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Registration of Mefenoxam 9/96

New York State Department of Environmental Conservation
Division of Solid & Hazardous Materials
50 Wolf Road, Albany, New York 12233-7250
Phone 518-457-6934 FAX 518-457-0629

SEP 24, 1996
Mr. Jerry Harrison
Manager State Registrations
Ciba-Geigy Corporation
P. O. Box 18300
Greensboro, NC  27419

Dear Mr. Harrison:

Re:  Registration of the New Active Ingredient - Mefenoxam Contained in 
the Pesticide Products Ridomil Gold EC (EPA Reg. No. 100-801), Ridomil 
Gold WSP (EPA Reg. No. 100-802), Ridomil Gold Bravo (EPA Reg. No. 100-
801, 50534-188), Ridomil Gold PC (EPA Reg No. 100-792), Ridomil Gold GR 
(EPA Reg. No. 100-798), Ridomil Gold MZ (EPA Reg. No. 100-803); and for 
Apron XL LS Fungicide (EPA Reg. No. 100-799)

The New York State Department of Environmental Conservation (NYSDEC) has 
accepted your application for the registration of the new active 
ingredient, Mefenoxam, contained in the pesticide products Ridomil Gold 
EC (EPA Reg. No. 100-801), Ridomil Gold WSP (EPA Reg. No. 100-802), 
Ridomil Gold Bravo (EPA Reg. No. 100-801, 50534-188), Ridomil Gold PC 
(EPA Reg No. 100-792), Ridomil Gold GR (EPA Reg. No. 100-798), Ridomil 
Gold MZ (EPA Reg. No. 100-803); and on September 4, 1996 for Apron XL LS 
Fungicide (EPA Reg. No. 100-799).  The Ridomil Gold and Apron products 
are labeled to control specific fungal diseases on a wide variety of 
fruits, vegetables, nuts, grain, cotton, tobacco and grasses.  Staff 
combined their review of these products in the interest of efficiency.

The active ingredient mefenoxam [(R)-2-[(2,6-dimethylphenyl)-
methoxyacetyl-amino]-propionic acid methyl ester and related compounds] 
is primarily the R enantiomer of the currently registered compound 
metalaxyl, which contains both R and S enantiomers in equal proportions. 
This application was handled as a New Active Ingredient application 
rather than as a Major Change in Labeling because the new product was 
assigned a new EPA registration number by the United States 
Environmental Protection Agency (EPA).

A condition of federal registration for the Ridomil Gold and Apron 
products requires the registrant to cancel the registration of metalaxyl 
and its end use products.  However, the EPA's final decision on 
cancellation has not been announced in the Federal Register. If the 
metalaxyl registrations are canceled, the Federal Register states that 
EPA will allow sale and use of metalaxyl-containing products until 
December 31, 1998.

The data package for this product was reviewed by the Division of Fish, 
Wildlife, & Marine Resources (DFW&MR); our Technical Support & 
Laboratory Services Section (TS&LS); and the New York State Department 
of Health (NYSDOH).


The DFW&MR Bureau of Environmental Protection (BEP) in their review did 
not object to registration.  The Ridomil Gold products contain between 
0.48 to 46.6% mefenoxam.  Apron contains 32.23%. Ridomil is applied at a 
rate of 2 lbs ai/acre, with a maximum application of 6 Ibs. ai/acre/ 
season.  Apron is applied at a rate of 0.0308 lbs. ai/100 lbs. of seed 
for sweet corn, peas, sorghum, sunflowers, and turfgrass.  With a 
seeding rate of 120 lbs. seed/acre, sorghum contains 0.37 lbs. of 
mefenoxam per acre.

According to aquatic and terrestrial models, mefenoxam is not toxic to 
fish, birds,aquatic invertebrates, or aquatic plants on an acute basis. 
Toxicity thresholds areexceeded for birds feeding long term on short 
grass with mefenoxam residues, and for small mammals feeding short and 
long term on short grass containing these residues.

The maximum application rates used are for avocadoes, which are not 
grown in New York State.  The application rates for crops grown in this 
State are lower, and would not exceed toxicity thresholds.  Mefenoxam, 
also, has a field dissipation half-life of 35 days and would not be 
chronically toxic to mammals or birds.  Therefore, the pesticide
products containing mefenoxam cited in this review will not adversely 
impact the fish and wildlife resources of New York State.

