UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON

. D C

. 20460 

### SEP 0 82014
OFFICE OF CHEMICAL SAFETY lt.Nn Prll I IITinM**P~I=\/~P\!T nN**  MEMORANDUM
SUBJECT: FROM:

THRU: BEAD Chemical Profile for Registration Review: Sethoxydim (121001) Sunil Ratnayake, Biologist Biological Analysis Branch CynthiaDoucoure, Environmental Protection Specialist (/

# ~ Science Information and Analysis Branch Stephen Smearman, Economist

# k,x;,.J,417**~** Economic Analysis Branch ' Biological and Economic Analysis Division (7503P) Arnet Jones, Chief Biological Analysis Bran Diann Sims, Chief Science Information and

### Anal~ysis Branch

### ~ Timothy Kiely, Chief 

## 'M._ Economic Analysis Branch · Biological and Economic Analy Division (7 ) TO: Neil Anderson, Chief Tom Moriarty, Team Leader Risk Management and Implementation Branch I Pesticide Re-evaluation Division (7508P)


### ProductReview Panel date: July 30,2014

Page 1 of10SUMMARY Sethoxydim was first registered inthe U.S. in 1994 as a selective post-emergence herbicide to control annual and perennial grass weeds in grains, fruit orchards, tree nuts, vegetable crops, herbs, and non-agricultural sites listed under the use sites. Overall use ofsethoxydim inthe U.S. has declined considerably since 1998. However, based onthe available percent crop treated (PCT) data during the period from 2004 to 2012, sethoxydim is reportedly used on over 50 crops and appears to still play a relatively important role in control ofweeds indry beans/peas (30% PCT), green beans (10% PCT) and watermelons (10% PCT). During the period from 2006 to 2012, states withhighest agricultural usage were North Dakota (45%), California (10%), and Minnesota (7%). Available proprietary data also shows a decrease inuse ofsethoxydim inthe non-agricultural market. In2004, approximately 29,000 pounds a.i. were reportedly applied inthe professional turfand ornamental markets compared to 6,000 pounds a.i. in 2011. Halfofthis amount was applied onturffarms.
INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to undergo registrationreview. The anticipated audience consists ofa team ofEPA staffcurrently evaluating the registration status of sethoxydim, and eventually the general public. This documentbuilds upon the data BEAD provides inthe Label Use Information System (LUIS) reports and the Screening Level Usage Analysis (SLUA) to Registration Reviewteams. The document is based on information and data available to BEAD as ofApril2014.

HISTORY OF BEADASSESSMENTS FORSETHOXYDIM Sethoxydim was registered in 1994 as a selective post-emergence herbicide to control annual and perennial grass weeds inbroad-leaved vegetable, fruit, nut, field, and ornamental crops. The Reregistration Eligibility Decision (RED) was signed in September 2005. BEAD prepared a Screening Level Usage Analysis (SLUA) in May 2014, which showed reported usage ofsethoxydim on over 50 crops during the 2004-2012 time frame. The crop with the highest average percent crop treated (PCT) was dry beans/peas (30%) onwhich an average of 100,000 pounds a.i. was applied. Other crops worth noting include green beans and watermelon, both with an average of 10% PCT and soybeans, where 30,000 pounds a.i. were applied but with an average <1% PCT due to the large number ofacres ofsoybeans inproduction. Benefits Assessments- A search ofBEAD's Official Records data base for BEAD benefits assessments specifically for sethoxydim did not find any records ofprior BEAD assessments in the last 1 0 years. Page 2 oflOEmergency Exemptions- a searchofBEAD's Official Records did not fmd any Section 18s requests for sethoxydim inthe last 8 years. Emergency exemptions may indicate thatthere is a need for a particular chemical that is notregistered for use on a particular site. Approval ofan emergency exemption request may yield informationthrough the emergency exemptionprocess about a particular chemical's importance orvalue that is not found in other EPA records. However, a lack ofSection 18 assessments by BEAD does not specifically indicate the relative importance ofthe chemical.


