Mr. Dan Rosenblatt
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
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
Maureen P. Serafini
Bureau of Pesticides Management
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.