UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASH I NGTON , D .C. 20460



### MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: BEAD Che mi cal Profile for R eg ist ration Review: Topramezone (123009) 

### FROM: Co l well Cook, Entomologist

## ~**~** Biological Anal ysis Bra n ch



### THRU : Cynthia Doucoure, Environmental Protection Sp eciali st Science Information and Analysis Branch D erek Berwald, Economist 

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# 1~, Economic Analys i s Branch
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# J**V"~** Bi ological and Economic Analys is Divi s ion (75 Amet Jone s, Chief Biological Analysis Branch Diann Sims , C hi e f Science Information and Analysis Branch Timothy Kiely , Chief 

## (I\_ 

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# ) Economic Analysis Branch 

# '-:J**I~** Bi ologica l and Economic Analy s is Division (7503P) 

### TO: Jose Gayo so , Chemical R ev iew Manager Risk Management and Implementation Branch II Pes tic ide Re-evaluation Divi s ion (7508P)
Product Review Panel date: February 4, 2015

Page 

### 1 of9SUMMARY Toprame zone, a pyrazolone herbicide, was first registered in t he U.S. in 2005 for pre-emergence and postemergence control of broadleaf and grass weeds in field corn, popcorn, and sweet corn. More recent registrations include weed control in Christmas, conifer, and hardwood tree farms, field ornamental production, turf, and non-cropland areas. In addition, this chemical has been registered as an aquatic herbicide. Currently, topramezone is the only p yrazolone herbicide (a subclass of HPPD mechanism of action) in the U.S. The mechanism of action inhibits the Hydro xy Pheny l Pyruvate Dioxygenase (HPPD) enzyme which i s required for carotenoid biosynthesis. Carotenoids are key in the removal of oxygen radicles which can destroy ceUs. Based on available private market research data, topramezone is reported to be used on field and sweet corn during the 2006-2013 time frames. Approxima te ly 19,000 lbs a.i. were applied on average annually to 1.3 million acres of field and sweet corn at an overall average a.i. application rate ofO.Ol lbs a.i. per acre. Approximately 93% of the total pounds oftopramezone applied was to field corn but the percent crop tr eated (the ratio ofbase acres treated to crop acres grown) for field corn was <2.5%, whereas the percent crop treated for sweet corn was 15%. No national level topramezone usage data were found on nonagricultural sites. INTRODUCTION The purpose of this document i s to convey usage information and a broad overview of the pest management roles of topramezone that is beginning to undergo registration review. The anticipated audience consists of the team of EPA staff currently evaluating the registration status of topramezone, and eventua lly the general public. This document builds upon the data BEAD provides in the Screening Level Usage Analysis (SLUA) to Registration Review teams. The document is based on information and data available to BEAD as of December 2014. HISTORY OF BEAD ASSESSMENTS FOR TOPRAMEZONE BEAD prepared a Screening Level Usage Analysis (SLUA) in December 2014 that provided average percent crop treated (PCT) values for field corn (<2 .5% ) and sweet corn (I 5% )
. The average annual pounds a.i. applied was 10,000 lbs a.i. to field corn and 1,000 lb s a.i. to sweet corn. These data are based on available p ublic and private market research data. BEAD also reviewed submissions for a Public Interest Finding from the initial registration in 2005. The review found that topramezone would have value to corn growers by increasing flexibility with a new mode of action
. Thi s would be useful as a resistance management tool, as well as reduced risk of crop-damaging interaction with some insect icide s (Zinn, 2005).
COMMON FORM U LATIONS AND APPLICATION METHODS Topramezone is formulated as suspension (flowable) and emulsifiable concentrates.
Page 2 of9USE SITES Agr icul tural Use Sites Topramezone i s regi s tered for use on field corn, popcorn and sweet corn, and during the fallow period
. It is also used on nurse ry stock, sod tur f farm s, forest trees , and Christmas tree plantation s. Non

- Agric ultural Use S ites: Topramezone is re g i stere d for use in aquati c areas , including pond s , lakes , reservoir s , mar shes , wetlands , bayous , drainage ditches, canal s and s low-moving or quie sce nt bodies of water. It i s a lso u se d on ornamental lawns and turf , including recrea tional area and residential lawns.
TOPRAMEZONE USAGE Agricultural Us ag e Tre nd Based on available p ri vate market research, topramezone i s reported to be used predominantly on fie ld and sweet co rn in the U.S. During the 2006

- 2013 time frames , app roximate ly 19,000 lbs a. i. were applied o n average annually to 1.3 milli o n acres of field and sweet co rn at an overall ave rage a.i. application rate ofO.Ol lbs a.i
. per a c re. Us e of topramezone on field corn, in terms of pounds a.i. applied , ha s inc reased si nce its r eg is tration in 2005 , while use on sweet corn has remained relatively low as shown in Figure 1. Some of this reflects the relative ly low acreage of sweet corn rel ative to fie ld corn; as mentio ned above , the SLUA indi cates a greater percentage of sweet corn is treated with topramezone . Similar trends were found fo r the tota l area treated. Approximatel y 93 % of the total pounds a.i. app li ed was reported to be used on fiel d co rn as s hown in T able 1. H owever, th e average a.i. applicat i o n rate s and labeled application rates were the same for both fie ld and sweet corn.

