UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C. 20460 

# ocro 1 2014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM SUBJECT:

FROM:

THRU: BEAD Chemical Profile (BCP) for Registration Review: Clopyralid Case (117401, 117403, 117404, and 117423) Sunil Ratnayake, Biologist /"\.

. \--; 

# St__ Biological Analysis Branch 

# L V\\l...cJ \ Sepehr Haddad, Environmental Protection Specialist 

# Jfls**~** Science Information and Analysis Branch Stephen Smearman, Economist }..J._

## -l,Jt-11~ Economic

### Analy~is Branch

### ~ Biological and Economic Analysis Division (7503P)

Timothy Kiely, Chief

## ~**~** Economic Analysis Branch 

## 1!\fl Biological and Economic Analy s Divisi n 503P) TO: Steve Snyderman, Chemical Review Manager Pesticide Re-evaluation Division (7508P)

Peer Review Panel date: October23, 2013

### SUMMARY Clopyralid was first registered as a pesticide in the U.S. in 1987 (US EPA, 1995). Clopyralid is a systemic herbicide that belongs to the pyridine carboxylic acid family. It is applied as a postemergence herbicide to control broadleafweed species in many agricultural and non-agricultural use sites. Itis no longer registered for residential use. Clopyralid acts like a plant-growth regulator (PGR) by mimicking natural plant growth hormones (auxins). According to the Weed Science Society ofAmerica (WSSA) mechanism ofaction ofherbicides, clopyralid belongs to the Group 4 herbicides (synthetic auxins). The herbicides in this group cause uncontrolled cell devision leading to the death ofsusceptible plants. Clopyralidhas a long period ofresidual activity and the rotational interval for some crops is extended up to 18 months. Based onprivate marketusage data from 1998-2012, usage averaged·approximately 880,000 pounds acid equivalent (a.e.) applied annually on approximately 10.5 million acres treated. The average a.e. rate over this time period was 0.084 pounds a.e./acre. Available non-agricultural usage data for clopyralid is limited and dated. The onlyreported data available are for the years 2002, 2004 and 2006 for landscaping, lawn care operators, golfcourses, institutional turf, nursery/greenhouses, and turffarms. 

### INTRODUCTION The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pestmanagementroles and quantitative usage information for clopyralid. The BCP includes summaries ofprevious BEAD products and available public and/or private use and usage data for clopyralidto describe the role ofthis chemical in pest management. Additional information on use is available in the clopyralid PRD Label DataReport in the Public Docket. Information provided in this BCP maybe usedby stakeholders (e.g., users and registrants), OPP risk assessors, OPP risk managers, and the general public during the Registration Reviewprocess ofthis pesticide. 

### USE SITES Agricultural Use Sites Clopyralidregistered agricultural use sites include: apples, asparagus, barley, canola, cherries, cole crops, Conservation Reserve Program (CRP), com (field, pop, and sweet), cranberries, mint, oats, pasture, rangeland, peaches, spinach, strawberries, sugar beets, and wheat. Non-agricultural Use Sites Clopyralidregistered non-agricultural use sites include: cemeteries, farm buildings, fencerows, industrial sites, ornamental lawns and turf, ornamentals trees, athletic fields, golffairways, parks, and rights-of-way. ·

Page2FORMULATIONS AND APPLICATION METHODS Clopyralid formulations include emulsifiable concentrate, soluble concentrate, solution-ready to use, wettable powder and water dispersible granules. Application methods include aerial and ground.

HISTORY OF CLOPYRALID AND BEAD PRODUCTS Clopyralid is a systemic herbicide registered for use in the U.S. since 1987. A Screening Level Usage Analysis (SLUA) (BEAD, 2013) provides percent crop treated for crops for which usage data was available. The agricultural sites withthe greatest number ofpounds used were for wheat and com. In terms ofthe percent crop treated, sugar beets averaged 45 percent crop treated followed by barley with 15 percent crop treated, and cabbage with 10 percent crop treated. It should be noted that the SLUA timeframe covers the years 2004-2012; however, during the most recent timeframe of2008-2012, the use on sugar beets has nowdropped to only 10 percent ofcrop treated. Percent crop treated for apples, asparagus and peaches were all less than 1percent. A search ofthe BEAD database for previous BEAD products for clopyralid indicates thatthere are no records ofprior BEAD benefits assessments or Section 18s requests for clopyralid. However, a lack ofSection 18 requests assessments does not specifically indicate the relative importance ofthe chemical inregistered use sites.

