, Chemical Review Manager RiskManagement and ImplementationBranch V Pesticide Re-evaluation Division (7508P)


### Product Review Panel date: April16, 2014

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### INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofimazaquin and eventually the general public. This document builds upon the dataprovided by the Biological and Economic Analysis Division (BEAD) in the Label DataReports and the Screening Level Usage Analysis (SLUA) to Registration Review teams. The document is based on information and data available to BEAD as ofMarch 2014. Imazaquin, an imidazolinone herbicide, was first registered in 1986. There are currently eight Section 3 registrations and one 24(c) registration for imazaquin (128848) and nine Section 3 registrations for imazaquin, monoammonium salt (128840). A Report of the Food Quality ProtectionAct(FQPA) Tolerance ReassessmentProgress andRiskManagement Decision (TRED)for Imazaquin was completed in December 2005. EPAfound that the tolerance for imazaquin meets the FQPA safety standards. Also, perthe TRED, since the ecological and occupational assessments were originally conducted when imazaquin was first registered, no further ecological or occupational assessments were conducted as part ofthe TRED.


### IDSTORY OFBEAD ASSESS:MENTS FORIMAZAQUIN BEAD prepared a Screening Level Usage Analysis (SLUA) in 2014 which shows that an average of50,000 lbs a.i. ofimazaquin was applied to soybeans from 2004-2012 and that the average percent crop treated was less than one percent. BEAD has not conducted any benefits assessments for imazaquin and no Section 18s have been issued for this chemical. However, a lack of Section 18s does not indicate a lack ofbenefits for the chemical.


### COMMON FORMULATIONS AND APPLICATION :METHODS Imazaquin is commonly formulated as water dispersible granules, wettable powders, soluble concentrates, and emulsifiable concentrates. Imazaquin canbe applied using aerial or ground applications. 

### USE SITES Agricultural Use Sites: Imazaquin and imazaquin monoammonium salt are registered for use on soybeans and sod farms. Non-Agricultural Use Sites: Imazaquin and imazaquin**monoammoniu~** salt are registered for use on landscape ornamentals, residential and commercial lawns and turf, 1**~s** well as golfcourses. (1 

### ' ( Page 2 of8IMAZAQIDNUSAGE Agricultural Usage Trend: lmazaquin Use on Soybeans According to proprietary market research surveys, imazaquin use on soybeans in the U.S. in terms ofpounds a.i. applied and total area treated decreased substantially since 1998 as shown in Figures 1 and 2 below. During this time, an average of 132,000 lbs a.i. was applied to 1,530,000 acres at an overall average a.i. rate of0.09 lbs a.i. per acre. Figures 1 and 2 depict the total of imazaquin and its monoammonium salt. Product specificusage data shows that the same downward usage trend applies to both active ingredients.**~** .!!! 

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### "'(S**,~** nSS nSS**~ ~** **~** Year Figure 1. Imazaquin Use on Soybeans: Pounds AI Applied, 1998-2012 Source: Proprietary Data, 1998-2012

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### 3 of8 - soybeans- soybeans

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### Y. {') {')**~ ~** **~ ~** **~ ~** **~ ~**  '\.(J**~ ~** **'\.~ ~**  Year Figure 2: Imazaquin Use on Soybeans: Total Area Treated Applied, 1998-2012 Source: Proprietary Data, 1998-2012 Agricultural Usage oflmazaguin on Soybeans inRecent Years, 2008-2012 During the time period from 2008-2012, an average of56,000 lbs a.i. was applied to 613,000 acres at an overall average a.i. rate ofapplication of0.09 lbs a.i. per acre. The states with the most usage interms ofthe percentage ofthe total pounds a.i. applied during this time were Indiana (37%), Ohio (33%), and Michigan (11%) as shown in Table 1below. The average a.i. rates ofapplication and number ofapplications were similar across the top states
. T bl 1 I

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## ·u mazaqum se on . M . Stat 2008 2012 

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### - State Proportion of Avg A.I. Rate Avg#ofApps Total Lbs A.l. ofApplication Applied Indiana 37% 0.09 1 Ohio 33% 0.10 1 Michigan 11% 0.09 1 Other* 19% 0

.05-0.12 1 *Other states include AR, IL, lA, KS, KY, LA, MS, MO, NE, NC, OK, PA, and VA Source: Proprietary Data, 2008-2012

Page 4 of8Agricultural Use Intensity ofhnazaquin on Soybeans in the U.S. Another measure ofusage is the use intensity. In this analysis, the use intensity is expressed as the average annual amount (in pounds) ofthe active ingredient applied per 1,000 acres ofcrop acres grown. This differs from the application rate, which is expressed as the pounds a.i. applied per treated area. Figure 3 spatially represents imazaquin's use intensity in the U

.S. on soybeans, which was greatest in Ohio, Indiana, and Michigan during the 2008-2012 time frame. For more

. information about this map, see Appendix A.

Pounds Active Ingredient per 1.000 Crop Acres Grown CJNoData CJ <OD5

. 0.05-0

.17 0.18- 0

.63

- >0

.83 

### Figure 3. Annual Average Agricultural Use Intensity ofImazaquin, 2008-2012 Source: Proprietary Data, 2008-2012 Non-Agricultural Usage BEAD reviewed available private market research survey data and found that there is reported use of 15,000 lbs a.i. of imazaquin in the turfand ornamental market, which includes 9,000 lbs a.i

. applied by lawn care operators and 6,000 lbs a.i

. applied to landscapes in the mostrecent year available (Proprietary Data). No other reports ofimazaquin use were found for the nonagricultural market.

