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

### APR 09 1tl14

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION
MEMORANDUM

SUBJECT: FROM:

THRU: BEAD Chemical Profile (BCP) for Registration Review: Mesotrione (122990) Sunil Ratnayake, Ph.D., Biologist

# ~MD**~** /1 

# n Biologica!AnalysisBranch 

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### ~**~** Don Atwood, PhD., Entomologist 

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# ?J7 vb Science Information and Analysis Branch Stephen Smearman, Economist 

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_ .. __ Economic Analysis Branch**~** Biological and Economic Analysis Division (7503P) Arnet Jones, Chief Biological Analysis Branch Diann Sims, Chief 

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Science Information and Analysis Branch Timothy Kiely, Chief

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# f Economic Analysis Branch 

# -._J**vv'--~0** Biological and Economic Analysis · ision (7503P) TO: Jolene Trujillo, Chemical Review Manager Pesticide Re-evaluation Division (7508P)

Peer Review Panel date: March 5, 2014

Page 1SUMMARY 

### Mesotrione was first registered in

### the U.S. in

### 2001 and itbelongs to the triketone family of herbicides. It

### is a selective herbicide registered for control ofbroadleafweeds in

### many agricultural and non-agricultural use sites. Mesotrione can be applied as pre-emergence and post-emergence treatments in agricultural and non-agricultural use sites. The mechanism of action ofmesotrione is the inhibition of4-hydroxypenyl-pyruvate dioxygenase ( 4-HPPD), an enzyme found in plant species and the interference ofthis enzyme leads to the destruction of chlorophyll and killing the susceptible plants. Mesotrione is an important tool used 

### in resistance managementprograms. Itprovides an effective control ofseveral key weed species with resistance to glyphosate, triazines, protoporphyrinogen oxidase (PPO) and acetolactate synthase (ALS) inhibiting herbicides. The major agricultural use sites include; blueberries, caneberries, cranberries, rhubarb, pop com, field com, sweet com, okra, asparagus, millet, 

### oats, sugarcane, sorghum, and soybeans. The registered non-agricultural use sites include; lawns, ornamental turf, 

### ornamental flowering plants, and recreational areas. According to the publicly available usage information, the highest usage, in terms 

### oftotallbs applied and total acres treated ofthis herbicide was on com.

INTRODUCTION 

### The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pest management roles and quantitative usage information for mesotrione. The BCP includes summaries ofprevious BEAD products and available public and/orprivate use and usage data 

### for mesotrione to describe the role ofthis chemical in pestmanagement. Additional information on use is available inthe Mesotrione PRD Label Data Report provided in the public docket for this chemical. Information provided in this BEAD Chemical Profile (BCP) may be used by stakeholders (e.g., users and registrants), OPP risk assessors, and OPP risk managers, and the general public during the Registration Review process ofthis pesticide.

AGRICULTURAL USE SITES 

### Mesotrione is registered for use on blueberries, caneberries, cranberries, rhubarb, popcorn, field com, grass grown for seed, sod, sweet corn, okra, asparagus, 

### millet (pearl and proso), oats, sorghum (grain 

### and sweet), sugarcane, flax, and soybeans.

NON-AGRICULTURAL USE SITES 

### Non-agricultural use sites which are labeled for Mesotrione application include lawns, ornamental turf

### (i.e. commercial lawn, golfcourses, cemeteries, and athletic fields), ornamental flowering plants (cuphea), and recreational areas.