### COMMON FORMULATIONS AND APPLICATION METHODS Sethoxydim is commonly formulated as an emulsifiable concentrate which is applied using handheld sprayers, tractor mounted ground boom sprayers, orusing aerial application method
. 

### USE SITES Agricultural Use Sites: Sethoxydim is registered for use on grains, fruit, tree nuts, vegetables and herbs. Non-Agricultural Use Sites: Sethoxydimis registered for use on non-crop areas including ornamentals and flowering plants, recreational areas, rights-of-way, along fences, hedgerows, and public and commercial buildings/structures.


### SETHOXYDIM USAGE Agricultural Usage Trend According to proprietary market research surveys, use ofsethoxydim in the U.S. has decreased steadily since 1998 as shown in Figure 1. Similartrends were found for the total areatreated with sethoxydim as shown inFigure 2. Duringthis period, approximately 357,000 pounds a.i. were applied on average annually to 2,140,000 acres at an overall application rate of0.2lb a.i. per acre.

Page 

### 3 oflOFigure 1. Sethoxydim Usage: Pounds AI Applied, 1998-2012

"C

.!!:! 0.. 0. <( <i. VI "C c: ::J 0 0.. 1,000,000

0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Source: EPA Proprietary Data, 1998

-2012
Figure 2: Sethoxydim Usage: Total Area Treated (acres), 1998-2012

"C QJ

..... ra QJ

....Ira QJ

.... <( iii 0 1- 5,000,000

0 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Year Source: EPA Proprietary Data, 1998-2012
Page 4 oflOAgricultural Usage: Top Crops Based on available proprietary data, sethoxydim is reported to be used on over 50 crops inthe U.S. The average annual use ofsethoxydim in terms ofpounds a.i. applied has decreased in recent years (2006-2012) by 62%. The top crops treated with sethoxydimhas also shifted in recent years from a predominant use on soybeans in earlier years to a predominant use on dry beans/peas in recent years. The usage on other top crops in recent years include soybeans, alfalfa, oranges, and peanuts as shown in Table 1below. The average a.i. application rate has remained consistent for the top crops during the earlier and recentperiods except for oranges where it is applied at a higherrate (0.4lbs a.i per acre) than othertop crops as shown in Table 1. Table 1. Sethoxydim: Comparison ofUsage on Crops between 1998-2005 and 2006-2012 Timeframes. 1998-2005 2006-2012 AvgAnnualLbsA.l. Applied= 502,000 AvgAnnual LbsA.l. Applied= 190,000 Crop Proportion of Avg. A.I. Rate Crop Proportion of Avg. A.I. Rate Total Lbs A.I. ofApplication Total LbsA.I. ofApplication AJmlied (lb a.i./acre) Applied (lb a.i./acre) Soybeans 43% 0.2 Dry Beans I 51% 0.1 Peas Dry Beans 12% 0.1 Soybeans 8% 0.2 /Peas Sunflowers 12% 0.2 Alfalfa 5% 0.2 Alfalfa 9% 0.2 Oranges 4% 0.4 Sugar 4% 0.1 Peanuts 4% 0.2 Beets Peanuts 3% 0.2 Other* 28% 0.1-0.4 Other* 17% 0.1-0.4 *Other crops include nut crops, pome fruit, stone fruit, leafy & stem vegetables, root crop vegetables, cucurbits, com, cotton, fallow, citrus, small fruits, seed & pod vegetables, pasture/range, fruiting vegetables, tobacco, and wheat. Source: Propnetary Data, 1998-2012
Agricultural Usage: Top States Based on available proprietary data, sethoxydim is reported to be used in over 40 states inthe U.S. The average annual use ofsethoxydim interms ofpounds a.i. applied has decreased in recent years as described in Table 1. North Dakotahas remained the predominant user of sethoxydim andhas more than do
. ubled its usage in recent years (Table 2). Othertop states for use ofsethoxydim inrecent years include California, Minnesota, Florida, Georgia, and Wisconsin as shown inTable 2 below. The average a.i. rate ofapplication has remained consistent for the top states during the earlier and recent periods; however, sethoxydim is applied in California and Florida at a higherrate (0.3 lbs a.i per acre) as shown in Table 2.