Page 5 of8BIOLOGICAL ASPECTS RELEVANT TO IMAZAQUIN Imazaquin is an imidazolinone herbicide. The mechanism ofaction ofthis chemical family is to inhibit acetolactate synthase (ALS) classified by the Herbicide Resistance Action Committee (HRAC) and coded as HRAC Group B. It is also listed by the Weed Science Society ofAmerica (WSSA) as a WSSA Group 2 herbicide. Group 2 orALS herbicides are associated with the highest rank (3) ofrisk on occurrence ofresistance (WSSA, 2010). Some genera composed of weeds targeted by imazaquin such as pigweed and barnyardgrass are also associated withthe highest rank (3) ofresistance risk (WSSA, 2010; Heap, 2010).

ROLE OF IMAZAQUIN IN PEST MANAGEMENT Imazaquin is a broad-spectrum herbicide that can be applied preplant incorporated, preemergence, orpostemergence in soybeans. It is registered to control a number ofimportant weeds in soybeans including cocklebur, common lambsquarters, morning glory, redroot pigweed, velvetleaf, barnyard grass, and foxtail. The use ofimazaquin in soybeans declined significantly but has remained steady since 2004. BEAD's SLUA showed that the average percent crop treated for soybean from 2004-2012 was less than 1percent. However, the most recent available usage data shows that imazaquin use on soybean in the Great Lakes region (Ohio, Michigan, and Indiana) could be higherthan the average with percent crop treated reaching up to nine percent (Proprietary Data, 2010-2012). In Michigan, imazaquin is recommended to control broadleafweeds and to suppress yellow nutsedge 

### in soybeans (Crop Profile for Soybean 

### in Michigan, 2002). Imazaquin is registered for non-agricultural uses to control nutsedge and other annual or perennial weeds. In Arizona, nutsedge is a very troublesome weed in golfcourse and parks turf, and imazaquin is recommended for control ofpurple nutsedge in bermudagrass turf(Kopec, 2000). Imazaquin is also currently registered under section 24(c) ofthe Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) to control red rice in soybeans in Louisiana. Although EPA's proprietary data does not show any recent usage ofimazaquinon soybeans in Louisiana, the maintenance ofthe registration could indicate that the chemical is important for this use. In general, usage ofimazaquin on soybean, the only registered agricultural field crop use, has decreased significantly since 1998. However, the fact that usage has remained stable since 2004, especially in the Great Lakes region, and the recommendations for control ofnutsedge in soybean and non-agricultural uses could indicate important niche uses for this chemical and its monoammonium salt.

Page 6 of8INFORMATION THAT MAY BE USEFUL FORBEAD'S FUTURE WORK ON IMAZAQUIN The Agency currently does not have certain important information on imazaquin. Obtaining the following information may improve future assessments conducted by the Agency related to the use and importance ofimazaquin:

• Usage information (e.g., acres treated, lbs applied, application rates, target pests) on ornamental lawns and turf, including golfcourses and sod farms. • Resistance management informationrelated to the use and importance ofimazaquin in soybean production.

REFERENCES Crop Profile for Soybean in Michigan. 2002. Online: http://www.ipmcenters.org/cropprofiles/docs/MISoybean.pdf

. Accessed March 2014. EPA. 2005. Report ofthe Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk ManagementDecision (TRED) for Imazaquin. Online: http://www

.epa.gov/oppsrrd1/REDs/imazaquin tred.pdf

. EPA. 2005. Screening Level Usage Analysis for Imazaquin. January 28, 2005. EPA. 2014. Imazaquin (128848) Screening Level Usage Analysis (SLUA). March 5, 2014. Heap, I. 2010. International Survey ofHerbicide Resistant Weeds. Online: http://www.weedscience.org

. Accessed March 2014. Kopec, DM. 2000. Nutsedge Control in Turf. Online: http://turf.arizona.edu/ccps700.htm. Accessed March 2014. Proprietary Data, 1998-2012. WSSA, 2014. Summary ofHerbicide Mechanism ofAction. Weed Science Society ofAmerica. Online: http://wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf. Accessed March 2014.

Page 7 of8APPENDIX A The map included herein is primarily for the use ofthe risk assessors in the Environmental Fate and Effects Division. The map provides a very broad geographical view ofthe average annual amount (in pounds) ofthe active ingredient applied per 1,000 acres ofcrop acres grown. These data are included inthe maps because risk assessors are interested in the amount ofa pesticideused across agricultural land. The calculated values presented in the map are not equivalentto an application rate (lb ail A). The data used to make these maps have several limitations. Any interpretation ofthe maps should consider the underlying data and the associated limitations carefully. The numerator (annual average pounds applied) is based on private market surveys ofpesticide use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys cover about 60 crops and are targeted in states that produce the majority ofthe crop. Although the surveys capture most ofthe use ofa particular active ingredient in agriculture, there are several limitations to these surveys.

• States with minor production ofa surveyed crop are not sampled • Not all types ofpesticides are surveyed in every crop in every year • Many specialty crops with very small acreages are not included inthe survey Theresult ofthese limitations is that states that show no usage may actually have a small amount ofthe active ingredient being used

. In some cases the displayed use intensity maybedistorted because the surveyed crops and the reported pesticide usage may not accurately represent the actual pesticide usage on the crops produced in the state. The denominator (1,000 crop acres grown) was also obtained from the same private market survey database. The "Crop Acres Grown" variable represents the total acres grown in a given state ofall ofthe surveyed crops. This value is independent ofpesticide usage and pesticide registration. Itis important to note that the surveyed crops (about 60) are sampled from states that are major producers ofeach crop. Therefore, there are cases where the actual crop acreage in a state is higher than that reported by crop acres grown in the survey because either that state and/or crop was not included in the survey. 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 as the legendbins will likely be different.

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