Page2FORMULATIONSAND APPLICATIONMETHODS Mesotrione has seven formulations. These are granular, waterdispersible granules, emulsifiable concentrate, soluble concentrate, solution-ready to use, pressurized liquid, and soluble concentrate/solid. Mesotrione is applied pre- andpost-emergencethrough ground or aerial application equipment

HISTORY OFMESOTRIONE AND BEAD PRODUCTS Mesotrione was first registered for use inthe U.S. in 2001 by Syngenta Crop Protection Inc. underthe Callisto® product label. Inthe past five years, BEAD conducted twojustification reviews for the extension ofthe exclusive use period for mesotrione (USEPA, 2010 and 2011). Syngenta Crop Protection Inc. submitted a petition to the Agency, in January 2009 requesting the exclusive data use period be extended for three additional years for data submitted in support ofthe mesotrione registration. Syn:genta provided infonnation for 14 crops and BEAD detennined that 7 crops metthe criteria which was that mesotrione was needed because there were insufficient alternatives available andfor managing pestresistance. Following BEAD's review in March 2010, the Agency granted extension ofexclusive data use period for 2 additional years and the new expiration date ofthis extension period was June 2013. A total ofnine minor crops were needed to meet the criteria for granting maximum duration of3 years for the extension ofexclusive data use period. InApril2011, Syngenta submitted infonnation onfour additional crops; blackberry, raspberry, okra, and lingonberry for consideration. BEAD reviewed submitted infonnation and detenninedthat ofthese four minor crops, okra and blackberry meet the criteria for extension of exclusive data use period because mesotrione was needed in managing pest resistance to other alternatives for these two crops. There have beenno Emergency Exemption reviews conducted by BEAD for mesotrione inthe last 

### 5 years. Furthermore, there are no active Emergency Exemptions for mesotrione.

MESOTRIONE USAGE Agricultural Usage Usage ofmesotrione and number ofacres treated both showed a steady increase from registration in 2001 through 2007 (Figure 1). After 2007, mesotrione usage (both interms ofpounds applied and

### total areatreated) exhibited a slight decline buthad reached the previous usage level by 2011. Usage further increased in2012 and appears to indicate a trend ofincreased mesotrione usage. The increase inmesotrione usage on com acreage may be due 

### to its use inresistance management (especially glyphosate resistance management).

Page33.000.000

.

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# -- ---.-**----~---~----,--....,.--____,** 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Source: Proprietary Data, 2008-2012 Fi 2. National Mesotrione Us e (Acres Treated) from 2001 to 2012.

30,000,000 .---------------·-----------

-TotalArea Treated

. (acres)

--- ····--- 

### --·---------.,.----- 

## L 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012**-----~-~~~~----** Souree: Proprietary Data, 2008-2012

A review oftotal mesotrione usage data for the last

### 5years indicates that the primary use site is com, accounting for approximately 98%ofbothtotallbs applied and total acrestreated (Table 1). Table 2 indicates that ofthe crops withhighest mesotrione use, field comrepresentsthe highestpercent crop treated interms ofacres grown and acres treated at 20.2%.

Page4Table 1. Crop(s with the**Hi~est** Use ofMesotrione (2008-2012) Crop LbsAI o/o of Total TotalAcres % ofTotalAcres (l,OOO's) Mesotrione Lbs Treated Treated with Applied (1000's)* Mesotrione Field Com 9,910 97.6 90,449 97.7 *Total Acres Treated sums all acres treated for a crop, mcluding those acres that receive multiple treatments. Source: Proprietary Data, 2008-2012
Table 2. PercentCrop TreatedwithMesotrione for specific crops based on total acres KAu"

.. and total acres treated (2008-2012) Crop CropAcres Grown TotalAcres Treated Percent Crop Treated (l,OOO's) (l,OOO's)* Field Com 447,630 90,449 20.2

Sorghum 31,350 1,633 5.2 Sweet com 2,745 472 17.2 *Total Acres Treated smns all acres treated for a crop, mcludmg those acres thatreceave multiple treatments. Source: Proprietary Data, 2008-2012
Table 

### 3 indicates states with highest usage ofmesotrione in terms oflbs 

### ai. applied and acres treated. Iowa, Illinois and Nebraska are the only states where percent lbs a.i. applied and percent acres treated exceed 1 0% ofnational usage. Table 3. States with Highest Use ofMesotrione (2008-2012) State o/o ofTotal State % ofTotal Acres Mesotrione Lbs Treated with Applied Mesotrione* lllinois 15.8 Iowa 16.7

