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Special Use Permit Proposed for Controversial Herbicide in Wisconsin
(April 11, 2003)
Wisconsin Department of Agriculture officials are proposing a "special local need" exemption to allow cranberry growers to use the controversial, persistent herbicide clopyralid, produced by Dow AgroSciences. The chemical has been tied to plant damage at miniscule levels when found in compost material. Growers need the exemption for the product Stinger because it is not registered with the U.S. Environmental Protection Agency (EPA) for use on cranberries. The exemption falls under the Federal Insecticide, Fungicide and Rodenticide (FIFRA) Section 24c, which allows states to register pesticides for additional "special local needs." The use is permitted if EPA does not respond within 60 days. The Wisconsin Department of Agriculture has allowed its use in the past under FIFRA Section 18, an "emergency use exemption." Stinger is approved by EPA for use as a weed control on other agricultural crops such as field corn, sugar beets, wheat and Christmas trees, but not registered or evaluated by the agency for its use on cranberries.

Clopyralid was banned by Washington state for use on most lawns, effective June 28, 2002, because the state found that compost material made from treated grass clippings damaged broadleaf ornamentals and vegetables grown in or around the compost. Because municipalities are encouraging composting as an alternative to filling local landfills, it is critical that the compost not cause plant damage. Washington state's regulation does allow golf courses to continue to use clopyralid, "if no grass clippings, leaves or other vegetation are removed from the site and sent to composting facilities that provide product to the public." Dow pulled the residential uses of clopyralid in California last year before the state acted. The company states on its product label that manure and foliage treated with clopyralid should not be used as a source for compost. Researchers have cited the chemical as adversely affecting the growth of tomato, eggplant, potato, spinach, clover, lettuce, pea, lentil, sunflower, pepper and bean plants at levels as low as one to ten parts per billion. A number of beneficial insects have been harmed by clopyralid, such as ladybugs and lacewings. Environmentalists cite the difficulty associated with enforcing a no composting standard and protecting ecological balance.

Environmentalists criticize FIFRA Section 24c exemptions, calling it a loophole for pesticide manufacturers to sell its product for uses without subjecting them to full review for each use. Stinger is currently being used under Section 24c in Washington, Oregon and Massachusetts, raising concerns that the need is not special or local.
Clopyralid is classified as a pyridine carboxylic acid and has the same mode of action as other growth-regulator type pesticides, including 2,4-D, dicamba, and picloram. The herbicide acts by mimicking growth stimulant hormones called auxins, causing the plant to destroy itself. Clopyralid and the products containing it are irritating to eyes, some severely. The eye hazards of four clopyralid products include permanent impairment of vision or irreversible damage. In laboratory tests, clopyralid caused what an EPA reviewer called "substantial" reproductive problems. These include a reduction in the weight of fetuses carried by rabbits who ingested clopyralid, an increase in skeletal abnormalities in these fetuses at all doses tested, and an increase in the number of fetuses with hydrocephaly, accumulation of excess fluid around the brain.

This 24c registration will allow cranberry growers to apply Stinger herbicide for broadleaf weed control, such as smartweed, clover or wild bean, in the cranberry beds. Although broadcast applications are allowed, growers will likely apply the herbicide as a spot treatment. Stinger cannot be applied by air. The preliminary environmental assessment indicates that the proposed registration will not significantly harm humans, animals, or the environment, and a full environmental impact statement is not required.

Wisconsin citizens have until April 22 to review and comment on the proposed five-year special pesticide registration. The special registration process allows states to register additional uses of pesticide products without prior federal approval, giving states flexibility to meet local needs such as controlling a plant disease or insect outbreak. For a copy of the environmental assessment, call 608-224-4546. Send comments to Ed Bergman by mail to 2811 Agriculture Dr., Madison, 2nd floor, Madison, WI 83718; or send an email to ed.bergman@datcp.state.wi.us.