The New York State Department of Health stated in their review that the 
toxicity of mefenoxam is similar to that of metalaxyl.  These compounds 
are not highly toxic and the estimated dietary exposure from metalaxyl 
use does not pose sign)ficant health risks.  The reduced application 
rate of the Ridomil Gold products compared to the metalaxyl products is 
likely to result in even less dietary exposure as well as reduced worker 
risks and environmental loading.

There are no chemical-specific federal or State drinking 
water/groundwater standards for mefenoxam.  Based on its chemical 
structure, mefenoxam falls under the 50 microgram per liter general New 
York State drinking water standard for an "unspecified organic 
contaminant" (6NYCRR Part 5 - Public Water Systems).

The TS&LS Section stated in their review that they did not object to the
registration of the listed Ridomil Gold products and that they had no 
objection to registration of Apron XL LS Fungicide as a seed treatment 
in New York State.

The new active ingredient, mefenoxam, contains a higher ratio of the "R"
enantiomer of metalaxyl, the active ingredient in a product line which 
Ciba has marketed for over 15 years under the trademark Ridomil. 
Metalaxyl is composed of equal amounts of the two enantiomers described 
as "R" and "S" enantiomers.  Ciba has been successful in separating the 
two enantiomers and demonstrating that the "R" enantiomer is more active 
in controlling plant diseases than either the "S" enantiomer or the 
combination of the two.

 Since these new Ridomil Gold and Apron products contain primarily the 
"R" enantiomeric form of metalaxyl, they can be applied at lower rates 
without loss of disease control.  The net result is reduced amounts of 
product being applied to the environment.  These products have all the 
favorable characteristics of the Ridomil products but will be used at 
one-half the rate for current Ridomil products.

Because of the net reduction of impact to the environment from the new 
products, EPA has designated the Ridomil Gold products as "reduced risk" 
materials.  Some of the studies are not required for reduced risk 
materials, and EPA Data Evaluation Reviews were not produced by EPA for 
those studies that were performed.  The following data was taken from 
Ciba-Geigy's summaries of the studies performed as part of the
environmental fate review:

Mefenoxam solubility is 26 g/L; the average aerobic metabolism half-life 
is 58.4 days; the soil photolysis half-life was 358 days; the koc's 
ranged from 20 to 790 in a sand and from 1299 to 3539 in a silty clay 
loam; and the column leaching studies ranged from low in a silty clay 
loam, to high in a sand and in a sandy loam.

While these parameters indicate that this is a fairly persistent, mobile 
compound, it has been projected that up to 50% less impact to the 
environment will occur using these new products.  Because of this 
benefit to the environment, the TS&LS has no objections to the 
registration of these six products.

The major new use pattern in Apron XL LS (EPA Reg. No. 100-799) is as a 
seed treatment for control of pythium and phythophthora causing damping-
off, seed rot, and systemic downy mildew diseases of certain crops.  The 
seed treatment use pattern did not require additional review; therefore, 
the TS&LS has no objection to the registration of Apron XL LS.

After consideration of the reviews by NYSDOH, DFW&MR, and by TS&LS, the 
Department accepts for registration Ridomil Gold EC (EPA Reg. No. 100-
801), Ridomil Gold WSP (EPA Reg. No. 100-802), Ridomil Gold Bravo (EPA 
Reg. No. 100-801, 50534- 188), Ridomil Gold PC (EPA Reg No. 100-792), 
Ridomil Gold GR (EPA Reg. No. 100-798), Ridomil Gold MZ (EPA Reg. No. 
100-803); and for Apron XL LS Fungicide (EPA Reg. No. 100-799) for use 
as labeled to control specific fungal diseases on a wide variety of 
fruits, vegetables, nuts, grain, cotton, tobacco and grasses in New York 
State.

Enclosed for your records are the stamped-accepted label and the 
certificate of registration for the above product.

If you have any questions on this matter, please contact Maureen 
Serafini, Supervisor of our Pesticide Product Registration Section, at 
(518) 457-7446.

Sincerely,




Norman H. Nosenchuck, P.E.
Director
Division of Solid & Hazardous Materials

Enclosures
cc: w/enc. - D. Rutz/W. Smith, Cornell University
             N. Rudgers, NYS Dept. of Ag. & Mkts.
             N. Kim/A. Grey, NYS Dept. of Health