Iowa 13.4 lllinois 15.7 Nebraska 13.1 Nebraska 12.7

Indiana 8.3 Minnesota 8.8 Kansas 7.8 Kansas 7.7 Wisconsin 7.1 Indiana 7.2 Minnesota 6.5 Wisconsin 6.1 *Total Acres Treated smns all acres treated, mcludmg those acres that receave multiple treatments. Source: Proprietary Data, 2008-2012
AwlicationRates and Methods The average mesotrione application rate is highest for sweet com at 0.128 lbs a.i.lacre, as shown in Table 4. However, most U.S. treated acreage, field com, is treated at a slightly lower application rate of0.110 lbs a.i./acre.

PageS

### T bl 4 Mesotrione a e • 

## u seon T C op_ rops: Average A.I Ra 2008 2012 

# . te, 

# - Average TotalLbs Average Total Acres Avg. A.I. Rate Crop Treated (1000's) (l,OOO's)* (lbs a.Uaeres) Com 1,982 18,090 0.110 Sorghum 37 327 0.114 Sweet com 12 94 0.128 *Total Acres Treated sums all acres treated for a crop, mcluding those acres that rec:etve multiple treatments. Source: Proprietary Data, 2008-2012
Table 

### 5 provides average mesotrione application rate by state. Highest application rate, 0.128 lbs a i./acre, is used in Indiana and Wisconsin. However, the rate in Indiana is entirelybased on usage on field com while the rate in Wisconsin represents the combined usage rates for field com (0.127lbs ai.lacre) and sweet com (0.152lbs ai.lacre). Lowest application rate is for field com in Iowa, 0.088 lbs aiJacre. 

### T bl 5 M

a e • esotrione U . T Sta sem op tes: Avera e A.I 

### Rat 2008 2012 

# . te, 

# - State Average TotalLbs Average Total Avg. A.I. Rate Applied Acres Treated (l,OOO's) (l,OOO's)* (lbs a.Uaeres) Illinois 320 2,908 0.110

Iowa 272 3,100 0.088 Nebraska 266 2,359 0.113

Indiana 169 1,324 0.128 Kansas 158 1,428 0.110 Wisconsin 144 1,130 0.128 Minnesota 131 1,629 0.081 *Total Acres Treated sums all acres treated, mcluding those acres thatrecetve multiple treatments. Source: ProprietaryData, 2008-2012 According to proprietary data, broadcast application accounts for 98% ofmesotrione lbs applied and acres treated. Timing ofmesotrione application is evenly splitbetweenpre-plant/emergence and post emergence. Mesotrione can be applied twice a year at the maximum label application rate of8 fl oz/acre. In addition, custom application accounts for 39.6% ofacres treated, fanner application 59.8% ofacres treated, and aerial application accounts for less than 1% ofacres treated with mesotrione.

Page6Geographic Distribution ofMesotrione Use Mesotrione use is reported inthe**m~ority** ofstates with varying level ofuse intensity (Figme 3.) Use inthe western U.S. is limited to Oregon and Washington and reflects lowuse intensity. Regardless ofstate orusage intensity, usage on this map primarily reflects mesotrione application in field comproduction. Only in Oregon is mesotrione use solely attributed to sweet comproduction. Differences inusage intensity for mesotrione in the central and easternUnited States is largely the result ofdiffering levels ofweedpressures and target weed resistance by state. Formore information aboutthis map, see Appendix A. Figure 3. Annual average agricultural use intensity ofMesotrione (2008-2012).

Pounds Active lngreclent per 1.000 Crop Acres Grown c:JNoDoll**s;~;.; l**  <22 lmlllll22. 82

' 6.3-10.0 -10.1-18.0**-~16.0**

Non-Agricultural Usage Datais not available for mesotrione use in non-agricultural sites.

