UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D.C

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## SEP 10 2015

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: Response to Benefits and Usage Comments from Stakeholders, Received for the Dicrotophos Registration Review Docket FROM: Nikhil Mallampalli, Entomologist 

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# /k**~** Biological Analysis Branch

- Biological and Economic Analysis Division 7503P) THRU: Arnet Jones, Chief Biological Analysis Branch Biological and Economic Analysis Division (7503P) TO: Khue Nguyen, Chemical Review Manager Neil Anderson, Branch Chief**Ris~** Management and Implementatidn Branch 1 Pesticide Reevaluation Division (7508P) BEAD Product Review Panel date: August 6, 2015 INTRODUCTION In 2014, EPA released preliminary human health and ecological risk assessments in support of the registration review ofdicrotophos for public comment. In this memorandum, BEAD responds to substantive comments that addressed the usage orpest management benefits of dicrotophos in cotton (which is the only currently registered agricultural use in the United States). For these comments, anitemized summary ofeach is shown below, withthe BEAD response following immediatelybelow each comment. In general, BEAD agrees with commenters that dicrotophos is an importantpest control option where certain stink bug pests are persistent or high in populations. However, for other cotton insectpests BEAD has not changed its conclusion that growers are using several alternatives to a greater extentthan dicrotophos. Most ofthe usage information in the comments supportedthe BEAD usage memorandum that is also part ofthe dicrotophos registration review docket (EPA-HQ-OPP-2008-0440). Details ofthe comments and BEAD'sresponse follow below. Page 1of5

### Comments from the Arizona (AZ) Pest Management Center.

• Dicrotophos is used only oncotton, and exclusively for control ofbrown stink bug in AZ • Dicrotophos is used sparingly--only 12% AZ cotton acreage treated in 2013 • Without stink bug control, the industry is vulnerable to aflatoxin contamination that affects injured plantparts • The current re-entry interval (REI) of6 days is too restrictive; stakeholders wishto change it to 72 hrs. The 6 day REI prevents timely scouting and decision making in the field • Stinkbugs are responsible for about 23% oftotal losses associated with insect damage

- an economic impact equivalentto $5.9 million • In replicated field efficacy trials, d1crotophos killed the largest fraction ofbrown stink bugs • The Arizona Pest management center submitted information onuse distribution in AZ, median and 9Qth percentile use rates, and application timing 

### BEAD Response BEAD appreciates the additional information on areatreated in Arizona cotton and onthe issue with aflatoxin. The importance ofdicrotophos in recent years in Arizona cottonproduction has already been emphasized in BEAD'smemorandum to EFED (Mallampalli 

### etal. 2014). BEAD notes that several sources, including Arizona, also mentionthat acephate and bifenthrin still have good efficacy against the brown stinkbug). That said, BEAD recognizes that stink bug management has become an increasing problem in recent years and that dicrotophos is one ofa very limited set ofeffective options available to growers atthe moment. Regarding a need for a shorter REI, BEAD notes that the Worker Protection Standard (WPS) guidance allows for exemptions to permit certified crop advisors wearingthe appropriate personal protective equipment (PPE) to entertreated fields during an REI, inorderto assess the need for any additional treatment. This should provide a way to continue to use IPM tactics to manage pests. Giventhis exception, and the lack ofdetail inthis comment, it is not clearto BEAD why a shorter REI 

## is so critically needed. 

### Comments from the National Cotton Council (NCC)

• Stink bugs are the most important targetpest; NCC believes thatthere are no other effective alternatives for the management ofstinkbugs without killing beneficial insects. • Major insect pests for cotton (in general) are thrips, aphids, plantbugs, fleahoppers, stink bugs, leaf-footed bugs • Dicrotophos is critical as part ofan effective IPM system, since effectiveness ofseed treatments is limited to 30-40 days • To manage plantbugs, growers rteed to retain ability to apply dicrotophos at 0.33 lbs ai/acre three times per season, or 0.5 lbs ai/A two times per season Page 2of5• The comments from NCC included 9 letters from university experts in 8 cotton states. All oppose using untreated buffers in fields because 

### it is counter to proper IPM practices, because it allows peststo migrate back into cotton from untreated areas and places undue burden on growers, since most infestations start from the edge ofthe field. • The current 14 day retreatment interval already too restrictive, a larger interval would be worse. The 14 day retreatment interval is acceptable most ofthe' time, butproblematic during periods ofintense migration ofadult brown stink bugs to cotton. 

### BEAD Response BEAD appreciates the details provided in the NCC comments. The importance of dicrotophos as a control option for plantbugs and stinkbugs reflects the discussion in BEAD's ownusage analysis (Mallampalli 

### etal. 2014). However, proprietary data, summarized in Mallampalli 

### etal
. (2014) indicate that most growers inrecent years have applied dicrotophos no more thantwo times per season, and the average rate is, at most, about 0
.33 lb a.i./acre. BEAD also noted in 2014 that several alternatives including other organophosphates, pyrethroids, insect growth regulators, etc. are inuse for plantbugs management. For stinkbugs, the list of · alternatives is shorter, and BEAD noted in its memorandumthat for this set ofpests effective alternatives appearto be much more limited. Regarding the assertionthatthe current 14 day retreatment interval is too restrictive, it is not clear to BEAD why growers cannotuse one ofthe available alternatives ifpestpressure is particularly high in cases where they cannot wait 14 days to control pests. Regarding the issue of "untreated" buffers that may berequired for dicrotophos applications, BEAD capnot find a reason why suchbuffers could not be treated with alternatives to dicrotophos, assuming thattheir labels remain unchanged inthis context. Therefore, it is not clear why such buffers would
. create an insurmountable problem, at least interms ofstopping the inward spread ofmigrating stinkbugs and plantbugs. That said, BEAD agrees that such a combination strategy (i.e., treatment ofbuffers with alternatives plus dicrotophos treatment within fields) would increase overall pesticide usage on a given cotton field (and increase production costs to an unknown extent)
. 