Page 5 oflOTable 2. Sethoxydii:n: Comparison ofUsage in States between 1998-2005 and 2006-2012 Timeframes. 1998-2005 2006-2012 AvgAnnualLbsA.l. Applied= 502,000 AvgAnnual LbsA.l. Applied= 190,000 State Proportion Avg.A.I. State Proportion Avg.A.I. ofTotal Lbs Rate of ofTotal Lbs Rate of A.I. Applied Application A.I. Applied Application (lb a.i./acre) (lb a.i./acre) North Dakota 20% 0.1 North Dakota 45% 0.1 Illinois 10% 0.2 California 10% 0.3 Minnesota 8% 0.1 Minnesota 7% 0.1 California 7% 0.3 Florida 6% 0.3 Iowa 7% 0.2 Georgia 4% 0.2 South Dakota 7% 0.2 Wisconsin 4% 0.2 Other 41% 0.1-0.4 Other states include AL, AZ, AR. CO, CT, DE, FL, Other states include AL, AZ, AR, CO, CT, DE, GA, ID, IN, KS, KY, LA, ME, MD, MA, MI, MS, ID, IL, IN, lA, KS, KY, LA, ME, MD, MS, MI, MO, MT, NE, NV, NJ, NM, NC, OH, OK, OR. PA MS, MO, MT, NE, NJ, NM, NY, NC, OH, OK, SC, TN, TX, UT, VA, WA, WI, & WY OR. PA, SC, SD, TN, TX, VA, WA, & WY Source: Propnetary Data, 1998-2012 Agricultural Use Intensity ofSethoxydimUse inthe U.S. Anothermeasure ofusage is the use intensity. Inthis analysis, the use intensity is expressed as the average annual amount (inpounds) ofthe active ingredient appliedper 1,000 acres ofcrop acres grown. This differs from the applicationrate, which is expressed as thepounds a.i. applied per treated area. Figure 3 spatially represents the use intensity for sethoxydim in the U.S. during the 2008-2012 timeframe, which appears to be greater inNorth Dakota due to high usage of sethoxydim on dry beans/peas and in Californiadue to relatively high usage on alfalfa, almonds and wine grapes. The available data also shows use intensity ofsethoxydim in Massachusetts. This is due to relatively highpercentage ofsethoxydim use on lowpumpkin and squash acreage. For more information about this map, see Appendix A.

Page 6 oflOFigure 3. AnnualAverageAgricultural Use Intensity ofSethoxydim (2008-2012).

PoundsActive Ingredient per 1,000 Crop Acres Grown 

## D No Data 0 <0.1 O o.1-0
.5 0
.5-2



### - 2-9


# - >9 -----,

-----------------------------------_j (Source: ProprietaryData, 2008-2012) Non-Agricultural Usage BEAD reviewed available proprietary data and found reported use on sethoxydim inthe turfand ornamental market. Non-agricultural use in terms ofthe pounds a.i
. applied has significantly declined from 29,000 pounds 2004 to 6,000 pounds in 2011 as shown inTable 3 below. 

### T bl 

### 3 S th 

### di 

### U
. T f 

### d 0

a e e oxy' m sem ur an tal M k t mamen ar e s Sector 2004 2011 (lbs a.i.) (lbs a.i.) TurfFarms 29,000 3,000 Institutional Turf n/a 1,000 Nursery 

