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## MAR 21 2014 OFFICE OF CHEMICAL SAFETY A N D POLLUT I O N PREVENT I O N MEMORANDUM
SUBJECT:

FROM:

THRU: BEAD Chemical Profile (BCP) for Registration Review: Aminopyralid Case Level Composed of Aminopyralid (0051 00), Aminopyralid, Potassium Salt (005219) and Triisopropanolamine Salt of Aminopyralid (005209)

# S~nil**~atnayake, ~iologist**  

# r-l

.**~** £ Biological Analysis Branch \._, '"'-A....**"'-~1tA../"""---** Rafael A. Prieto, Environmental Protection

# Special~st**,J 7/** 

# h-t-J 

# 1:**-f?vjJ{o** Science Information and Analysis Branch ·. · 

# f t-
- S tephen Smearman, Economis t Economic Analysis Branch

# ~ Biological and Economic Analxsis Division (7503P) Arnet Jones, Chief Biological Analy s i s Br Diann Sims, Chief Science Information and Analysis Branch Timothy Kiely, Chief

# /l10t~W~**I~** Economic Analysis Branch Biological and Economic Analysis Division (7503P) TO: Veronica Dutch, Chemical Review Manager Risk Management and Implementation Branch 5 Pesticide Re-evaluation Division (7508P)


### Peer Review Panel date: March 19, 2013SUMMARY Aminopyrali d was registered in the U.S. in 2005 and is a systemic herbicide used for the control of broadleaf weeds in forage and grass crops and agricultural and non- agricultural lands. Registered agricultural use sites for this case include corn (silage/field), wheat, hay and pasture crops and forest p l an t ings. It is also used on fallow and on Conservation Reserve Program (CRP) lands. The registered non-agricultural use sites include airports/landing fields, industrial and construction areas. Aminopyralid controls many annual, biennial, and perennia l broadleaf weeds in pasture lands including invasive weed species (SDSU, 2013). More than 98 percent of aminopyralid's reported use is on pasture, with about 40 percent of this use reported for Texas
.. Aminopyralid is an important component of integrated vegetation management programs to renovate or restore desired p lant communities. It has long residual activity which can reduce weed re-infestation and the need for re-treatment. Depending on the environmental conditions, an interval of at least two years is required before re -planting of a broadleaf crop. Aminopyralid belongs to the pyridine carboxylic acid family. It can be applied as pre-emergence or post
- emergence treatments using aerial and ground application methods
. According to the Weed Science Society of America (WSSA) classification of herbicides, aminopyralid belongs to Group 4 (synthetic auxins). Group 4 herbicides mimic natural plant growth hormones (auxins) and cause uncontrolled cell dev i sion which leads to the death of susceptible plants. INTRODUCTION The Biological and Economic Analys i s Division (BEAD) Chemica l Profile (BCP) provides an overview of the pest management roles and quantitative usage information for aminopyrali d. The BCP includes summaries of previous BEAD products and available pub lic and/or private use and usage data for aminopyralid to describe the role of this chemical in pest management. Additional information on use is available in the aminopyralid PRD Label Da ta Report
. 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 of this pesticide. Aminopyralid was registered in the U.S. in 2005 (EPA, 2013)
. Thi s pesticide belongs to the pyridine carboxylic acid family and used as a pre-emergence as well as a post-emergence herbicide to control broadleafweed species in many agricultural and non-agricultural use sites described below. It is a systemic herbicide which provides a broad-spectrum contro l of number of noxious and invasive annual , biennial and perennial weed species. Depending on app lication rate and target weeds, arninopyralid provides res idual control which helps avoid weed reinfestations and minimizes the need for re - treatment.

Page 2USE SITES Registered agricultural use sites for aminopyralid include wheat, hay and pasture crops. Registered use sites for aminopyralid potassium salt are forestry plantings, wheat, hay, and pasture crops . It is a l so used on Conservation Reserve Program (CRP) lands, rights-of

