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

## DEC.022014

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION MEMORANDUM SUBJECT:

FROM:

THRU: BEAD Chemical Profile (BCP) for Registration Review: Cycloate (041301)

Sunil Ratnayake, Biologist 

# /1.·..} "'**~** Biological Analysis Branch

# ~**~** 

# Oi - j SepehrHaddad, Environmental Protection Specialist 

# IJ**'f./~** Science Information and Analysis Branch Stephen Smearman, Economist Economic Analysis Branch Biological and Economic Analysis Division (7503P)
Arne!Jones, Chief 

# /J**"'~ Biologi~al**  Analysis Branch

# ~u

# . .**~** D1ann Stms, Chtef

## jj**-: ~**  jlf.

## ~**~v** 

# 0) Science Information and Analysis Branch t/ Timothy Kiely, Chief 

# gj: \A

## 1\~ Economic Analysis Branch 

### ·v\. Biological and Economic Analysi ivision (7 ) TO: Matthew Manupella, Chemical Review Manager, RMIB II Pesticide Re-evaluation Division (7508P) 

### Peer Review Panel date: November 5th, 

### 2014SUMMARY Cycloate was first registered inthe United States in 1967 (USEPA, 2004). Cycloate belongs to the herbicide family ofthiocarbamates. Itis a systemic, broad-spectrwn, andpre-emergent herbicide registered for control ofcertain grasses and broadleafweeds intable beets, spinach, and sugarbeets. A Re-registration Eligibility Decision (RED) was completed for cycloate in 2004. Based on private market usage data from 1998-2012, usage averaged approximately 220,000 pounds active ingredient (a.i.) applied annually approximately on 100,000 acres treated. The average application rate overthis time period was 2.2 lbs a.i./acre. A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 thatprovides the percent crop treated data over the 2004-2012 timeframe. For sugarbeets and spinachthese percent crop treated values were 5 and 40 percent, respectively. There are no non-agricultural uses ofcycloate.

INTRODUCTION The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an overview ofthe pest management roles and quantitative usage information for cycloate. The BCP includes summaries ofprevious BEAD products and available public and/or private use and usage data for cycloate to describe the role ofthis chemical inpest management. Additional information on use is available the Screening Level Usage Analysis (SLUA). Information provided in this BCP may be used by stakeholders (e.g., users and registrants), OPP risk and benefit assessors, OPP risk managers, and the general public during the Registration Review process ofthis pesticide. USE SITES Agricultural Use Sites Cycloate registered agricultural use sites are table beets, sugarbeets and spinach. FORMULATIONS AND APPLICATION METHODS Cycloate is formulated as an emulsifiable concentrate liquid. As pre-plant or atplanttreatments, cycloate is applied using ground spray equipment and then incorporated into the soil mechanically orby sprinkler irrigation (chemigation). HISTORY OF CYCLOATE and BEAD PRODUCTS Cycloate was first registered inthe United States for use as a selective herbicide on sugarbeets and spinach in 1967 (USEPA, 2004). A Re-registration Eligibility Decision (RED) was completed for cycloate in 2004.

Page2A search ofBEAD's Official Records database for BEAD benefits assessments specifically for cycloate did not find any records ofprior BEAD assessments specifically for this chemical in the last 10 years. A Screening Level Usage Analysis (SLUA) was prepared by BEAD for cycloate in 2014 that provides the percent crop treated data overthe 2004-2012 timeframe for spinach (average 40 percent) and sugarbeets (average 5 percent).
No results were found in a search ofBEAD's Official Records and the OPP Section 18 (emergency exemption) database for any Section 18 requests for cycloate inthe last 10 years. Emergency exemptions may indicate that there is a need for a particular chemical that is not registered for use on a particular site. An emergency exemption request may yield information about a particular chemical's importance or value 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. 

