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

### APR 2 8 

### 2014
OFFICE OF CHEMICAL SAFETY

. AND POLLUTION PREVENTION



### MEMORANDUM

SUBJECT:

FROM:

THRU:

TO: Use and Usage, Pest Management Role, and Response to Comrp.ents for Hexythiazox (PC 128849) in Support ofRegistration Review Clayton Myers, Ph

.D, Biologist-tl Biological Analysis Branch

### ~\ Elizabeth Hill, Economist Economic Analysis Branch Jihad Alsadek, Ph.D, Economist

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# A~ Science Information and Analysis Branch Biological and Economic Analysis Division (7503P)
Arnet Jones, Chief

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# , Economic Analysis Branc'kJ 

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Diann Sims,

# Chie~**~-'0t-~""'P.i..­** Science Information and Anal is Branch Biological and Economic Analysis Division (7503P) Molly Clayton, Chemical Review Manager Risk Management and Implementation Branch 3 (RMIB 3) Pesticide Re-evaluation Division (7508P)

Product Review Panel: Apri123, 2014

1SUMMARY Hexyt:hiazox is inthe proposed decision making phase ofregistration review. BEAD is providing here use/usage, IPM/alternatives information, and responses to public comments to help inform risk management decisions

. Hexyt:hiazox is an IRAC Group 10 miticide registered for use onvarious fruit, nut, vegetable, and row crops, as well as on turf, and residential plants, with applications limited to once per year. It can be applied as a liquid foliar spray by air or ground application equipment. The most recent Screening Level Usage Analysis (SLUA) data (2004-2012) showthat the most significant usage is on almonds, strawberries, stone fruits, caneberries, dates, tangerines, and walnuts.
While hexythiazox can be applied

. at almost any time inthe growing season, its ovicidal activity lends itselfto mostly early season applications targeting the egg stage ofphytophagous mites. While there are a number ofalternative miticides available for the pest mite species inthe activity spectrum for hexythiazox, there are relatively few ovicides. Clofentazine and etoxazole are other Group 10 ovicidal chemicals that are thought to have a similar mode ofaction and pest spectrum. However, not all crops have registrations for these alternatives. For dates, citrus, alfalfa (hay production) and sweet corn, hexythiazox is the only ovicidal chemical registered for mite control. Costs ofapplication ofhexythiazox are comparable to etoxazole.

BEAD'S USE/USAGE DATA Hexythiazox labels limit applications to once per year on all crops. OPP's Screening Level Usage Analysis (SLUA) (OPP/BEAD, 2014) indicates that more than 20 surveyed crops are treated with hexyt:hiazox. The data show 25% ofstrawberries are treated, 15% each for caneberries, dates, tangerines and nectarines, 10% each for almonds and peaches, and 5% each for apricots, plums/prunes and walnuts are treated withhexythiazox Pluots are also treated, but a percenttreated value was not calculated for this crop, which were derived solely from California data. The remaining surveyed crops are treated at an average ofless than 2.5% ofacreage, respectively. Total annual agricultural usage averaged 25,000 lbs peryear for the time period 2004-2012 with almonds accounting for the highestpercentage oftotal pounds applied, with an average of 10,000 lbs applied annually overthe same time period (OPP/BEAD, 2014). By comparison, overall nursery and floriculture usage was reported as 1,500 lbs in 2006 and 700 lbs in 2009 (USDA/NASS, 2009).
Available use datafor hexythiazox from 2008-2012 (EPA Proprietary Data, 2014) showthat average application rates for hexythiazox are belowthe maximum label application rates, except for pecans, and that use was less than 100 lbs and only in one year. While hexythiazox is applied by both ground and aerial application, use datafrom 2008-2012 showthat only for almonds in 2011 and 2012 was the average aerial application rate equal to the maximum label application rate. For some years, ground applications to caneberries, cherries, grapes and pecan show average rates equal to the maximum label rate, but not consistently so. Formost crops, ground applications are made at rates belowthe respective maximum label application rates. Table 1

2below lists the average application rates ofhexythiazox by crop for the time period 2008-2012. Please note that this table was derived from an independent usage query (EPA Proprietary Data) and thus, might not exactly match the figures listed for EPA's SLUA (OPP/BEAD 2014), which captured a different time frame and included California crops not surveyed in EPA'sproprietary data source. 