Page7BIOLOGICALASPECTS RELEVANT TOMESOTRIONE 

### According to the Weed Science Society ofAmerica (WSSA) classification ofherbicides, mesotrione belongs to 

### the group oftriketone herbicides (Group 27) (WSSA, Undated). Mesotrione is 

### a selective and systemic herbicide registered for control ofbroadleafweed species in

### many agricultural and non-agricultural use sites. This herbicide can be applied as preemergence and post-emergence treatments and it provides a wider application window for control ofannual broadleafweeds. The mechanism ofaction ofmesotrione is 

### the inhibition of4- hydroxypenyl-pyruvate deoxygenase ( 4-HPPD), an enzyme found in 

### plant species (WSSA, Undated). Inhibition ofthis enzyme leads to 

### the destruction ofchlorophyll in leaves resulting the death ofsusceptible plants (EPA Fact Sheet, 2001). Weed species that can be 

### controlled by applications ofmesotrione, include common cocklebur (Xanthium strumarium), 

### velvetleaf (Abutilon theophrasti), 

### common lambsquarters (Chenopodium album), 

### species ofsmartweed (Polygonum 

### spp.) and giant ragweed (Ambrosia trifida) 

### (Herbicide Handbook, 2007). When mesotrione is 

### applied as pre-emergence treatment, it is absorbed through the roots and dry 

### soil conditions following the application may reduce the pre-emergence activity. Furthermore, application ofatrazine and mesotrione as a mixture has 

### shown a synergistic effects on controlling certain 

### broadleafweeds such as wild radish (Raphanus raphanistrum)(Michael et 

### al., 2012) and Canadathistle (Cirsium arvense) 

### (Gregory et 

### al., 2004). If

### mesotrione is applied as a post-emergence treatment it is absorbed through the weed foliage. Only one post-emergence application ofmesotrione can be made ifmesotrione is applied as a pre-emergence treatment and according to 

### the product label, not more than 

### 2 application ofthis herbicide can be made per 

### season. On 

### corn, the recommended maximum application rate per year is 0.24lb 

### ail A (Callisto•, Product Label).

ROLE OFMESOTRIONE IN PEST MANAGEMENT 

### Mesotrione is registered for the control ofannual broadleafweed species in many agricultural and non-agricultural use 

### sites. It can be 

### applied as 

### pre-emergence and post-emergence treatments and this herbicide provides a wider application window for the control ofannual broadleafweed species. Mesotrione is not effective on most grass weed species and pre

### emergence orpost-emergence grass herbicides can be tank 

### mixed with mesotrione to provide a broad spectrum 

### ofweed control including the control ofgrass weeds. Also, mesotrione can be used 

### in combination with bum-downherbicides to 

### provide an additional bum-down effect and a residual weed control in some crops such as field com, seed 

### corn, yellow popcorn, and sweet 

### com. Mesotrione is an

### importanttool that can be used in

### resistance managementprograms to provide an effective control ofseveral key weed species resistant to 

### glyphosate, triazines, and acetolactate synthase (ALS) inhibiting herbicides (Rechards et al., 2002). According to 

### the publicly available information, biotypes ofonly two weed species: Palmer amaranth, (Amaranthuspalmerz) 

### and Common waterhemp (Amaranthus tuberculatus (syn. Rudis) 

### have developed resistance to 

### the mechanism ofaction ofmesotrione (Weedscience.org, Undated). The usage information ofmesotrione on minor 

### crops is available only on asparagus, blueberries, and caneberries. An

### average of5%total 

### acres ofasparagus and caneberries are 

### treated with PageS

### mesotrione. Similarly, only I0% ofblueberry acreage is treated with mesotrione. The low use ofmesotrione onthese minor crops 

