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Mancozeb - NYS Denial of SLN Application for use of Dithane DF for Control of Late Blight on Potatoes 5/94

May 31 1994
Mr. James D. Davis
Agricultural Chemicals Registration
and Regulatory Affairs Department
Rohm and Haas Company
Independence Mall West
Philadelphia, PA 19105
Dear Mr. Davis:
   Re:   Application for a Special Local Need Registration in
         New York State, Under FIFRA Section 24 (c), of the
         Pesticide Product Dithane DF Agricultural Fungicide
         (EPA Reg. No. 707-180)
     The Department has reviewed your Section 24(c) (Special Local Need)
Registration application, received March 2, 1994, and additional
information, received May 5, 1994, in response to our letter dated April
12, 1994 (copy enclosed). The registration would allow an increase in the
amount of Dithane DF Agricultural Fungicide used on potatoes per acre per
season from a current label maximum of 10.5 lbs. of active ingredient
(mancozeb) to 15 lbs. of active ingredient. The increased rate would
possibly control metalaxyl (Ridomil) resistant strains of late blight on
New York potatoes.
     The Department has determined that the information submitted does not
adequately justify the higher per season use rate and the higher
associated risk. The possible benefits associated with the increased rate
does not outweigh the risks involved. The EPA has numerous concerns about
mancozeb and EBDC's (ethylene bisdithiocarbamates) and carcinogenic,
developmental, and thyroid effects caused by ETU. Ethylenethiourea (ETU)
is a common contaminant, metabolite and degradation product of EBDC's.
     The Department feels that if the currently registered label for
Dithane DF Agricultural Fungicide (EPA Reg. No. 707-180) is followed
exactly, the amount of mancozeb allowed should be sufficient to achieve
control.
     The current label states that the product is to be applied at a rate
of 0.75 to 1.5 lbs. of mancozeb per acre and not to exceed a total of 10.5
lbs. of mancozeb per acre. Application of the product is to begin when the
plants are 4 to 6 inches high and the lowest rate is to be used. The rate
should be increased to 1.0 to 1.5 lbs. of mancozeb per acre as the vines
increase in size. The label also recommends that the product should be
used within an Integrated Pest Management Program and that vine kill
should occur 14 days before harvest.
     The support letter for this SLN request, from Dr. Rosemary Loria of
Cornell University, Department of Plant Pathology (copy enclosed), states
that the increase sought by the SLN would allow for 10 applications at 1.5
lbs. of mancozeb per acre. The request implies that the current label will
not be followed and that the maximum application rate will be used from
the first application, rather than starting at the lowest rate and
gradually increasing to the maximum rate.
     It should be noted that chlorothalonil is also effective on metalaxyl
resistant strains of late blight. Therefore, an alternative to increased
mancozeb rates exists.
     Based on the above information, the Department proposes to deny your
application for a Special Local Need registration. This denial will be
effective thirty days from the receipt of this
     During the thirty day period following receipt of this letter you may
pursue the options available under Article 33-0711 of the New York State
Environmental Conservation Law.
Please call Ms. Maureen Serafini, of my staff, at (518) 457-7446, if you
have any questions.
Sincerely,
                                 Robert J. Haggerty, Jr.
                                 Chief
                                 Bureau of Technical Support
                                 Division of Hazardous Substances
                                   Regulation