USAGE Agricultural Usage Based onprivate market usage data from 1998-2012, usage averaged approximately 880,000 pounds active ingredient (a.e.) applied annually on approximately 10.5 million acres treated. The average a.e. rate overthis time period was 0.084 pounds a.e./acre. Figure 1presents clopyralid usage inpounds a.e. over the 1998-2012 timeframe. Figure 2 presents total area treated in acres overthe same timeframe (Proprietary Data, 1998-2012).

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### FIGURE 1. 

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199819992000200120022003200420052006200720082009201020112012 Years
Source: ProprietaryData, 1998-2012


### FIGURE 2. Clo ralid TotalArea Treated in Acres 1998-2012

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## ... u <( .5 "D Ill 1ii Ill 

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## "' Ill 

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199819992000200120022003200420052006200720082009201020112012 Years Source: Proprietary Data, 1998-2012



### Page4Table 

### 1. Comparison ofCrops with HighestUse ofClopyralid

- Percent ofTotal Lbs. Applied 2003-2007 and 2008-20121 2003-2007 2008-2012 Average annual= 763,000 lbs/yr Average annual= 900,000 lbs/yr Crop %Lbs Crop %Lbs Com 58% Com 48% Wheat, Spring 17% Wheat, Spring 35%

Sugar Beets 14% Barley 6% Pasture/Rangeland 7% Wheat,Winter 5% Barley 3% Pasture/Rangeland 3% Other* 1% Other* 3% *Other crops in the 2003-2007 timeframe include canola, winter wheat, and cabbage. Other crops in the 2008- 2012 timeframe include sugarbeets, cabbage, and sweet com. Source: Proprietary Data, 2003 -2012.

Table 2. Comparison ofStates with Highest Use ofClopyralid- PercentofTotal Lbs. Applied (2003-2007 and 2008-2012) 2003-2007 2008-2012 Average annual= 763,000 lbs/yr Average annual=900,000 lbs/yr State %Lbs State %Lbs North Dakota !"9% North Dakota 34%

Minnesota 17% Minnesota 12% Iowa 13% Iowa 11% Wisconsin 10% Nebraska 6%

Illinois 7% Indiana 6% Nebraska 6% Illinois 5%

Other* 28% Other* 26% *Other States inthe 2003-2007 timeframe include Michigan, Texas, Indiana, Idaho, South Dakota and Ohio. Other States in the 2008-2012 timeframe include Wisconsin, South Dakota, Idaho, Michigan, Montana and Texas. Source: ProprietaryData, 2003 -2012 As shown in Table 1, in terms ofclopyralid's use distribution ofthe total pounds applied to all registered agricultural crops, the major agricultural use ofclopyralid for the 2003-2007 and 2008-2012 time frames is on com (58% oftotal pounds applied in 2003-2007 and while still the leading use site, declining to 48% ofthe total pounds applied in 2008-2012). This is followed by spring wheat which increased from 17% to 35% overthe same time period. Sugar beets accounted for 14% ofthe total pounds for the time period 2003-2007 has declined significantly dropping to less than 3% ofthe total pounds applied. Barley accounted for 6% ofthetotal pounds for the 2008-2012 timeframe, an increase of3% comparedto the 2003-2007 timeframe. The decrease inuse on sugar beets is especially significant as use dropped from approximately 14 percent ofthe total pounds during the 2003-2007 timeframe compared to approximately less than 3 percent oftotal pounds during the 2008-2012 timeframe. NorthDakota, Minnesota and Iowa were the top three states with the highest use ofclopyralid in bothtime frames as shown in Table 2, withNorth Dakota (19%) having the highest percent of Page 5total pounds applied inboththe 2003-2007 timeframe, and (34%) inthe 2008-2012 timeframe. Usage has increased inNorth Dakota, while decreasing in Iowa, Minnesota and Wisconsin inthe most recent time frame of2008-2012. The average a.e. rate for the top crops interms ofpounds a.e. applied was the highest for pastureland at 0.196lbs a.e./acre and the lowest for spring wheat at 0.074lbs a.e./acre as shown inTable 3. Application Rates 