### USAGE Agricultural Usage Based on private market usage data from 1998-2012, average annual usage was approximately 220,000 pounds active ingredient (a.i.) on 100,000 acres treated. The average a.i. rate overthis time period was pounds 2.2 lbs a.i./acre. Figure 1presents cycloate usage in pounds a.i., and Figure 2 shows total areatreated in acres overthe 1998-2012 timeframe (Proprietary Data, 1998- 2012). Figures 1 and 2 showthat overthis time period in terms ofpounds applied and acres treated there has been a sharp decrease in use. 

### FIGURE 1. 

### Cycloate Usage in Pounds Active Ingredient (1998-2012) 800,000

'0 Q) Ci c. <(**~** "' '0 c:::: ::I 0 Q,

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### -fl -fl Years Source: Proprietary Data, 1998-2012

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### FIGURE 2. Cycloate Total Area Treated in Acres (1998-2012) 350000 VI C1l ,_ u 

### =:s "'C C1l



### .... ro C1l ,_Iro C1l ,_ <( Iii



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Source: ProprietaryData, 1998-2012 Sincethe RED was issued in2004, Table 1 shows a comparison oftimeframes before and after the issuance ofthe document. The crop with the most pounds applied during the**2001-200~** timeframe was sugarbeets while inthe 2008-2012 timeframe the top crop was spinach with 98 percent oftotal pounds applied. The average annual usage inpounds a.i. applied has decreased

. sharply from approximately 237,000 lbs (a.i.) inthe earliertimeframe to approximately 45,000 lbs/year (a.i.) in the 2008-2012 timeframe, a drop in usage ofmore than 80 percent. However, most ofthis decline is due to reduction ofuse on sugarbeets. The development ofgenetically modified sugarbeet varieties with resistance to gylphosate may have contributedto the reduction ofcycloate usage on sugarbeet production. 

### Table 1. 

### Comparison ofCrops with HighestUse ofCycloate- Percent ofTotal Lbs. Applied (2001-2005 and 2008-2012) 2001-2005 2008-2012 Average annual= 237,000 lbs/yr Average annual= 45,000 lbs/yr 

### Crop %Lbs Crop %Lbs Sugarbeet 76% Sugarbeet 2%

Spinach 24% Spinach 98% TOTAL 100% TOTAL 100% Source: Proprietary Data, 2001-2012. As shown in Table 2, Idaho, California and Michigan were the top states with the highest use of cycloate during the 2001-2005 timeframe accounting for approximately 75 percent oftotal pounds applied, while inthe latter 2008-2012 timeframe, Californiawas the top state with the highest use (92 percent oftotal pounds applied). However, total usage inpounds a.i. applied has declined more than 80 percent between the two periods.

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### Table 2. Comparison ofStateswith Highest Use ofCycloate- Percent ofTotal Lbs. AJ!Piied (2001-2005 

### and 2008-2012) 2001-2005 2008-2012 Average annual= 237,000 lbs/yr Average annual= 45,000 lbs/yr



### State %Lbs State %Lbs Idaho 41% California 92% California 23% NewJersey 3% Michigan 10% Arizona 3% Other 26% Nebraska 2% TOTAL 100% TOTAL 100% Other states in the 2001-2005 time period includes 13 additional states. Source: Proprietary Data, 2001-2012
Application Rates and Percent Crop Treated The average a.i. rate for the top crop, spinach, which accounts for 98

. Percent oftotal use in 2008- 2012 in terms ofpounds a.i. applied was 2.3 lbs a.i./acre as shown in Table 3.