### suggests that mesotrione is not critical for production of these crops. However, it cannotbe ruled out that mesotrione use on these minor crops may represent use for unique niche pests and/or crop conditions in 

### some production areas.
DATANEEDS 

### The Agency currently does not have importantinformation on 

### mesotrione. Obtaining the following information for the following registered agricultural sites: okra, oats, and flax which may improve future assessments conducted by the Agency related to the use and importance of mesotrione. Usage • Total pounds active ingredient applied • Percentcrop/site treated • Application rates: typical and

### maximum • Frequency ofapplication • Application Intervals • Methods ofapplication • Target or niche pests

Page9REFERENCES BEAD 2013. Mesotrione ((122990) Screening Level Usage Analysis. Biological and Economical Analysis Division. Office ofPesticide Programs, U.S. Environmental ProtectionAgency. Callisto•, Product Label. 2012. Syngenta. Syngenta Crop Production, LLC. Greensboro, North Carolina, NC 27419-8300. Available at: http://www.cdms.net/LDatlld56N005.odf. Accessed date, 

### Jan. 6 2014. Gregory, R. A., Hall, G. J., Wilson H. P., and N. Cullen. 2005. Mesotrione Plus Atrazine Mixtures for Control ofCanadaThistle. Weed Science: Vo1.53, No.2, pp. 202-211. Herbicide Handbook. 2007. 9th edition. Weed Science Society ofAmerica. Triclopyr. Pp 359- 361. 810 E. lOth Street, Lawrence, KS 66044-8897. Proprietary Data. 2001-2012. Richards, S. P., Buren, L. and L. Glasgow. 2002. Activity ofMesotrione onResistant Weeds in Maize. Pest Manag. Sci. 58(9):981-984. USEPA, 2001. Pesticide Fact Sheet- Mesotrione. Available at: http://www.e.pa.gov/oppOOOOl/chem search/reg actions/registrationlfs PC-122990 04- June-Ol.pdf. Accessed date, Dec. 24,2013. USEPA, 2010. Review onJustification for the Extension ofExclusive DataUse Period for Mesotrione (DP # 361356) Ratnayake, S. 2011. USEPA. Review onJustification for the Extension ofExclusive DataUse Period for Mesotrione (DP#389857) Walsh, M. J., Karrie. S., Kent, S., and S. B. Powles. 2012. Synergistic Effects ofAtrazine and Mesotrione on Susceptible andResistantWild Radish (Raphanus raphanistrum) Populations and the Potential for Overcoming Resistance to Atrazine Herbicides. Weedscience.org. 2014. International Survey ofHerbicide Resistant Weeds. Available at: httj?:l/www

.weedscience.org/summary/MOA.aspx. Accessed Date, Jan.8, 2014

. WSSA (Weed Science Society ofAmerica, Undated. Summary ofHerbicide Mechanism of Action. Weed Science Society ofAmerica. Available at: http://wssa.net/w.pcontent/uploads/WSSA-Mechanism-of-Action.pdf. Accessed Date, Jan. 6, 2014.

Page 10APPENDIXA
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 (inpounds) 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 pesticide used across agricultural land. The calculated values presented inthe map are not equivalentto an application rate (lb a.i./ A). The data usedto 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 onprivate market surveys ofpesticide use in agriculture averaged overthe 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 minorproduction 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 in the survey The result ofthese limitations is that states that show no usage may actually have a small amount ofthe active ingredientbeing used. In some cases the displayed use intensity may be distorted 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. It is important to note thatthe surveyed crops (about 60) are sampled from states that are majorproducers ofeach crop. Therefore, there are cases where the actual crop acreage in a state is higher than thatreported by crop acres grown in the survey because eitherthat 

### state and/or crop was not included inthe survey. The reader should pay particular attention to the figure legends and realize

.that a mapprepared for a particular chemical is not directly comparable to a map prepared for a different chemical as the legend bins will likely be different.

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