### Table 3. Clopyralid Use on Top Crops: Average A.E. Rate, 2008-2012 Crop
Com Wheat, Spring Barle)'_ Wheat, Winter

Pastureland 

### AnnualAverage Pounds 430,000 317000 58,000 47,200 25,600 

### AnnualAverage TotalAcres

Treated* 5,380,000 4,300,000

740,000 570,000 130,000 

### A vg. A.E. Rate (lbs a.e./acres) 0.080 0.074 0.078 0.083 0.196 *Total Acres Treated sums all acres treated for a crop, mcludmg those acres thatrece1ve multiple treatments. Source: Proprietary Data, 2008 -2012

Geographic Distribution ofClopvralid Use Figure 3 provides a very broad geographical view ofthe average annual amount (in pounds) of clopyralid applied per 1,000 acres ofcrop acres grown. These data are included inthe maps because risk assessors are interested inthe amount ofa pesticide used across agricultural land. The calculated values presented-in the map are not equivalent to an application rate (lb ae/A). As shown inthe map, North Dakota and NewJersey depict high use intensity ofacres treated with clopyralid inthose states. Please see Appendix I for further information on the map.

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### FIGURE 3. AnnualAverage AgriculturalUse Intensity ofClopyralid (2008-2012).

Pounds Acid Equivalent Per 1,000 Crop Acres Grown 

### 0 No Data 0 <0

.1 o o .1-1 1-3 3-6



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Non-Agricultural Usage Available·non-agricultural usage data for clopyralid is limited and dated. The only reported data for non-agricultural usage and which is available in terms ofactive ingredient (a.i.) are for the years 2002, 2004, 2006 and 2012 for landscaping, lawn care operators, golfcourses, institutional turf, nursery/greenhouses, and turffarms as shown in Table 4. Total non-agricultural usage between 2006 and 2012 appears to have declined significantly. However, there is a gap inthe data for the years between 2006 and 2012 and more recent data (data for the years between 2006 and 2012) is not complete and are not available to determine ifthis is a trend as it appears to be or a fluctuation in use that has beenrecorded in a down use cycle.

Page7Table 4. ClopyralidNon-A2riculturalUsa2e (Pounds A.I. (2002-2012) Site 2002 2004 2006 2012 GolfCourses 8,250 35,900 11,800 15,000 Institutional Turf 11,250 2,300 4,700 

## * Landscape 5,700 133,400 5,900 

## - Lawn Care Operators 64,600 18,700 11,150 

## * Nursery/Greenhouse 360 1,150 5 

## * TurfFanns 13,500 50 900


### -

TOTAL 103,660 191,500 34,455 N/A Source: ProprietaryData 2002, 2004, 2006, and 2012 • Proprietary data for 2012 reports usage ofclopyralid as a post emergent control used in coformulated products. However, it is not possible to disaggregate the number ofpounds a.i. from the estimate provided. A dash ( - ) indicates that there is no reported usage. Itis estimated thatthe total usage is less than or equal to 20,000 pounds ai. N/ A indicates that the total number ofpounds applied in 2012 is not known.