### I Greenhouse n/a 2,000 Total 29,000 6,000 Source: Propnetary Data, 2012 Page 7 oflOBIOLOGICAL ASPECTS RELEVANT TO SETHOXYDIM Sethoxydim [2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio) propyl]3-hydroxy-2-cyclohexen-1-one] belongs to the cyclohexanedione or cyclohexenone class ofherbicides. The mode ofaction of this herbicide is inhibition oflipidbiosynthesis. Sethoxydim inhibits the acetyl-CoA carboxylase (ACCase) which is a key enzyme inthe lipid biosynthesis pathway. This herbicide is used for the post-emergence control ofcertain annual and perennial grass weeds. However, it has little or no impact onbroadleafweeds orwoody plants. Sethoxydim is rapidly absorbed by the foliage and translocated throughout the plant. Soon after the application ofsethoxydim, growth ofsusceptible weeds ceases and young and actively growing tissues are affected first and leafchlorosis and necrosis canbe observed (Herbicide handbook, 2007).
ROLE OF SETHOXYDIMIN PESTMANAGEMENT Sethoxydim is registered for the post-emergence control ofannual and perennial grass weeds in grains fruit orchards, tree nuts, vegetable crops, and herbs and non-agricultural sites. Based on the available usage information during the period from 2006 to 2012, sethoxydim plays a relatively important role in control ofweeds in dry beans and peas. According to a publication from University oflllinois, on weed control ofagricultural crops, post-emergence treatments of sethoxydim canbeused to control many annual and perennial grass weed species including, bamyardgrass 

### (Echinoch/oa crus-galli), crabgrass 

### (Digitaria sanguinalis), giant foxtail 

### (Setaria faberi), fall panicum 

### (Panicum dichotomiflorum), sandbur 

### (Cenchrus incertus), shattercane 

### (Sorghum bico/or), andjohnsongrass 

### (Sorghum ha/epense) (Illinois Agricultural Pest Management Handbook, 2008). However, the use ofsethoxydim in the U
.S. has decreased steadily since 1998 (Figure 1 ). This could be due to the development ofresistant weeds as a result ofextensive use ofherbicides with the mode ofactionbelong to the sethoxydim as well as the use ofroundup ready soybean varieties inthe U.S. soybeanproduction. According to a survey onherbicide resistant weeds, 15 weed species have developed resistance to the mode of action ofherbicides belongs to sethoxydim. (Heap, Undated). INFORMATIONTHAT MAY BE USEFUL FORBEAD'SFUTURE WORKON SETHOXYDIM The Agency currently does nothave important information on sethoxydim. Obtaining the following usage information may improve future assessments conducted by the Agency related to the use and importance ofsethoxydim:

• Pounds a.i. applied, average applicationrates, and average number ofapplications in noncrop uses including recreational areas, rights-of-way, along fences, hedgerows, and public and commercial buildings/structures.

Page 8 oflO

### REFERENCES EPAProprietary Data, 1998-2012. EPA, Sethoxydim Screening Level Usage Analysis (SLUA), May 2014. Heap, I. (Undated). The International Survey ofHerbicide Resistant Weeds. Online. Internet. Tuesday, February 11, 2014. Available at: http://www.weedscience.org/summary/CountrySummary.aspx
. Accessed Date. June. 18,2014. Herbicide Handbook. 2014. lOth edition. Weed Science Society ofAmerica. Sethoxydim. Pp 413-414. 810 E. lOth Street, Lawrence, KS 66044-8897. Illinois Agricultural Pest Management handbook. 2008. Online Publication ofUniversity of Illinois Urbana Champaign. http://ipm.illinois.edu/pubs/iapmh/02chapter.pdf
. Accessed onJune 17, 2014. USEPA. 2005. Registration Eligibility Decision (RED) for Sythoxydim. Online Publication. Available at: http://www.epa.gov/oppsrrd1 /REDs/sethoxydim red.pdf
. Accessed onJune 16, 2014.

Page 9 oflOAPPENDIXA 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 inthe amount ofa pesticide used across agricultural land. The calculated values presented in the map are not equivalentto an application rate (lb a.i./A). The data used to make these maps have several limitations. Any interpretation ofthe maps should considerthe underlying data and the associated limitations carefully. The numerator (annual average pounds applied) is based on private 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 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 minorproduction ofa surveyed crop are not sampled • Not all types ofpesticides are surveyed in every crop in every year • Many specialty crops withvery 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 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 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. Itis 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 that reported by crop acres grown inthe survey because eitherthat 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.

Page 10 oflO