### T bl 3 C I t 

### U

a e 

# . ;yc oa e se on

### T C op rops: A

### vera2e A I R t 2008 2012 

# . . a e, 

# - Annual Average AnnualAverage A vg. A.I. Rate (lbs Crop TotalAcres Pounds Treated* a.i./acres) Spinach 44,200 19,200

. 2.30 *Total Acres Treated sums all acres treated for a crop, mcludmg those acres that receive multiple treatments. Source: Proprietary Data, 2008-2012 Geographic Distribution ofCycloate Use Figure 3 provides a very broad geographical view ofthe average annual amount (in pounds) of cycloate applied per 1,000 acres ofcrop acres grown. The calculated values presented inthe map are not equivalent to an application rate (lb a.i./A), therefore, the map may show areas of high use intensity that do not necessarily correspond to the states listed in Table 2. However, in this case, California and NewJersey are the states that use approximately 95 percent ofthe total pounds a.i. used and are also the states that show high use intensity as depicted in the map. Please see Appendix A for a more detailed explanation ofthe information presented onthe map.

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### FIGURE 3. AnnualAverage Agricultural Use Intensity ofCycloate (2008-2012)

Pounds Active Ingredient per 1,000 Crop Acres Grown 0 <0.1 

## 0 o.1-1.4

. 1

.5-4

.8

- >4.8 

## UNo Data



### BIOLOGICAL ASPECTS RELEVANT TO CYCLOATE Cycloate belongs to the family ofthiocarbamate (Group 8) herbicides. It is a broad-spectrum, pre-emergence herbicide used for the control ofcertain grasses and broadleafweeds in table beets, spinach, and sugarbeetproduction. The mechanism ofaction ofthis herbicide is inhibition ofthe enzyme fatty acid elongase. Inhibition ofthis enzyme interferes withthe biosynthesis oflong-chain fatty acids and lipids

. Fatty acid and lipids are essential constituents ofplant waxes and suberin (Magnucka et al., 2009). Following the application ofcycloate, susceptible weeds fail to emerge as the coleoptile ofgrass weed species or hypocotyl ofbroadleafweed species cease growth beneaththe soil (Herbicide Handbook, 2014)

.

Page 6ROLE OF CYCLOATE IN PEST MANAGEMENT Cycloate is registered as a pre-emergence herbicide for control ofcertain grasses, broadleaf weeds, and sedges (Cyperus spp.) inbeets and spinach. Major grassyweed species controlled by cycloate are barnyardgrass (Echinochloa spp.), crabgrass (Digitaria spp.), foxtails (Setaria spp.) and wild oats (Avenafatua). Also, cycloate is applied for control ofbroadleafweeds such as black nightshade (Solanum nigrum), hairy nightshade (Solanum villosum), henbit (Lamium spp.), lambsquarters, (Chenopodium album), purslane (Portulaca oleracea), redroot pigweed (Amaranthus retrojlexus), shepherd's-purse (Capsella bursa-pastoris), and small stinging nettle (Urtica urens) (Cycloate Herbicide Profile, 1985). Compared to the timeframe of2001 to 2005, use ofcycloate on sugarbeets declined significantly from 2008 to 2012 (Table 1). The development ofgenetically modified sugarbeet varieties with resistance to gylphosate may have contributedto the reduction ofcycloate usage on sugarbeet production. From 2008 to 2012, 98 percent oftotal average annual usage ofcycloate was on spinach, with about 92 percent ofaverage yearly usage ofcycloate was in California spinach. About 40 percent ofthe crop is treated with cycloate, suggesting that this herbicide is important in U.S. spinachproduction. Stinging nettle (Urtica urens), annual bluegrass (Poa annua), sowthistle (Sonchus oleraceus), prickly lettuce (Lactuca serriola), little mallow (Malvaparviflora), London rocket (Sisymbrium irio) shepherd's-purse (Capsella bursa-pastoris) and pigweeds (Amaranthus spp.) are some of the troublesome weeds found in spinach production (Univ. ofCalifornia, 2011). Ofthese weeds, little mallow (Malvaparviflora), purslane (Portulaca oleracea), shepherd's-purse (Capsella bursa-pastoris), and redroot pigweed (Amaranthus retrojlexus) are the main weed species targeted by cycloate (Proprietary data, 2014).
In California spinachproduction, several herbicide options are available as alternatives to cycloate. Ofthese herbicides, S-metolachlor is used as a pre-emergent herbicide. The weeds controlled by S-metolachlor are similarto those controlledby cycloate. However, S-metolachlor has a 50 day pre-harvest interval which limits the use ofS-metolachlor in fresh market spinach. However, S-metolachlor may be useful in longer seasonprocessing spinach where a 50-day preharvest interval does notpreclude its use (Univ. ofCalifornia, 2014 b). Other alternatives to cycloate include metam sodium (soil fumigant) and herbicides such as glyphosate, pelargonic acid**(pr~-plant** foliar applied herbicides) and post-emergent foliar applied herbicides such as sethoxydim, and clethodim which are registered for grass weed control in California spinach (Univ. ofCalifornia, 2014 b). According to the International Survey ofHerbicide Resistant Weeds, biotypes offive weed species have developed resistance to·the mechanism ofaction ofthiocarbamates inthe United States. These weed species**~e:** wild oats (Avenafatua), barnyardgrass (Echinochloa crus-galli), early water grass (Echinochloa oryzoides), late watergrass (Echinochloaphyllopogon), and annual ryegrass (Poa annua) (Heap, Undated).