BIOLOGICAL ASPECTS RELEVANT TO CLOPYRALID Clopyralid is a selective systemic herbicide that belongs to the pyridine carboxylic acid family. Aminopyralid, fluroxypyr, and triclopyr are the other herbicides that belong to the pyridine carboxylic acid family. Clopyralid can be applied as a post-emergence herbicide to control broadleafweed species in many agricultural and non-agricultural use sites and there are no residential uses ofthis herbicide. According to the Weed Science Society ofAmerica (WSSA) mechanism ofaction classification, clopyralidbelongs to the group ofsynthetic auxins (Group 4) (WSSA, 2013). These herbicides act like natural plant growth regulators by mimicking plant growth hormones. Clopyralid is absorbed by the plants through foliage and roots**(Che~icalWatch** Fact Sheet, 2013). Application ofherbicides belonging to group 4 causes uncontrolled cell devision leading to the death ofsusceptible plants. According to the available information, more than 50 broadleafweeds can be controlled by application ofclopyralid (Stinger productlabel, 2010). To achieve a broader spectrum ofweed control, clopyralid canbe tank mixed with other synthetic plant growth regulators such as MCPA, 2,4-D, and triclopyr. Applicationrate ofclopyralid varies depending onthe type ofcrop (barley, canola, leafy vegetables, and field cometc.), type ofweeds (annual, perennial), growth stage ofthe weed species, and the type ofland (cropping or fallow land. According to the International Survey ofHerbicide Resistant Weeds, biotypes of8 weed species have developed resistance to the mode ofactionofGroup 4 herbicides inthe United States. However, no reports could be found onthe development ofweed resistance, specifically to clopyralid in the United States (International Survey ofHerbicide

.Resistant Weeds, 2013). Clopyralid canpersist in soil for a long period depending onthe factors such as rainfall and organic matter content in the soil (Stingerproduct label, 2010). Due to this long period of residual activity, the rotational interval for some crops such as cotton, sunflower, potato, lentils, and peas is extended up to 18 months depending onthe soil and weather conditions ofdifferent Page 8states (Stingerproduct label, 2010). Grass clippings from the pasture orhay fields sprayed with clopyralid can contaminate the compost and the use ofcontaminated compost with clopyralid has resulted in crop injuries even a year after the initial application (Miltner et al., 2003). ROLE OF CLOPYRALID IN PEST MANAGEMENT Clopyralid is an herbicide widely used to control commonbroadleafweeds including invasive and noxious weeds on agricultural as well as non-agricultural areas (Clopyralid Fact Sheet, 2013). Clopyralid is registered for the control ofa variety ofannual and perennial broadleaf weeds, including corn marigold (Chrysanthemum segetum) and especially the invasive weed creeping thistle (Cirsium spp.), in established grassland, non-crop land and ornamentals (Herbicide Handbook, 2003). Clopyralid has a niche use inthat and it is used as a post harvest treatment inthe field to control thistle, especially in sugar beets and small grains. However, because clopyralid canpersist inthe soil, some sensitive crops to clopyralid such as dry beans, sunflower, peas, and potatoes, have a long rotational period to avoid potential crop damage (Morishita, 2003). Withthe introduction ofRoundup Ready® sugar beets in 2008, growers are now able to have successive plantings ofother crops without the worry ofcrop damage that could occur due to the residual activity ofclopyralid

. The increased use ofgylphosate may be a factor contributed to the declining use ofclopyralid in sugarbeets from 2008-2012.
In addition, clopyralid can also be used for turfand golfcourse management and by landscape, nursery/greenhouse and lawn care operators. Based onthe timeframe from 2002 to 2006 it appears that use on non-agricultural sites has significantly declined over the last 10 years although the data are incomplete for the reporting year 2012. The overall picture for clopyralid use is mixed. The total pounds ofactive ingredient applied (Figure 1.) over the timeperiod from 2000 to 2012 appears to be increasing after a period of decline as the total pounds applied in 2012 nearthe amounts applied in 2000. Ill addition the overall number ofacres treated has increased over the last five years indicating that clopyralid has found niche uses in field crops such as barley and spring and winter wheat. These are major field crops with large numbers ofacres grown so small percentage increases in use onthese crops translates into large increases inthe percentages oftotal acres treated with clopyralid.

