Spokane

State extends ban on weedkiller
Potent herbicide with clopyralid can taint compost, kill certain flowers

Associated Press

OLYMPIA _ Washington will continue to ban the use of a potent herbicide on residential and commercial lawns and turf to prevent contaminating compost, the Department of Agriculture said Tuesday.

The ban on products containing clopyralid -- used to kill dandelions, clover and thistles -- took effect March 1 and originally was scheduled to remain in place for only 120 days.

The weedkiller can taint compost and kill certain flowers and vegetable plants.

In addition, effective June 28, clopyralid products to be used on cereal grains and grass used for hay may only be purchased by licensed pesticide applicators, the department said in a statement.

When clopyralid products get into compost that ends up in gardens or farms, they can kill broadleaf crops such as tomatoes and peas.

Clopyralid also can harm flowers such as asters and sunflowers.

"We are committed to resolving this problem using both rules and nonregulatory approaches," said Bob Arrington, assistant director of the state's Pesticide Management Division. "We support cooperative efforts that help the compost industry produce products that are free of clopyralid residues at levels damaging to sensitive plants."

The herbicide kills plants by imitating hormones called auxins and causing abnormal growth. During commercial composting, most chemicals used in lawn care and agriculture break down harmlessly, but clopyralid survives the process.

Department officials listened to comments from several hundred people, interest groups and members of an advisory committee.

The state is continuing the one exemption to the ban on lawn use. Golf courses are allowed to use products containing clopyralid if no grass clippings or other vegetation are then sent to composting facilities that serve the public.

Another proposal would have allowed clopyralid use on lawns at schools, parks, cemeteries and businesses. But that idea was strongly opposed in testimony at an April hearing and agriculture department officials decided not to approve it.

"People raised concerns that additional exemptions would be difficult to enforce and also would clash with goals for keeping grass clippings out of landfills," Arrington said.

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