Information Requests Monitoring System

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Request ID: 145
Request From: Steve Toth
Date Requested: Mar 03, 2006
Request: Note the following request for feedback on proposed EPA risk mitigation measures for dimethoate use on a number of crops (see below) from the USDA's Office of Pest Management Policy. They need a response "on the week of March 6" (i.e., next week). Please circulate among the specialists in your state/territory and send any responses to the Southern Region IPM Center Information Requests Monitoring System no later than next Friday, March 10. Thanks. Steve Toth ------------------------------------------------ EPA has proposed risk mitigation measures for a number of crops. EPA is proposing that the numbers of applications be reduced to bring down calculated drinking water risks. Your additional feedback is needed if you wish to retain two applications for the following crops: Please bear in mind that I will forward your response directly to EPA who desires documentation of USDA feedback . Cotton, field/pop corn, and wheat, citrus, pears, alfalfa, safflower, pecans, peppers, and grass seed. Efforts are already underway to retain two applications for cherries and succulent peas. If you need two applications, is one an early application and the second a late season application? (Drinking water assessments are significantly improved if any two applications are far apart in time ) Aerial applications result in greater drinking water risk than ground applications. EPA is now assuming: cotton - two applications, 14 days apart field/pop corn - two applications, 7 days apart Wheat - two applications, 5 days apart citrus - two applications 31 days apart (IS dimethoate applied aerially for citrus?) alfalfa (seed and hay) - only one application safflower - two applications, 14 days apart Pecans - only one application (Is dimethoate applied aerially for pecans?) Peppers - only one application ( Is dimethoate applied aerially for peppers?) Grass Seed - 0.5 lb a.i./Acre (Is dimethoate applied aerially for grass for seed?) Also, if the applications are not rainy season, then run-off is significantly reduced as well. EPA wishes to complete is final decisions on dimethoate so your feedback the week of March 6 would be optimal. Many Thanks, Teung Please do not hesitate to contact me if you have any questions or comments. Best regards, Teung Soybean Rust Info http://www.usda.gov/soybeanrust/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Teung F. Chin, Ph.D. Biological Scientist Office of Pest Management Policy Agricultural Research Service United States Department of Agriculture LOCATED AT: USDA Animal & Plant Health Inspection Service 4700 River Road, Unit 149 (Room 3D-06.8) Riverdale, MD 20737-1237 Phone (301) 734-8943 Fax (301) 734-5992 Teung.F.Chin@usda.gov http://www.ars.usda.gov/opmp ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ----- Forwarded by Teung F Chin/MD/APHIS/USDA on 03/03/2006 01:24 PM ----- @inter2@gw To 03/02/2006 10:33AM Teung F Chin/MD/APHIS/USDA@USDA Subject FW: Dimethoate: USDA Crop Profiles on wheat, cotton, and corn... Hi Teung Currently, EPA is proposing to allow only 1 application of dimethoate per year on cotton, field/pop corn, and wheat. I have reviewed the USDA crop profiles for each state for which they are available (see attached). Based on my review, it appears that 2 applications per year are needed on these crops. My rationale is that dimethoate is one of a very few systemic insecticides available, it is used on several pests on these crops, the timing of infestation of these pests can either be in the early stages of growth and/or later in the growth cycle. So, in it is important that dimethoate be an available option for growers later in the growing season even if an early season application is made. Is there a way that you can check with growers of these crops to see if they support the above rationale? And if they do, will they provide an e-mail or letter to EPA indicating so? Note also that EPA is also proposing to keep only 1 application for cherries, citrus, pears, alfalfa (although I've asked if they mean 1/cutting), succulent peas, safflower, pecans, peppers, and grass seed. For many of the same reasons given for cotton, corn and wheat, I suspect that 2 applications are also needed on these crops. I know from talking to the Cherry growers in the Pacific NW that they may need 1 application early season and 1 application after harvest in the fall. Do you think the grower contacts that you have will be willing to provide support for 2 applications per year on these crops? Regards, Paul

Responses
Responder: Henry Fadamiro
State: AL
Date Requested: Mar 05, 2006
Response: Dimethoate is worth keeping on wheat and alfalfa for three reasons: 1) it is still a good aphid material. 2) It has some systemic activity. 3) Most importantly it is not a restricted use material. All other aphid materials are restricted use. Occasionally mites are a problem on corn, and this is the only miticide that is not restricted. I would vote to keep it on wheat, corn, and alfalfa.

Responder: Scott Stewart
State: TN
Date Requested: Mar 06, 2006
Response: As an extension employee, I have primary responsibility for insecticide recommendations in field crops. Thus, my responses on confined to these areas. We still have dimethoate in our cotton recommendations for the following: 1) Thrips and aphids (@0.125 - 0.25 lb ai/a). 2) Plant bugs (@0.25 lb ai/a)and stink bugs. Pretty good as a tank-mix partner with pyrethroids in mid to late season. 3) Spider mites (@ 0.25 lb ai/a). This often provides suppression of late-season mite populations. Two applications at a 4-5 day are sometimes critical to get satisfactory control. In corn and wheat (in Tennessee), the primary use of this product would be aphid control, and it works well because of its systemic activity. A fair compromise for cotton would be "a maximum of two applications not to exceed 0.75 lb ai/a during a single season." In wheat or field corn, I would suggest that two applications not to exceed 0.5 lb ai/year would allow sufficient use. Thus, allowing a single application at a high rate or two applications at a low rate. Dimethoate is a utility product, and because of the low cost and systemic action, it definitely has a niche. However, it would be unusual for us to need more than the amounts suggested above. Dr. Scott Stewart IPM Specialist UT Extension (731) 425-4709 sdstewart@utk.edu

