UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C

. 20460 

## JAN 09l014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION 

### MEMORANDUM SUBJECT:


### FROM:

THRU:

TO: 

### BEAD Chemical Profile (BCP) for Registration Review: Clopyralid Case (117401, 117403, 117404, and 117423) Sunil Ratnayake, Biologist

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### Biological Analysis Branch \__ V'V'-..'-' 

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# /r SepehrHaddad, Environmental Protection Specialist

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# ~~ Science Information and Analysis Branch

-

# f Stephen Smearman, Economist 

## J ,_**.,..k1u1~** Economic Analysis Branch

### ~'· Biological and Economic Analysis Division (7503P) Arnet Jones, Chief /)

# ~ _) Biological Analysis

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Diann Sims, Chief , 

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# f**~.**j,r..___. Science Information and Analysis ranch Timothy Kiely, Chief 

# a**~** Economic Analysis Branch Biological and Economic Analysis ivision (750 Steve Snyderman, Chemical Review Manager Pesticide Re-evaluation Division (7508P)



### Peer Review Panel date: October 23,2013SUMMARY Clopyralid was first registered as a pesticide in the U.S. in 1987 (US EPA, 1995). Clopyralid is a systemic herbicide belongs to the pyridine carboxylic acid family and it is applied as a postemergence herbicide to control broadleafweed species in many agricultural and non-agricultural use sites. The residential use ofthis herbicide is no longer approved. Clopyralid acts like a plant growth regulator 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) and the herbicides inthis group cause an uncontrolled cell devision leading to the death ofsusceptible plants. Clopyralid has a long period ofresidual activity and rotational interval for some crops is extended up to 18 months. Based onprivate market usage data from 1998-2012, usage averaged approximately 880,000 pounds active ingredient (a.i.) applied annually on approximately 10.5 million acres treated. The average a.i. rate over this time period was 0.084 pounds a.i./acre. Available non-agricultural usage data for clopyralid is limited and dated. The only reported 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 pest management roles and quantitative usage information for clopyralid. The BCP includes summaries ofprevious BEAD products and available public and/or private use and usage data for clopyralid to describe the role ofthis chemical in pest management. Additional information on use is available in the clopyralid PRD Label Data Report in the Public Docket. Informationprovided in this BCP may be used by stakeholders (e.g., users and registrants), OPP risk assessors, OPP risk managers, and the general public during the Registration Review process ofthispesticide. USE SITES Agricultural Use Sites Clopyralid registered agricultural use sites include: alfalfa, apples, almonds, asparagus, barley, beans, canola, chestnuts, cherries, cole crops, Conservation Reserve Program (CRP), com (field, pop, and sweet), cranberries, filberts, lentils, macadamianuts, mint, oats, pasture, rangeland, peas, peaches, pecans, pistachio nuts, potatoes, safflower, sorghum, soybeans, spinach, strawberries, sugarbeets, sunflower, wheat, and walnuts.

Page 2Non-agricultural Use Sites Clopyralid registered 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. FORMULATIONS 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 more than 20 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 SLUAtimeframe covers the years 2004-2012; however, during the mostrecent timeframe of2008-2012, the use on sugar beets has now dropped to only 10 percent ofcrop treated. Percent crop treated for alfalfa, apples, asparagus, celery, cherries, dry beans/peas, hazelnuts, oats, peaches, sorghum and sunflowers were all less than 1percent. 

## f\. search ofthe BEAD database for previous BEADproducts for clopyralid indicates that there 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 in registered use sites.

USAGE Agricultural Usage Based onprivate market usage data from 1998-2012, usage averaged approximately 880,000 pounds active ingredient (a.i.) applied annually on approximately 10.5 million acres treated. The average a.i. rate overthis time period was 0.084 pounds a.i./acre. Figure 1 presents clopyralid usage inpounds a.i

. over the 1998-2012 timeframe. Figure 2 presents total area treated in acres overthe same timeframe (Proprietary Data, 1998-2012).

