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Quinoxyfen
NYS DEC Letter - Specific Exemption Request for Use on Non-Edible-Peel Cucurbits 4/04

New York State Department of Environmental Conservation
Division of Solid & Hazardous Materials

Bureau of Pesticides Management
Pesticide Product Registration Section
625 Broadway, Albany, New York 12233-7257
Phone 518-402-8768     FAX 518-402-9024
Website: http://www.dec.state.ny.us/website/dshm/pesticid/pesticid.htm
E-Mail: ppr@gw.dec.state.ny.us

April 27, 2004

Mr. Dan Rosenblatt
Team Leader
USEPA/Office of Pesticide Programs
Emergency Response Team (7505C)
Document Processing Desk
Crystal Mall 2--2nd Floor
1921 Jefferson Davis Hwy.
Arlington, Virginia 22202

Dear Mr. Rosenblatt:

Re: Specific Exemption Request for Use of Quinoxyfen (Quintec, EPA Reg. No. 62719-375) to control powdery mildew (Podosphaera xanthii) on melons, winter squash, gourds, and pumpkin (non-edible-peel curcurbits) in New York State during the 2004 growing season

    The New York State Department of Environmental Conservation, as the State lead agency for pesticide matters, hereby requests approval of the referenced application (see enclosure) under Section 18 of the Federal Insecticide, Fungicide and Rodenticide Act, as amended. The enclosed application includes the information required in 40 CFR, Part 166, Subpart B (166.20).

    Powdery mildew is capable of long-distance wind dispersal and it may be capable of overwintering in the soil or on alternate hosts. It is essential to suppress development of the pathogen on the undersides of leaves as well as on upper surfaces because conditions are more favorable for the pathogen on the undersides. It is difficult to deliver spray material to the undersides of curcurbit leaves, because of the dense canopy. Fungicides with systemic or translaminar activity have been the only option for effectively controlling powdery mildew (Appendix 2).

    Contact protectant fungicides, such as Chlorothalonil, Sulfur and Oil are effective against powdery mildew where they are deposited, almost exclusively on the upper surfaces of curcurbit leaves. These products have shown limited control on the undersides of the leaves, but are not as effective as the systemic fungicides. Systemic fungicides are highly effective in control of this pathogen, when they are not compromised by occurrence of resistant pathogen strains. These systemic fungicides include the stobilurins (QoI), Topsin and demethylation inhibitor (DMI) fungicides. Occurrence of resistance and its impact on control has been documented through research conducted since 1990 (see Appendix 3).

    Fungicide efficacy experiments have shown quinoxyfen to provide excellent control of powdery mildew on lower surfaces of leaves as well as on upper surfaces (Appendix 4). Control has been excellent even where fungicide resistence has affected efficacy of Qol fungicides. Quinoxyfen (Quintec) has a novel mode of action, affecting G-proteins in early cell signaling. There is no cross resistance with other fungicides. Excellent control achieved on the underside of leaves is thought to be due to redistribution via its vapor phase.

    A maximum of three foliar applications of Quintec, none applied consecutively, per crop is requested. Quintec should be applied on a ten- to 14-day application interval in combination and alternation with other effective fungicides at their recommended rates and spray intervals. The first application should be made either preventively or shortly after detecting powdery mildew at the action threshold of at least one of 50 old leaves with symptoms. The recommended rate is 4.0 oz of Quintec/acre/application (1.05 oz. ai/acre/application). It is estimated that all of the 11,300 acres of non-edible-peel curcurbits may be treated. The maximum anticipated use of Quintec is 1,075 gallons of product or 1,490 lb. of active ingredient. All applicable restrictions currently on the label would apply. A PHI of three days is requested.

    The registrant, Dow Agrosciences, supports this request to use Quintec (EPA Reg. No. 62719-375) for control of powdery mildew on non-edible-peel curcurbits. Quintec is currently registered by USEPA for use on grapes, hops and cherries. Quinoxyfen was identified as an IR-4 registration priority.

    The anticipated use season for quinoxyfen on non-edible-peel curcurbits in New York State is from July 1, 2004 through September 30, 2004. Therefore, your attention to this request is appreciated.

    Three copies of this application are enclosed per the February 9, 2000 letter. Please contact Robin Hackett, of our Pesticide Product Registration Section, at (518) 402-8768, if you require further assistance on this request.

Sincerely,

Maureen P. Serafini
Director
Bureau of Pesticides Management

Enclosures
cc: w/enc. - A. Enache, USEPA Region II
cc: w/o enc. - G. Good\W. Smith, Cornell University, PMEP
R. Zimmerman\R. Mungari, New York State Dept. Of Ag. & Mkts.