### T bl 1 

### A

a e . verage AIRtbC a e )y ti H th" 

### rop or exy1 Iazox, 2008 2012


# - Average AI Rate/ Acre, Crop (2008-2012, 

### Calculated Annually) Apples 0.13 Pears 0.15 Cane berries 0.18 Strawberries 0.17 Com 0.09 Sweet Com 0.13 Grapes, Raisin 0.16 Grapes, Table 0.16 Grapes, Wine 0.12 Dry Beans/Peas 0.02 Beans (Snap, Bush, Pole, String) 0.16 Walnuts 0.14 Pecans 0.19 Almonds 0.14 Tomatoes 0.09 Potatoes 0.06 Cherries 0.15 Peaches 0.14 Plums/Prunes 0.14 Oranges 0.15 Source: EPA Propnetary Data, 2008-2012.



### IPM IMPORTANCE AND ALTERNATIVES Hexythiazox is classified by the Insecticide Resistance Action Committee (IRAC) as a Group 10 miticide. Group 10 is a somewhatnebulous IRAC classificationreferred to as "mite growth inhibitors." While the specific modes ofaction have not been well-described for this group, hexythiazox, clofentazine, and etoxazole are presumedto have similar modes ofaction due to observed cross-resistance and shared ovicidal activity (IRAC, 2014). Hexythiazox, like the other Group 10 miticides, has mostly ovicidal activity and has little to no efficacy against adult mites. Hexythiazox is known to be very effective against the eggs of phytophagous mites, including Europeanred mites, two-spotted spider mites and other major pest species. Ovicidal efficacy ofthese miticides is well-documented in extension literature, and for several ofthe crops where both are registered, hexythiazox and clofentazine are 3recommended as functionally equal materials for mite control. While hexythiazox canbe applied at any time that mites are actively laying eggs, most pest management recommendations, especially for specialty crops including citrus (UC, 2008), caneberries (UC, 2010a) strawberries (Burrack et al., 2012; UC, 2010b), and almonds (UC, 2012) suggest early season application timing (sometimes during or immediately following bloom) in orderto reduce subsequent mite outbreaks later in the growing season. While for many crops there are a number ofother registered miticide alternatives that target adults and that make effective resistance management partners (i.e., materials in several other IRAC groups), there are no otherregistered ovicides outside ofthe Group 10 chemicals: hexythiazox, clofentazine, and etoxazole. For some crops, not all ofthese Group 10 chemicals are registered for use. For dates, citrus, sweet com, and alfalfa (grown for hay) in particular, hexythiazox is the onlyregistered Group 10 chemical that is available for use. Priorto eventual Section 3 registrations, emergency exemptions were reviewed by EPA under FIFRA Section 18 for uses on strawberries (Burr and Hernandez, 1997; Gross and Halvorson, 2000), hops (Gross and Halvorson, 1998), dates (Halvorson and Hennessey, 1998), cotton (Gross and Halvorson, 1997), com (Brassard and Faulkner, 2004) and sweet com grown for seed (Mallampalli and Faulkner, 2009, 2010). Minimally, this indicates that in the past there have been few available miticide alternatives for some crops and that urgent needs have existed for use ofthis chemical for mite control. Relative to other Group 10 miticide alternatives, the cost ofapplication for hexythiazox is comparable to the alternative ovicide etoxazole (typically $40-55 per acre for most crops, depending on the application rates), but more expensive than clofentazine, which averages $10- 20 less per acre for some crops (EPA Proprietary data, 2014). Clofentazine, while cheaperper acre, is not registered on as many crops as eitherhexythiazox oretoxazole. On the whole, hexythiazox and etoxazole both have a higher average costper acre than some ofthe adulticidal alternatives such as abamectin, spirodiclofen, pyridaben, and fenbutatin oxide. However, some adulticides may be applied multiple times, depending upon both populationpressure and the success ofearly season mite management efforts. So in some instances, one successful early season application ofa more narrow-spectrum and expensive ovicide such as hexythiazox can preclude the need for subsequent additional applications ofadulticidal alternatives due to both efficacy against the target pest and conservation ofbeneficial predator species.



