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
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
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
Norman H. Nosenchuck, P.E.
Division of Solid & Hazardous Materials
cc: w/enc. - D. Rutz/W. Smith, Cornell University
N. Rudgers, NYS Dept. of Ag. & Mkts.
N. Kim/A. Grey, NYS Dept. of Health