- way, fallow and non-agricultural uncultivated areas including seasonally flooded wetland areas when dry
. Registered use sites for aminopyralid triisopropano lamine salt include forestry plantings , wheat, corn (field/silage), hay and pasture crops. Its other uses include CRP areas, airports/landing fields, industrial and construction areas , fallo w and non -agricultural uncultivated areas, including seasonally flooded wetland areas when dry. FORMULATIONS AND APPLICATION METHODS Aminopyralid is form ulated as an emul sifiab le concentrate . Aminopyralid potassium salt is formulated as a dry flowable and emulsifiable concentrate . Aminopyralid triisop ropanolamine salt is formulated as · emul sifiable concentrate, li quid soluble concentrate, and flowable concentrate. Aminopyralid can be applied pre-emergence or post-emergence using aerial and ground application meth ods
. HISTORY OF AMINOPYRALID and BEAD PRODUCTS Aminopyralid is a selective sys temic herbicide registered for use in the U.S. in 2005 for control of certain woody plants and broadl eaf weeds such as thistles. A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 201 4 that provides percent crop treated for fallow, winter and spring wheat and pastureland for whi ch usage data was available. The highest number of pounds of acid equivalent used over the SLUA timeframe (2004-2012) was on pastureland which accounted for over 98 percent ofthe aminopyralid usage, which accounts fo r approximately 2.5 percent crop treated for pas tureland. This was followed by winter wheat and spring wheat with approx imately one half of one percent each of the usage. The relatively low percent crop treated for pasture land may not be an indication of a lack of overall benefit to growers as pasture is a very low input site. There are no records of prior BEAD assessments relevant to the benefits of aminopyrali d. USAGE Usage Trends Use in terms of both pounds a. e. and total area treated increased steadily following this chemical's reg i stration in 2005, leveling out after 2009 (Proprietary data, 2006-2012). Since 2009 , aminopyralid annual agricultural usage averaged 142,000 pounds a.e. treating an average of 2.1 milli on acres, for an overall average application rate of 0.07 pounds a.e. per acre . Page 3Figure 1 presents ami nopyralid's usage in pounds a.e. over the 2006-2012 time f rame. F igure 2 presents total area treated in acres over the same timeframe. 

### Fi ure 1. 

### Amino ralid Total Pounds A.E. 2006-2012 1 80 , 000

2006 2007 2008 2009 2010 2011 2012 Year
Source: Proprietary Data, 2006-2012. 

### Fi ure 2. Amino ralid T otal Area Treated in Acres

2, 500,000

2006 2007 2008 2009 2010 2011 2012 Year Source: Proprietary Data, 2006

- 2012
. As shown in T able 1> pastureland is the highest use site for aminopyralid, both in terms of pounds a. e. and in total area treated. More than 98 percent of aminopyral id ' s use i s on pastureland, with about 40 percent of the use aminopyralid in Texas as shown in T able 2. T he highest average application rate is on pasture land wi th 0.07lb a.e ./ acre as shown in T ab le 3.

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### Table 1. 

### Crops with Highest Use of Aminopyralid- Percentage of Total Lbs
. A
. E
. Applied on Pastureland
. 2006-2012 

### Crop %LB Pas t ureland 98.7 Source: Proprietary Data, 2006

- 2012 

### Table 2
. States with Highest Use of Aminopyralid-% of Total L bs. Applied (2006

-2012) 2006-2012 State %Lbs Texas 42 Oklahoma 

### 6

Georgia 5.2 Minnesota 5.1

V irgini a 5 Source: Proprietary Data , 2006-2012. 

### Application Rates T 

### b l 3 A

. 

## rd u

a e 

# . mmopyra 1 

### se on 

## c rops: A**vera~e** 

### AE R 

# . . ate, 2006 2012 p 

# - on I d 

### asture an Crop Average Pounds Average T otal Acres Avg
. AI Rate Treated* (lbs a.e.lacres) Pastureland 92,000 1, 307,000 0.069 *Total Acres Treated sums all acre s treated for a crop, mcludmg those acres that receive mul t iple treatments. Source: EPA Proprietary Data , 2006

- 2012

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### Geographic Distribution of Aminopyralid Use Another measure of usage is the use intensity. In this analysis, the use intensity is expressed as the average annual amount (in pounds) ofthe acid equivalent applied per 1,000 acres of crop acres grown, including pasture. This differs from the application rate, which i s expressed as the pounds a.e. applied per treated area. Figure 3 spatially represents propargite use intensity in the U.S. Use is widespread, but at very low le vel; in most states, use is less than one pound a.e. per 1 , 000 acres in crops. Use is relative ly more intense in areas ofthe southeast, from Texas through Georgia and South Carolina. Compared to western states , where lives tock are grazed extensively, pastures in the southeast are more intensively managed.

Pounds Acid Equivalent Per 1,000 Crop Acres Grown 

### D No Data c:J < 0
. 1

. 0
. 1 · 0
. 5

. 0.5 · 1 

# - > 1

Figure 3
. Annual Average Agricultural Use Intensity of Aminopyralid (2008-2012). (Source: Proprietary Da ta) For more information about the methodology used to create this map , see Appendix A. 