### BEAD'S RESPONSE TO COMMENTS
EPA-OPP received public comments inresponse to the posting ofHexythiazox work plans and documents to docket EPA-HQ-OPP-2006-0114-0023. Inthis section, BEAD is responding to two comments related to the usage and benefits ofhexythiazox, submitted with regard to the registration review process. Washington Hop Commission Comment,Apri/13, 2007: "Hexythiazox is an extremely importantpestmanagement tool for the US. hop industry for controlling Two-spottedspider mite (I'etranychus urticae), which is a majorpest of the crop. We have very limitedregistered



### 4plantprotection tools for thispest, which is an annualproblem on nearly 100% ofUS acreage. Hexythiazox is a very effective ovicide (all other registeredmiticidesprimarily target motile forms of this pest). It is important for resistance managementprograms, and fits extremely well with the hop industry's/PMstrategies, including conservation biocontrol. Due to hexythiazox's relative level of safety to importantpredator species, it can be usedwith minimal disruption of beneficialpopulations. Loss of thisproductwouldseriously jeopardize the ability to control mites on nearly 30,000 acres ofUS. hops, located in the Pacific Northwest. This represents 100% ofUS. commercial hopproduction andnearly 30% of the world's supply." BEAD Response: BEAD appreciates the information onthe importance ofhexythiazox for control oftwo-spotted spider mite on hops and the prevalence ofthis pestthroughoutthe hop growing region ofthe United States. Based upon published efficacy ratings and extension recommendations for other crops, BEAD concurs that hexythiazox is an effective ovicidal material for control ofthis and otherphytophagous mite pests. BEAD notes that a number of extensionpublications rate hexythiazox as having low toxicity to beneficial mites and predator species, albeit mainly via field observations rather than laboratory toxicology studies. BEAD notes that etoxazole, another IRAC Group 10 miticide with ovicidal activity is now registered for use on hops, so this would serve as one ovicidal alternative for hops producers. In general, references directing us to additional relative performance data are helpful if/when BEAD is askedto conduct a benefit assessment. NationalAlfalfa andForageAlliance Comment, September 10, 2013: "Hexythiazox is a critically important insect management tool whichprovides effective control of the two-spotted spider mite in alfalfa seed The two-spottedspider mite canprove to be a serious arthropod pest for Western US. alfalfa seed producers. Hexythiozox (sic) is a selective ovicidal acaricide with a completely different mode of action than other registeredacaricides. When hexythiazox (sic) is appliedto spider mite infestedalfalfa seed fields itsuppressespopulations of targeted pestiferous spider mites butdoes little or no harm to thepredatory mites andother beneficial arthropods that aidin the natural biological regulation of arthropod pests. Spider mites are destructivepests which can significantly affectalfalfa seedyields. An actively feeding adult female can ingest a mass of planttissue equivalent to her bodyweight in as little as two hours. It is estimatedthat a single mite canpuncture andempty 100photosyntheticallyactive leaf cells per minute. In the PacificNorthwest, mostseed producers use IPM strategies, which include monitoringspider mite andbeneficialpredatory mitepopulations within their fields. Growers only choose to apply an acaricide like hexythiazox (sic) when spider mitepopulations appear to be on the verge of outbreakearly in the seed production season. Hexythiozox (sic) alsoprovides better environmentalsafety comparedto other acaricides registered for use on alfalfa seed "
BEAD Response: BEAD appreciates the information onthe importance ofhexythiazox for control oftwo-spotted spider mite on alfalfa grown for seed, onthe impact ofdamage from spider mites to yields ofalfalfa seed, and ontypical timing and threshold information for applications ofhexythiazox. Baseduponpublished efficacy ratings and extension recommendations for other crops, BEAD concurs that hexythiazox is an effective ovicidal material for control ofthis and otherphytophagous mite pests. BEAD notes that there are other miticides that confer ovicidal efficacy in IRAC Group 10, including etoxazole, which is also registered for use on alfalfa grown for seed. BEAD notes that a number ofextension

5publications rate hexythiazox as having lowtoxicity to beneficial mites and predator species, albeit mainly via field observations rather than laboratory toxicology studies. In general, references directing us to additional relative performance data are helpful if/when BEAD is asked to conduct a benefit assessment.