Page 7DATA NEEDS The Agency currently does not have complete information for cycloate. Obtaining the following information may improve future assessments conducted by the Agency related to the use and importance ofthis herbicide:
Use and usage information ofcycloate on table beets may be needed for risk assessments. REFERENCES BEAD. 2014. Cycloate Screening Level Usage Analysis. Biological and Economic Analysis Division, Office ofPesticide Programs, US Environmental Protection Agency. Cycloate Herbicide Profile. 1985. Online Publication. Available at: http://pmep.cce.cornell.edu/profiles/herb-growthreg/cacodyliccymoxanillcycloate/herb-prof-cycloate.html. Accessed on Oct. 14, 2014. Heap, I. (Undated). The International Survey ofHerbicide Resistant Weeds. Online Publication. Available at: http://www.weedscience.org/summary/CountrySummary.aspx

. Accessed on October 17, 2014. Herbicide Handbook. 2014. 

### lOth edition. Weed Science Society ofAmerica. Cycloate. Pp 123-124. 810 E. lOth Street, Lawrence, KS 66044-8897. MagnuckaE.G., Suzuki Y., Pietr S.J., Kozubek A., and R. Zarnowski. 2009. Cycloate, an inhibitor offatty acid elongase, modulates the metabolism ofvery-long-sidechain alkyl resorcinols in rye seedlings. Online Publication. Available at: http://www.ncbi.nlm.nih.gov/pubmed/19479950

. Accessed on Oct. 14, 2014. Proprietary Data. 1998-2012. University ofCalifornia. 2011. Spinach Production in California. Publication number 7212. Online Publication. Available at: http://anrcatalog.ucdavis.edu/pdf/7212.pdf Accessed on Oct. 01, 2014. University ofCalifornia. IPM Online. 2014a. Information about Herbicides in Spinach. Spinach

. Online Publication. Available at: http://www.ipm.ucdavis.edu/PMG/r73270041l.html. Accessed on Oct. 22, 2014. University ofCalifornia. IPM Online. 2014b. Information about Integrated Weed Management in Spinach. Online Publication. Available at: http://www.ipm.ucdavis.edu/PMG/r732700111.html Accessed on Oct. 22, 2014. USEPA.2004. Reregistration Eligibility Decision (RED) for Cycloate. Online Publication

. Available at: http://www.epa.gov/oppsrrdl/REDs/factsheets/cycloate red fs.pdf. Accessed on Oct. 17, 2014. Page 8APPENDIX A.
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 application rate (lb a.i./ 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 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,**ther~** are several limitations to these surveys.

• States withminorproduction 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 inthe 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 inthe 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 a state is higher than that reported by crop acres grown in the survey because eitherthat state and/or crop was not included in the survey. The reader shouldpay particular 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.

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