### Non-Agricultural Usage No usage data is available for non- agricultural uses of these chemicals. There is some indication that there is use for industrial and institutional vegetation management, but BEAD does not have any usage data available for th ese sites. Page 6BIOLOGICAL ASPECTS RELEVANT TO AMINOPYRALID Aminopyralid is a selective systemic herbicide used for the control of broadleaf weeds in many agricultural and non-agricultural sites. It can provide broad-spectrum control of number of noxious and invasive annual, biennial and perennial weed species. Aminopyralid can be applied as post-emergence treatments to control the emerged weeds and pre-emergence treatments to control germinating seeds or emerging seedlings of susceptible broadleaf weeds
. Aminopyralid is absorbed by the plants through foliage and roots and translocated throughout the plant (Herbicide Handbook, 2007). According to the Weed Science Society of America (WSSA) mechanism of action ofherbicides, aminopyralid belongs to the Group 4 herbicides (synthetic auxins)
. Herbicides in this group acts like a plant growth regulator by mimicking natural plant growth hormones (auxins) and cause uncontrolled cell devision leading to the death of susceptible plants (WSSA, Undated). Herbicide injuries to non-target broadleafplants have been reported due to the use of compost, manure, or urine from animals consuming grass or hay treated with this pesticide. ROLE OF AMINOPYRALID IN PEST MANAGEMENT Aminopyralid is a herbicide used to manage broadleaf weeds including invasive and noxious weeds on rangeland, grass pastures, conservation reserve lands, and non- crop land areas such as roadsides, non - irrigation ditch banks, recreation areas, and campgrounds (USEPA, 2005; SDSU, 2010, SDSU, 2013). Aminopyralid is an important component of integrated vegetation management programs to renovate or restore desired plant communities. More than 98 percent of aminopyralid use is for weed control in pasturelands (Table 1). Aminopyralid controls many annual, biennial, and perennial broadleaf weeds in pasturelands including invasive weed species (SDSU, 2013). Canada thistle (Cirsium arvense), perennial showthistle (Sonchus arvensis), tansy ragwort (Seneciojacobaea), absinth wormwood (Artemisia absinthium) , Russian knapweed (Acroptilon repens), spotted knapweed (Centaurea stoebe) are some of the weed species that can be controlled by applications of aminopyralid in pasturelands (SDSU, 2013)
. In wheat, aminopyralid can be applied for control of key broadleaf weeds, including wild buckwheat (Polygonum convolvulus), prostrate knotweed (Polygonum aviculare), milk thistle (Silybum marianum), and com marigold (Chrysanthemum segetum) (Herbicide Hand Book, 2007)
. Aminopyralid can provide long residual weed control of some of these weeds such as knap weeds (Centaurea diffusa) and thistle species (Cirsium arvense; Carduus nutans) (BASF, 2012; Endres & Kline, 2011). Use ofaminopyralid can avoid weed re-infestations and minimize the need for re-applications
. This is a particular benefit for use in pasture, but can complicate crop rotations between grain crops and crops such as beans and oilseeds. The spectrum of weeds controlled by aminopyralid can be maximized by 

### tank mixing aminopyralid with other herbicides such as 2, 4 -D , and triclopyr (SDSU, 201 0; Dow Agro Sciences, Undated). According to the International Survey of Herbicide Resistant Weeds, biotypes of eight weed species have developed resistance to the Group 4 herbicides. However, weed resistance specifically to aminopyralid has not been reported (Heap, Undated). Page 7DATA NEEDS The Agency currently does not have important information on aminopyralid. Obtaining the following information may improve future assessments conducted by the Agency related to the use and importance of aminopyralid. Data on aquatic uses (usage on sites that may be seasonally flooded or tidal. Wetlands, marshes, swamps, bogs, river and stream channel s etc.). Agricultural Use BEAD proprietary databases contains some survey data on registered agricultural sites such as wheat, hay, and pasture but quantifiable usage data such as pounds a.e. applied and application rate information would be useful if availab le
. BEAD does not have detailed agricultural u sage information on sites such as rangeland
. Usage data such as pounds a.e. app lied and application rates woul d be useful for all sites tha t have tolerances. Non Agricu ltural Use BEAD does not have detailed non-agricultural usage on the following s ites: rangeland, conserva tio n reserve lands, and non-crop land areas such as roadsides, non - irrigation ditch banks, recreation areas, and campgrounds
. Usage data such as pounds a.e. applied and application rates would be useful if available. BEAD needs actual usage data so that we can improve our assessments. REFERENCES BASF. 2012. Invasive Plant Management with Mi le stone® and Other Herbicides. Guide for Natural Area Managers. 20 I2
. Online Publication. Available at: http: // rnsdssearch.dow.com/PublishedLiteratureDAS/dh 0898/0901 b803808981 dd.pdf?fi lepath=ivm/pdfs/noreg/0 I 0