### REFERENCES Brassard, D., and J. Faulkner, 2004. Review ofa Request for Emergency Exemption of Hexythiazox in Texas for Use on Comto Control Mites. OPP-BEAD Memorandum, July 29, 2004. Burr, W. F., and F. Hernandez, 1997. Emergency Exemption Request from the California Department ofPesticide Regulation for the Use ofHexythiazox (Savey) on Strawberries (97-CA45). OPP-BEAD Memorandum, August 20, 1997. Burrack, et al., 2012. Southeast Regional Strawberry Integrated Pest Management Guide, Entomology Section. http://www.smallfruits.org/SmallFruitsRegGuide/Guides/20 12/2012 strawberry.pdf EPA, 2014. Proprietary Data. Gross, W., and A. Halvorson, 1997. Review ofthe Emergency ExemptionRequest from California (97-CA-31) for Use ofHexythiazox (Savey) to Control Spider Mites onCotton. OPPBEAD Memorandum, June 2, 1997. Gross, W., and A. Halvorson, 1998. BEAD's Review ofDocumentation in Support ofan Emergency Exemption for the Use ofHexythiazox (Savey) and Cyhexatin (Pennsty) to Control the Two-Spotted Spider Mites on Hops in Idaho, Oregon, and Washington. OPP-BEAD Memorandum, April 8, 1998. Gross, W., and A. Halvorson, 2000. BEAD's Review ofDocumentation Submitted in Support of anEmergency Exemption for the Use ofHexythiazox (Savey) to Control Two-spotted Spider Mites onFlorida Strawberries (00-FL-04). OPP-BEAD Memorandum, March 21,2000. Halvorson, A., and M. Hennessey, 1998. BEAD Review ofEmergency Exemption Application from the State ofCalifornia for Hexythiazox (Savey) Against Banks Grass Mite on Dates. OPPBEAD Memorandum, April 2, 1998. IRAC, 2014. Insecticide Resistance Action Committee Mode ofAction Classification Scheme, Updated February 2014. http://www.irac-online.org/documents/moa-classification/?ext=pdf Mallampalli, N., and J. Faulkner, 2009. Review ofan Emergency Exemption Request for Hexythiazox in Idaho for Use On Sweet Com Grown for Seed to Control Mites (09-ID-04). OPP-BEAD Memorandum, June 8, 2009.

6Mallampalli, N. and 

### J. Faulkner, 2010. Review ofan Emergency Exemption Request for Hexythiazox in Idaho for Use on Sweet Com Grown for Seed to Control Mites (10-ID-03). OPP-BEAD Memorandum,**M~y** 27, 2010. OPP/BEAD, 2014. Screening Level Usage Analysis (SLUA), Hexythiazox. UC, 2008. University ofCalifornia IPM Pest Management Guidelines, Two-spotted Spider Mite, Citrus. Updated September, 2008. http://www.ipm.ucdavis.edu/PMG/r10740021l.html UC, 2010a. University ofCalifornia IPM Pest Management Guidelines, Two-spotted Spider Mite, Caneberries. Updated March, 2010. http://www.ipm.ucdavis.edu/PMG/r714002ll.html UC, 2010b. University ofCalifornia IPM Pest Management Guidelines, Spider Mites, Strawberries. Updated May, 2010. http://www.ipm.ucdavis.edu/PMG/r734400lll.html UC, 2012. University ofCalifornia IPM Pest Management Guidelines, Webspinning Spider Mites, Almonds. Updated November, 2012. http://www.ipm.ucdavis.edu/PMG/r3400211.html USDA-NASS, 2009. NASS Nursery and Floriculture Chemical Usage Query, http://www.nass.usda.gov/Data and Statistics/PreDefined Queries/2009 Nursery and Floriculture Chern Usage/index.asp



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