Page 

### 3 of9

### Figure 1. Topramezone Pounds AI. 

### Applied on Field and Sweet Com 2006

- 2013 50,000

0 20 0 6 2007 2008 2009 2010 2011 2012
. 2013 Year

..,._ Corn ..,._ S weet Corn Source : Proprietary Data , 2006-20 1 3


### Figure 2. Topramezone Total Area Treated (In Acres): Field and Sweet Com, 2006-2013 3,000,000

'0 Q) -m Q)**~** ro Q)**~** ro 0 1-

0 2006 2007

Source: Proprietary Data , 2006-20 13 2008 2009 2010 2011 2012 2013 Year

..._ Co rn ..,._ S weet Corn



### Page 4 of9T bl 1 T a e opramezone 

### T C op rops, 2006 2013


### - Percentage of 

### Percentage of Labeled Max App

Total Lbs

A. l. of Total Area Avg A.I. Rate Rate per Topramezone Treated with (lb a.i./acre) App lication Top Crops Applied Topramezone Field Corn 93% 94 % Sweet Corn 7 % 6 % Sourc es: Propnetary Data , 2006-2013 T o pramezone LUIS Report, EPA, 2015
Topramezone Top States, 2006-2013 (lb a.i./acre) 0.01 0.02 0
. 01 0.02

During th e 2006-2013 time frame , topramezo ne is reported to be used in 18 s tates. However , in term s of the percent of tota l pounds a.i. applied, toprame zone is u sed predominantly in the sta tes oflowa (30 % ), Illinoi s (18 % ), and Indian a (14%) followed by Minnesota (10%) and Nebraska (9%) as s hown in Table 2. Toge ther, these s tates constitute over 8 0 % of the total topramezon e used during this period.
T bl 2 T

a e opramezone 

### T S op tates, 2006 2013

- State Share of State Share of Total Lbs A.I. of Total Area

Topramezone Treated with Avg A. I
. Rate Top States Applied Topramezone (lb a.i./acre) Iowa 28 % 31% 0.01 Illinoi s 18 % 17% 0.02 Indiana 15 % 13 % 0.02 Nebraska 12% 11% 0.01 Other 27% 28% 0.01-0.02 *Other s tates include CO , ID , KS , KY , MN , MO , ND , OH, OR , PA , SD , TX , WA, and WI. So urce: Prop ri etary Data , 2006-2013
Agricultural Use Intensity of Topramezone Use in the U.S. Another mea s ure of u s age is th e use intensity. In this analy s i s , th e u se inten s ity is expressed a s the average annual amount (in pounds) of th e ac tive ingredient applied per 1 ,000 acres of crop acres grown. This differ s from the application rate, which i s expressed as the pounds a.i. applied per treated area . Figure 3 spatially represent s topramezone 's higher use inten s ity in the U.S. in Iowa and Indiana, which i s driven by production of field corn and in Illinois, Minnesota, and Nebraska , which is driven by production of field and s weet corn. The high er u se intensity in South Carolina and Was hing ton results from low crop acres grown within th e s tates. For more information on Figure 3, s ee Appen dix A. Page 5 of9

### Figure 3. Annual Average Agricultural Use Intensity of Topramezone (2009

- 2013)
.

Pounds Active Ingredi ent per 1 , 000 Crop Acres Grown 0No0 ata < 0 .015 0 01 5 -00 25

- 0 025

- 0
. 095

- 0
. 095

- 0
. 25

- > 0
. 25 (Source: Proprietary Data, 2009-2013)

Non-agricultural Usage The avail ab le publi c and private database s on nonagricu ltural uses did not report national lev e l usage of topramezon e.

Page 6 of9

### BIOLOGICAL ASPECTS RELEVANT TO TOPRAMEZONE Topramezone provides pr eemergence and postemergence weed co ntrol (Shaner, 20 10). Topramezone is in the group of herbicides known as pyrazo lon es and is in Group 27 of the Weed Science Society. These herbicides have the mechanism of action of inhibiting the HPPD enzyme, which is required for carotenoid bio synthesis. Carotenoids are key in th e removal of oxygen radicl es which can destroy cells. The primary u se of topramezone is in field com where it is used to control broadleaf weed s s uch as co mmon waterhemp, lamb s quarters and so me pigweeds, as well as grass weeds suc h as the various types of fox tail s. In sweet com this herbi c ide i s used to control many of the same broadleaf and grass weeds as well as broadl eaf weeds suc h as redroot pigweed and grasses such as wild proso millet. In November of 2013, topramezone was federally registered as an aquatic h erbicide. Other registration s in 2014 a ll ow for topramezone postemergence weed control in Christmas, conifer, and hardwood tree farms, field ornamental production, turf, and non-cropland areas. 