### Comments from AMVAC (registrantfor dicrotophos)

• Information onpestpressure and control strategies, withthe following main points, was provided: For plantbug management, growers use 8-10 applications (ofall insecticides, including butnot limited to dicrotophos) in a growing season. Ofthese, key active ingredients used in resistance management rotation are thiamethoxam, imidacloprid, acephate, oxamyl, sulfoxaflor, and pyrethroids. Dicrotophos is applied after first bloom, in rotation after neonicotinoid insecticides are used. Itis sometimes applied in the late season whenthere are mixed populations ofplant and stinkbugs. For stink bug management,**growe s**  use 4-6 applications ofinsecticide in a growing season. Common active ingredients used are dicrotophos, acephate, pyrethroids, Page 3 of5and neonicotinoids. Three stink bugs occur in cotton
- green, southern green, and brown. Dicrotophos works on all stink bugs, but is most effective againstbrown stink bugs.

• Information on dicrotophos application parameters with the following mainpoints, was also provided: For early season use (emergence to pre-bloom)-one application for thrips or leafhoppers is typical. For late season use (first bloom to 30 days prior to harvest

- Early season use cost is $4.50/A for dicrotophos compared to $12/A for acetamiprid. Use ofacephate in lieu ofdicrotophos triggers spider mites and cotton aphids. A broad assertionthat dicrotophos is "essential" for late season use was made.

• Information on aerial application and buffers withthe following mainpoints, was also provided: Aerial applicatio!l is critical for early and late season application. Wet field conditions prevent ground applications, particularly in the mid-South and Southeast. Growers rely on aerial application when weather is wet. AMVAC opposes buffers. Untreated areas**~ound** fields is not acceptable IPM practice, and gives peststhe opportunity to reinfect the field.
• Information onretreatmentinterval was also provided:
· Current 14 day retreatment interval allows growers flexibility while still limiting environmental impact. Furtherrestrictions on the retreatment interval would increase use ofother active ingredients and result in more harm to pollinators. BEAD Response BEAD appreciates the general information op. cotton pest management. BEAD has already pointed out the importance ofdicrotophos as a control option where plant and stink bugs are involved (Mallampalli etal. 2014). Where thrips are a majorpest, however, itis not clear to BEAD (from this comment) why growers could not use several other alternatives shown in use byproprietary data and recommended by several cotton production guides (e.g, MSU 2015, VGA 2014). These include acephate, aldicarb, imidacloprid, dimethoate, and spinetoram. In its 2014 memorandum, BEAD noted the value ofdicrotophos as one plant and stinkbug control option, and discussed the recent usage and recominendations ofsome other insecticides for the same purposes, many ofwhich were mentioned inthe comment summarized above. However, BEAD did not see any discussion in the comment ofthe impact onyield or production costs ifdicrotophos use was replaced withthese alternatives. Without such information, BEAD must stand by its qualitative conclusion (Mallampalli etal. 2014) that dicrotophos is an occasionaUy important component ofcotton pest managementprograms. Regarding the importance ofaerial application, BEAD acknowledges thatthis treatment method appears to be moreprevalent in mid-Southern cotton. This is supported by recent proprietary usage survey data. However, on a national scale, the vastmajority ofdicrotophos applications (over 80 

### % for the years 2008-2012) are made by ground-based equipment,

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indicating that the majority ofcotton growers in the country are usually able to apply dicrotophos this way. Regarding the tendency ofacephate to cause outbreaks ofmite and aphid pests, BEAD acknowledges thatthis insecticide has been described as increasing spider mite populations in hot, dry weather conditions (e.g., Reissig 2014). However, this effect can occur with other widely used cotton insecticides, such as neonicotinoids and some pyrethroids (MSU 2015, Smith 

### et al. 2013). BEAD is unaware ofresearch documenting a similarimpact on cotton aphid populations and would consider any such information submitted by the commenter. BEAD is also unable to substantively evaluate the impact ofsuch effects from acephate as a dicrotophos alternative, based onthe content ofthe comment. The issue of"untreated" buffers has been addressed in BEAD's response to the previous comment (above). 

### REFERENCES Mallampalli, N, J. Becker, and D. Atwood. 2014. Information to support registration review of dicrotophos: cotton crop phenology in the southern U.S., recent dicrotophos use patterns; andpotential alternative insecticides. Available at www.regulations.gov in docket EPAHQ-OPP-2008-0440. MSU. 2015. Insect Control Guide for Agronomic Crops. Available from Mississippi State University onthe web at http://msucares.com/insects/cotton/index.html. [Accessed June 2015]. Reissig, D. 2014. Alternatives to Acephate for Thrips and Dealing with Lackluster Management. Available onthe web at http://cotton.ces.ncsu.edu/2014/05/alternatives-to-acephate-forthrips-and-dealing-with-lackluster-management/ [Accessed June 2015]. Smith, J.F., A.L. Catchot, F.R. Musser, and J. Gore. 2013. Effects ofaldicarb and neonicotinoid seed treatments ontwospotted spider mite on cotton. J. Econ. Entomol. 106(2): 807-815. UGA. 2014. Cotton Production Guide. Publication# CSS-14-01 ofthe University ofGeorgia College ofAgricultural and Environmental Sciences Cooperative Extension. Available on the web at www.ugacotton.com. [Accessed June 2015].

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