- 50904
.pdf&fromPage = GetDoc
. Accessed on Ma rch II, 20I4. Dow Agro Sciences. Undated. Range and Pasture. Online Publication. Availa ble at: http: //www.dowagro.com /range/resource/milestone faq.htrn#faq4
. Accessed on March18, 2014
. Endres, G, and E. Kline. 20II. Perennial Weed Contro l with Aminopyralid and Aminocyclopyrachlor, Sheridan Cou nty . Publication of North Dako ta State Uni versi ty. Online Publicat ion. Availab le at: http: //www .ag.ndsu.edu/carringtonREC /documents/ agronornyrd/docs20 1112011 %20Pere nnial%20Weed%20Control%20with%20Arninopyralid%20and%20Aminocyclopyrachlor -%20Sheridan%20County.pdf /view
. Accessed on March 11,2014. Heap, 

### I. (Undated)
. The Internatio nal Survey of Herb icide Resistant Weeds. Online Publication. Available at: www.weedscience.org. Accessed on Feb 12, 20 14. Page 8Herb icide Handbook. 2007
. 9 1h edition
. Weed Science Society of America. Aminopyralid. Pp 331-332. 810 E. 10 ih Street, Lawrence, KS 66044-8897
. Proprietary Data. 2006-2011. (pesticide usage data). South Dakota S tate University (SDS U). 2010. Pasture and Range. Online Pub lication. Available at: http: //www .sdstate.edu/ps/extension/weed-mgmt/upload/FS525P .pdf. Accessed on March 18 , 2014. South Dakota State Uni versity (SDSU). 2013
. Pasture and Range. Online Publication. Availab le at : https: / /www .google.com/search?g = 20 13+weed+control+ SDS U+extens ion+ south+dakota &rls=com
.microsoft%3Aen-us%3AIE-SearchBox&oe=UTF8&rlz= 117RNTN enU S323&safe=on&hl=en&sa =X&as q = &nfpr=& s pell= 1 &ei=H Qq U5HFL4

- wOAG7gYHwA Q&v ed= OCBg0vwU Accessed on March 18,2014. United States Environmental Protection Agency (USEPA)
. 2005. Pesticide Fac t Sheet. Aminopyralid. http: //www .epa.gov/oppOOOO 1 /chem search/reg actions/registration/f s PC-0051 00 1OAug-05.pdf
. Accessed on Aug
. 28, 2013. USEPA, 2013
. OPPIN database. Weed Science Society of America (WSSA). Undated. Summary of Herbicide Mechanism of Action. Online Pub li cation. Available at: http ://wssa .net /wp-content/uploads/WSSA-Mechanism-of-Action.pdf. Accessed on Aug. 28,2013.

Page9APPENDIX A The map included herein is primarily for the use of the risk assessors in t he Environmental Fate and Effects Division. The map provides a very broad geographical view of the amount (in pounds) of the acid equivalent applied pe r 1,000 acres of " land in farms". These data are included in the maps because risk assessors are interested in the amount of a pesticide used across farmland. Because ofthe definition of Land in Farms , as discussed below, the calculated values presented in the map are not equivalent to an application rate (lbs a.i/ A). The data used to make these maps have many limitati ons. Any interpretation ofthe maps should consider the underlying data and the associated limitation s carefully. The small est areas shown on the maps within each state are Crop Reporting D i stricts (CRD). CRDs are defined by USDA and each consists of multiple counties that have similar soils, growin g conditions, and farming practices. The CRDs within many states have roughly the same area. Because it is not feasible to conduct an agricultural survey that samples every county in the United States , the use of CRDs allow for a sample to be collected that represent a much larger area with relatively homogeneous agricultural characteristics. The numerator (annual average pounds applied) is based on private market surveys of pesticide use in agriculture averaged over the last five years (Proprietary Data , 2007-20 1 1). Th ese surveys cover about 60 crops and are targete d in states that produce the majority of the crop. Although the survey s capture most of the use of a particular acid equivalent in agriculture , there are several limita tions to these surveys.
• States with minor production of a surveyed crop are not sampled • Not all types of pesticides are surveyed in every crop in every year • Many spec ialty crops with very small acreages are not included in the s urvey The result of these limitations is that CRDs that show no usage may actually have a small amount of the acid equivalent being used. The denominator (1,000 Acres ofland in farms) was selected from the Census of Agriculture (USDA, 2007) to represent agricultural acreage that is actively managed and includes most of the areas treated with pesticides. The category "Land in Farms " is defined by the Census of Agriculture as being made up of four components: • Total cropland • Permanent pasture • Total woodland • Land in farmsteads , buildings, livestock facilities , ponds , roads, wasteland , etc. This category includes land in the various USDA conservation programs. It should be noted that the Census of Agriculture does not include grazing land rented (on a per-animal basis) from the Bureau of Land Management or Forest Service, thus it is an underestimate of the land being 

### managed for agricultural purposes. Page 10The reader should pay particular attention to the figure legends and realize th at a map prepared for a particular chemical is not directly comparable to a map prepared for a di f ferent chemical. Scale and units of measurement do matter and may be different between map s .

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