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Azoxystrobin - Registration of Heritage Fungicide 10/97

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


Mr. Michael S. O'Connor
Regulatory Product Manager
Registrations West
Zeneca Inc.
1200 South 47th Street
Richmond, CA 94804-0023

Dear Mr. O'Connor:

Re: Registration of a New Active Ingredient Azoxystrobin Contained in the Pesticide Product, Heritage Fungicide (EPA Reg. No. 10182-408)

Zeneca Inc. applied for New York State registration on March 28, 1997 for Heritage Fungicide (EPA Reg. No. 10182-408). The product contains the new active ingredient azoxystrobin. A registration decision is due by October 16, 1997.

Heritage Fungicide is a broad-spectrum fungicide applied as a foliar spray on turf which controls plant pathogens from all four major fungal groups: ascomycetes, basidiomycetes, deuteromycetes, and phycomycetes. The United States Environmental Protection Agency (USEPA) categorized azoxystrobin as a reduced-risk pesticide.

The maximum application rate is five pounds active ingredient/acre/year.

The data package submitted in support of the registration was reviewed by the New York State Department of Health (DOH) and this Department's Division of Fish, Wildlife & Marine Resources (DFW&MR) and our Technical Support & Laboratory Services Section (TS&LS).

The DFW&MR, in correspondence dated May 15, 1997, concluded that azoxystrobin is not toxic to birds or mammals. It is toxic to aquatic life. Diatoms are particularly sensitive; however, no-observed-effects concentrations (NOECs) for all aquatic species tested are less than one part per million. Azoxystrobin has the potential to be mobile in soil and could be transported off-site by runoff, but because it is used in low volume, used on turf, and has a fairly rapid field dissipation rate, runoff from treated turf is not likely to be harmful to aquatic life.

The DOH, in correspondence dated August 29, 1997, stated that neither azoxystrobin nor the Heritage product was very toxic, irritating or caused sensitization following acute exposures in laboratory animals. Azoxystrobin was also not highly toxic in chronic animal studies and did not cause developmental or oncogenic effects. Heritage Fungicide is labeled for application to sod farms and golf courses only, and exposure to the general public is expected to be minimal. The Heritage Fungicide label requires applicators and other handlers to wear a long-sleeved shirt and long pants, waterproof gloves and shoes plus socks, which should reduce exposure for these workers.

There are no chemical-specific federal or State drinking water/groundwater standards for azoxystrobin. Based on its chemical structure, azoxystrobin falls under the 50 microgram per liter (μg/L) New York State drinking water standard for "unspecified organic contaminants" (10 NYCRR Part 5 - Public Water Systems). This value of 50 μg/L should also be considered a potential State groundwater standard.

The DOH and TS&LS Section had concerns regarding the potential for groundwater/drinking water contamination by azoxystrobin degradates and use of Heritage Fungicide on Long Island. A technical meeting was held with Zeneca Inc. on September 24, 1997. Representatives of the DOH, the TS&LS Section and the Pesticide Product Registration Section attended this meeting. As a result of this technical meeting, all concerns regarding potential groundwater contamination were alleviated.

The TS&LS Section, in correspondence dated September 26, 1997, stated that the aerobic soil metabolism studies indicate a half-life ranging from 54-164 days and the photolysis study indicated a half-life of 11 days. During the field studies, azoxystrobin had a half-life of 13-20 days, with one major breakdown product, Compound 2, a microbial breakdown product. The data indicates that photolysis and microbial activity are major routes of degradation of azoxystrobin. The Koc of azoxystrobin ranges from 300 to 1690, and field studies in a variety of agronomic conditions and in turf have confirmed that the parent is immobile in soil and has little potential to leach.

Modeling, which was conducted before the September 24, 1997 meeting, showed the degradate, Compound 2, to be a potential serious groundwater problem. This modeling assumed no photodegradation and that all of the product would be washed off the foliage soon after application. Also, the soil used in the model had a pH of 8.4 and a Koc for Compound 2 of 28. The Koc is an indication of mobility in soil. A low Koc indicates high mobility. A high Koc indicates low mobility.

Several representatives of Zeneca Inc.'s environmental fate team were present at the September 24, 1997 technical meeting. They discussed the relationship of Koc to pH for the degradate, Compound 2. As pH increases, the Koc decreases. Under acidic conditions, low pH, the degradate acted much like the parent, exhibiting a higher Koc, and was much less mobile. Soil conditions of Long Island were also discussed. Typical Long Island soils are acidic, ranging from a pH of 4.5 to 5.5. The optimal pH for turf, for nutrient availability and disease management, is 6.0 to 7.0. Therefore, the pH of the top layer of soil would probably be modified on greens and tees of golf courses to be around 6.0. The underlying soil would still be more acidic.

Modeling performed after the technical meeting showed Compound 2 not to be a potential groundwater contamination concern. The modeling utilized a soil with the Koc, half-life and pH of the soil with the characteristics most like Long Island soils. The soil values used had a pH of 5.5, a Koc of 540 for azoxystrobin and a Koc of 490 for Compound 2.

The modeling also assumed that all of the product is washed off the foliage before it can significantly photodegrade. It was discussed at the technical meeting that approximately 20% of the product that is applied to the turf is absorbed within several hours and is not available to be washed off.

Therefore, assuming the worst-case scenario, and that all of the product is washed off of the turf before it can significantly photodegrade, it does not appear that it has the potential to negatively impact the surface water and groundwater in New York State. This is also due to the fact that Long Island soils tend to have pH in the range of less than 5.5.

Therefore, the Department hereby accepts for general use registration in New York State Heritage Fungicide (EPA Reg. No. 10182-408).

Enclosed are your New York State stamped "ACCEPTED" label, as submitted with no label modifications required, and a copy of the Certificate of Registration.

Please contact Maureen P. Serafini, Supervisor of our Pesticide Product Registration Section, at (518) 457-7446, if you have any questions.


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

cc: w/enc. - N. Kim/D. Luttinger - NYS Dept. of Health
N. Rudgers/ R. Mungari - NYS Dept. of Ag. & Markets
D. Rutz/W. Smith - Cornell University