Responder: Darrell Hensley
State: KY
Date Requested: Mar 06, 2006
Response: Darrell, Dimethoate is not used mcuh at all in vegetable production in KY and further restrictions would not hurt our industry as there are effective alternatives. Ric Rbessin@uky.edu

Responder: Darrell Hensley
State: KY
Date Requested: Mar 06, 2006
Response: Darrell: Our interest is in retaining dimoethoate on soybean. I doubt that there is much if any used on the other grain commodities. I will let Ric respond if necessary on fruit / veg. Lee Townsend is out right now for health reasons, but in my experience little of this is used on alfalfa either. Doug Johnson doug.johnson@uky.edu

Responder: Kerry Siders
State: TX
Date Requested: Mar 06, 2006
Response:

Responder: Mark Mossler
State: PR
Date Requested: Mar 09, 2006
Not Important/Relevant to my state(s)
Response:

Responder: Mark Mossler
State: VI
Date Requested: Mar 09, 2006
Not Important/Relevant to my state(s)
Response:

Responder: Mark Mossler
State: FL
Date Requested: Mar 09, 2006
Response: The three areas of interest for dimethoate users in FL include citrus, pecan, and bell pepper. The production systems for these crops are under intensive IPM, which generally precludes the use of dimethoate. It is used rarely in pepper, citrus, or pecan, and it would generally be spot applied (i.e., not aerially) in these cases. Extension personnel did not object to the proposed restrictions presented in the email message.

Responder: Charles Luper
State: OK
Date Requested: Mar 09, 2006
Response: Please note the information from our Specialists below. Also the crop profile document put out incorrectly stated that Oklahoma did not include dimethoate in our wheat crop profile. Dimethoate is listed in our Wheat crop profile. Charles, I have revised the crop profile information on dimethoate to reflect what it can be used for in Oklahoma. I want it to be available for two applications. Tom A Royer Extension Entomologist Department of Entomology & Plant Pathology Oklahoma: Dimethoate is used to control aphids, winter grain mite, brown wheat mite and grasshoppers in Oklahoma. Aphids, primarily the greenbug, are a sporadic problem, but in some years can cover large acreages, especially in fall through early spring during dry winters. Grasshoppers are generally a problem in seedling wheat in fall. The winter grain mite is treated in fall and winter, and the brown wheat mite is a problem during dry springs. Charles, I do believe our best approach is to retain a two application per season level. In alfalfa there are basically two times in the year when dimethoate use may be critical, the first is during the spring season of growth when pea, blue and cowpea aphids can have a sudden and profound impact on the crop. Currently, only dimethoate and lorsban provide good to excellent aphid control and while other materials are available (synthetic pyrethroids) many, by their own admission on the label, describe their inherent shortcomings related to aphid control. In addition, dimethoate has shown some capacity for foliar uptake and systemic ability on alfalfa. In addition to these concerns, in the fall season, under dry conditions like we experienced in 2005, seedling stands can be quickly devastated by spotted alfalfa aphids. These insects can also affect established stands. This pest and blue alfalfa aphids, represent two major aphid pests that threaten Oklahoma alfalfa production nearly every year. To further compound this problem, the number of insecticides available for controlling these organisms continues to narrow and the only viable substitutions lately have been synthetic pyrethroids. These latter chemicals have an established history of problems with resistance, particularly for those pests with large populations that cycle through their life cycles and generations quickly. In pecan, we have a similar situation, where either synthetic pyrethroids or neonicotinoids are the primary means of controlling aphid outbreaks. While these materials will provide some level of control they both have inherent problems associated with resistance in these aphid populations. Once again, conditions experienced in 2005 taught us some valuable lessons related to this matter and illuminated how environmental conditions can quickly favor pest outbreaks, even in the midst of regular control. Many growers who routinely apply 2-3 treatments for pecan weevil in 2005 quickly realized a dramatic resurgence in aphid populations that we have not experienced in several years. Without the flexibility of multiple tools in our arsenal, management of these insects may become an issue in the future. Phil Mulder OSU Extension Entomologist

Responder: Jack Bacheler
State: NC
Date Requested: Mar 10, 2006
Response: Dimethoate is not presently recommended on cotton in North Carolina. Jack Bacheler Extension Entomologist (Cotton) Department of Entomology North Carolina State University

Responder: John Van Duyn
State: NC
Date Requested: Mar 10, 2006
Response: We list dimethoate as an alternative for aphid control in sorghum and wheat in the North Carolina Agricultural Chemicals Manual. There are alternatives in both cases but the loss of dimethoate brings to mind questions about the sustainability of these alternatives. Most are phosphates that may fall to the EPA axe; e.g. disyston EC, Penncap-M, and Lorsban 4EC (on one or both crops each). Warrior is listed for both crops but it is a pyrethroid, a class used on all crops and with a history of causing aphid resistance, at least in cotton. I am for keeping this old chemistry, due to it's relative safety vs others and as a matter of a resistance management option. Thanks. John Van Duyn Extension Entomologist Department of Entomology North Carolina State University

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