### ROLE OF TOPRAMEZONE IN PEST MANAGEMENT Cur rently topramezone is the only pyrazolone herbicide in t he U.S., a type of HPPD inhibi tor. This new mode of action is useful for rotation with other herbicide s with different modes of action for managing weeds, such as pigw eed s, lamb squarters , and foxtails, especially in sweet co m and pop corn, which have fewer herbi c ide options (Zinn , 2005). Growers of sweet com are co ncerned with resistance to triazine and ALS inhibitors; in addition certain sweet corn varieties are sensitive to some herbicides (Zinn, 2005). Topramezone play s a role in weed management in the se crops becau se of its uniq ue mode of action. Topramezone is the only HPPD herbicide registered for aquatic weed co ntrol and can be used as part of a resistance management program (Aquatic Plant Management Society, In c., 2- 14).



### INFORMATION THAT MAY BE USEFUL FOR BEAD'S FUTURE WORK ON TOPRAMEZONE The Agency currently does not have complete information on topramezone. Obtaining the following u sage information may improve future assessments conducted by the Agency related to the use and importance of topramezone:
• Aquatic areas: usage data (pounds a.i. applied per year , maximum rate of application, number of applications per year) • Agricultural and nonagricu ltural u ses including nursery stoc k , Christmas and forest tree plantings, ornamental lawn s and tur f: usage data (pounds a.i. applied per year, maximum rate of application, number of applications per year)

Page 7 of9

### REFERENCES Aquatic Plant Management Soc iety, Inc. 2014. Herbicide res istance stewardsh ip in aquatic pl ant management. Avai lable at: http:/ /apms.org/wp/wp-content/uploads/20 14/04/Herbicide

Resistance

- Stewardship

- in

- Aguatic-Plant

- Management.pdf
. Accessed: February 4, 2015. EPA, Topramezone Screening Level Usage Analys is (SLUA) , August 2014 Proprietary Data, 2006-2013 Shaner, DL. 2014. Herbicide Handbook Tenth Edition. Weed Sci
. Soc
. of Am. 810 E
. lOth Street, Lawrence, KS 66044-8897. U.S.A. Zinn, Nico le. Evaluation of Public Interest Documentation for the Conditional Registration of T'opramezone on Field Com, Sweet Com , and Pop Com, D313195. US EPA , May 13,2005.

Page 8 of9APPENDIX A
The map included herein is primarily for the use of the risk assess ors in the Environmental Fate and Effects Division. The map provides a very broad geographical view of the average annual amount (in pounds) of the active ingredi ent app lied per 1,000 acres of crop acres grown. These data are included in the maps beca use risk assessors are interested in the amount of a pesticide us ed across agricultural land. The calculated values presented in the map are not equivalent to an application rate (lb ail A). The data used to make these maps have several limitations. Any interpretation of the maps should consider the underlying data and the associated limitations carefully. The numerator (annual average pounds applied) i s bas ed on private market surveys of pesticide use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys cover about 60 crop s and are targeted in states that produce the majority of the crop. Although the surveys capture most of the use of a particular active ingredient in agriculture, there are several limitations to these surveys . • States with minor production of a surveyed crop are not samp led • Not all types of pe sticides are surveyed in every crop in every year • Many specialty crops w ith very small acreages are not included in the s urv ey The result of these limitations is that states that show no usage may actually have a small amount of the active ingredient b eing used. In some cases the displayed use inten sity may be di storted because the surveyed crops and the reported pesticide usage may not accurately represent th e actual pe s ti c ide usage on the crops produced in the state. The denominator ( I ,000 crop acres grown) was also obtained from the same private market survey database. The "Crop Acres Grown" variab le represents the total acres grown in a given state of all of the surveyed crops. This value is independent of pesticide u sage and pesticide registration. It is important to note that the surveyed crop s (about 60) are samp led from s tates that are major producers of each crop . Therefore, there are cases where the ac tual cro p acreage in a state is higher than that reported by crop acres grown in the survey becau s e either that state and/or crop was not included in the survey. The read er s hould pay particular attention to the figure legend s and reali ze that a map prepared for a particular chemical is not directly comparab le to a map prepared for a different chemical a s the legend bins will l ikely be different.

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