Page 3199819992000200120022003200420052006200720082009201020112012 Years Source: Proprietary Data, 1998-2012


### FIGURE 2. Clopyralid Total Area Treated in Acres (1998-2012)

199819992000200120022003200420052006200720082009201020112012 Years Source: Proprietary Data, 1998-2012

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### Table 1. Comparison ofCropswith Highest Use ofClopyralid

- Percent ofTotal Lbs. Applied 2003-2007 

### and 2008-2012) 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, alfalfa, and cabbage. Other crops in the 2008-2012 timeframe include sugar beets, cabbage, sweet com, and sorghum. Source: Proprietary Data, 2003 -2012.


### Table2. Comparison ofStates with Highest Use ofClopyralid -Percent ofTotal 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 19% 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 in the 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: Proprietary Data, 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% over the same time period. Sugarbeets 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% ofthe total pounds for the 2008-2012 timeframe, an increase of3% compared to the 2003-2007 timeframe. The decrease in use on sugar beets is especially significant as use dropped from approximately 14 percent ofthe total pounds during the 2003-2007 timeframe comparedto approximately less than 3 percent oftotal pounds during the 2008-2012 timeframe.

Page 5North Dakota, Minnesota and Iowa were the top three states withthe highest use ofclopyralid in bothtime frames as shown in Table 2, with North Dakota (19%) having the highest percent of total pounds applied in both the 2003-2007 timeframe, and (34%) in the 2008-2012 timeframe. Usage has increased in North Dakota, while decreasing in Iowa, Minnesota and Wisconsin in the mostrecenttime frame of2008-2012. The average a.i. rate for the top crops interms ofpounds a.i. applied was the highest for pastureland at 0.196 lbs a.i./acre and the lowest for spring wheat at 0.074 lbs a.i./acre as shown in Table 3. Application Rates 

### T bl 3 Cl l"dU 

### T C A 

### AIR t 

### 2008 2012

a e 

# . opyra 1 

### se on op rops: verage 

# .. a e, 

# - Annual Average Annual Average Avg. A.I. Rate (lbs Crop Pounds Total Acres a.i./acres) Treated* Com 430,000 5,380,000 0.080 Wheat, Spring 317000 4,300,000 0.074 Barley_ 58,000 740,000 0.078 Wheat, Winter 47,200 570,000 0.083

Pastureland 25,600 130,000 0.196 *Total Acres Treated sums all acres treated for a crop, mcludmg those acres thatreceive multiple treatments. Source: Proprietary Data, 2008 -2012

Geographic Distribution of Clopyralid 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 inthe map are not equivalentto an applicationrate (lb ai/A). As shown in the map, North Dakota and NewJersey depict high use intensity ofacres treated with clopyralid inthose states. Please see Appendix I for further information onthe map.

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

Pounds Active Ingredient per 1.000 Crop Acres Grown CJNoData CJ <0.1 0

.1-1 1-3



### - 3-6



# - >6

Non-Agricultural Usage Available non-agricultural usage data for clopyralid is limited and dated. The only reported data available are for the years 2002, 2004, 2006 and 2012 for landscaping, lawn care operators, golf courses, institutional turf, nursery/greenhouses, and turffarms as shown inTable 4. Total nonagricultural 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 been recorded ina down use cycle.

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### Table

### 4. Clopyralid Non-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 

## * TurfFarms 13,500 50 900


### -



### TOTAL 103,660 191,500 34,455 NIA Source: ProprietaryData 2002, 2004, 2006, and 2012 • Proprietary data for 2012 reports usage ofclopyralid as a post emergentcontrol 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 orequal to 20,000 pounds ai. N/A indicates that the total number ofpounds applied in 2012 is not known.