DATA NEEDS The Agency currently does not have important information on clopyralid. Obtainingthe following information may improve future assessments conducted by the Agency related to the use and importance ofclopyralid. Information needed includes why after years ofdecline is clopyralid use increasing especially for particular crops, how is itbeing used, howmuchis used, what is the typical rate for eachuse site and how it is applied. Additional informationis needed for the following uses:

Page 9Agricultural Use Since BEAD proprietary databases do not contain survey data onregistered agricultural sites such as mint, lentils, and macadamianuts, and usage data for all sights such as the pounds a.e. applied, application method, percent ofthe crop treated and application rates would be beneficial.

NonAgricultural Use BEAD has very limited recent (post-2006) usage data except for available data from 2012 for golfcourses. Information needed includes the pounds a.i. applied, application rates, application method and percent crop treated for the following: institutional turf, landscaping, nursery/greenhouses, and turffarms.
APPENDIX I. 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 pesticide used across agricultural land. The calculated values presented in the map are not equivalent to an application rate (lb ae/ A). The data used to make these maps have several limitations. Any interpretation ofthe maps should considerthe underlying data andthe associated limitations carefully. The numerator (annual average pounds applied) is based onprivate 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 in the survey The result ofthese limitations is that states that showno 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 maynot accurately represent the actual pesticide usage onthe 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
Page 10a state is higher than that reported by crop acres grown in the survey because either that state and/or crop was not included inthe survey. The reader should payparticular attention to the figure legends andrealize that a map prepared for a particular chemical is not directly comparable to a map prepared for a different chemical as the legend bins will likely be different.

REFERENCES BEAD, 2013. Clopyralid Screening Level Usage Analysis. Biological and Economic Analysis Division, Office ofPesticide Programs, US Environmental Protection Agency. March 19. Britt, C., A. Mole, F. Kirkham and A. Terry. 2003. Herbicide Handbook, Guidance onthe use of herbicides onnature conservation sites. Publication ofEnglishNature. PO Box 1995, Wetherby, West Yorkshire LS 23 7XX. http://www.naturalengland.org.uk/

. Access on Oct. 25, 2013. Clopyralid. 2013. Chemical Watch Fact Sheet. On line Publication. http://www.beyondpesticides.org/pesticides/factsheets/clopyralid.pdf

. Accessed on Oct. 29,2013. International Survey ofHerbicide Resistant Weeds

. 2013. http://www.weedscience.org/surrunary/MOASummary.asp Accessed on Feb. 25, 2013. Proprietary Data, 2002, 2004, 2006 and 2012. (non-agricultural usage data) Miltner, E., et al. 2003. Clopyralid and Compost: Formulation and Mowing Effects on Herbicide Content ofGrass Clippings. Compost Science & Utilization. 11(4): p. 289-299. Morishita, D. W. 2003. Herbicides for Weed Control in Sugar Beets. http://www.uiweb.uidaho.edu/sugarbeet /weed/Herbicides%20for%20sugar%20beets.pdf Accessed on Dec.19, 2013. Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses ofLand in the United States, 2007. USDAIERS. Economic Information BulletinNumber 89. Proprietary Data. 1998-2012. (pesticide usage data) Stingerproduct label. 2010. DowAgroSciences LLC. 9330 Zionsville Road, Indianapolis, IN 48268. US Census. 2012. Statistical Abstract ofthe United States 2012. Table 358.

Page 11USDA. 2006-2010. NASS Crop Reporting Districts (shape file ofCRDs). Available at: http://www.ers.usda.gov/briefing/anns/resourceregions/resourceregions.htm#nass

. USDA. 2006-2010. NASS Crop Reporting Districts. Online: http://www.nass.usda.gov/Data and Statistics/County Data Files/Frequently Asked 

### 0 uestions/county list.txt USDA. 2007. Census ofAgriculture. Online: http://www.agcensus.usda.gov/Publications/2007/index.asp

. USDA, 2007. Census ofAgriculture. Land in Farms data). Available at: http://www.agcensus.usda.gov/Publications/2007/index.asp

. WSSA. 2013. Summary ofHerbicide Mechanism ofAction According to the Weed Science Society ofAmerica (WSSA). http://wssa.net/wp-content/uploads/WSSA-Mechanism-of-Action.pdf

. Accessed on Feb. 25, 2013.

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