### BIOLOGICALASPECTS RELEVANT TO CLOPYRALID Clopyralid is a selective systemic herbicide thatbelongs to the pyridine carboxylic acidfamily. 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, clopyralid belongs to the group ofsynthetic auxins (Group 4) (WSSA, 2013). These herbicides act like natural plant growthregulators by mimickingplant growth hormones. Clopyralid is absorbed by the plants through foliage and roots (ChemicalWatch Fact Sheet, 2013). Application ofherbicides belongingto group 4 causes uncontrolled cell devision leading to the death ofsusceptible plants. According to the available information, more than 50 broadleafweeds canbe controlled by application ofclopyralid (Stinger product label, 2010). To achieve a broader spectrum ofweed control clopyralid can be tank mixed with other synthetic plant growth regulators such as MCPA, 2,4-D, and triclopyr. Application rate ofclopyralid varies depending onthe type ofcrop (barley, canota, leafy vegetables, and field corn etc.), type ofweeds (annual, perennial), growth stage of the weed species, and the type ofland (cropping or fallow land). Ithas been reported that biotypes of9 weed species have developed resistance to clopyralid (International Survey of Herbicide Resistant Weeds, 2011). Clopyralid canpersist in soil for a long period depending onthe factors such as rainfall and organic matter content inthe soil (Stinger product 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 states (Stinger product label, 2010). Grass clippings from the pasture orhay fields sprayed with
Page 8clopyralid 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 commarigold 

### (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 postharvest treatment inthe field to control thistle, especially in sugarbeets 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 periodto avoid potential crop damage (Morishita, 2003). Withthe introduction ofRoundup Ready® sugar beets in 2008, growers are now able to have successive plantings ofsugarbeets withoutthe worry ofcrop damage that could occur when clopyralid is applied to fields betweenthe crops ofsugarbeets. This may be a factor contributedto the declining use ofclopyralid use in sugar beets seen onthe total number ofpounds used on sugar beets overthe time period 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 overthe last 10 years although the data are incomplete for the reporting year 2012. The overall picture for clopyralid use is mixed. Thetotal pounds ofactive ingredient applied (Figure 1.) overthe time period from 2000 to 2012 appears to be increasing after a period of decline as the total pounds applied in 2012 near the amounts applied in 2000. Inaddition 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 inuse onthese crops translates into large increases inthe percentages oftotal acres treated with clopyralid.

DATANEEDS The Agency currently does nothave important information onclopyralid. Obtainingthe following information may improve future assessments conducted bythe Agency related to the use and importance ofclopyralid. Informationneeded 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 each use site and how it is applied. Additional information is needed for the following uses: Agricultural Use Since BEAD proprietary databases do not contain survey data onregistered agricultural sites such as mint, lentils, and macadamianuts, andusage data for all sights such as the Page 9pounds a.i. applied, application method, percent ofthe crop treated and application rates would be beneficial.

Non Agricultural 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 inthe 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 in the 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 applicationrate (lb ai/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 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 thatproduce 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 ingredient being 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 onthe crops produced in the state.

Page 10The 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 importantto note that the 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 that reported by crop acres grown inthe survey because either that state and/or crop was not included inthe survey. The reader should payparticular 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 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/summary/MOASummary.asp Accessed onFeb. 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. USDA/ERS. Economic Information BulletinNumber 89. Proprietary Data. 1998-2012. (pesticide usage data)

Page 11Stingerproduct label. 2010. DowAgroSciences LLC. 9330 Zionsville Road, Indianapolis, IN 48268. US Census. 2012. Statistical Abstract ofthe United States 2012. Table 358 USDA. 2006-2010. NASS Crop Reporting Districts (shape file ofCRDs). Available at: http://www.ers.usda.gov/briefing/arms/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 Q uestions/county list.txt USDA. 2007. Census ofAgriculture. Online: http://www.agcensus.usda.gov/Publications/2007 /index.asp

. USDA, 2007. Census ofAgriculture. (for 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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