Stop the Killer Compost

Call it “Attack of the Killer Compost.” Something is wilting tomatoes, squeezing the life out of them like ketchup bottles at an all-night diner.

Will Hollywood bite? More important, will the California Integrated Waste Management Board? The real-life version that tops the marquee at the board’s meeting Wednesday is, if not scarier, certainly more serious.

Compost samples in San Diego and, most recently, Los Angeles have tested positive for traces of clopyralid, a weed killer ingredient that also kills or stunts tomatoes, potatoes, sunflowers and certain other garden goodies. Unlike many other herbicides, clopyralid survives the high temperatures that turn grass clippings and other plant debris into soil-like compost. Compost made from clopyralid-treated clippings could kill gardeners’ crops--and the market for recycled green waste.

Only a few compost samples have tested positive in California so far. No plants are known to have been inadvertently killed, as happened in Washington state. By acting now California can still prevent contamination. But act it must, given the approach of Southern California’s high mowing season and clopyralid’s popularity with lawn care companies.

Recycling green waste is a big deal in California because it reduces the amount of garbage sent to landfills. Ten years ago Sacramento began requiring cities and counties to divert 50% of their waste from landfills or face fines as high as $10,000 a day. Los Angeles diverts 55%, much of that through curbside collection of 2,000 tons of yard clippings a day, which trucks take to city composting centers.

Aware of the rising alarm, clopyralid’s manufacturer, Dow AgroSciences, is researching ways to speed the chemical’s breakdown in composting. Until Dow has results, the waste board should urge the state Department of Pesticides to follow Washington state’s lead in issuing emergency regulations banning the use of herbicides containing clopyralid on residential and commercial lawns and golf courses. Homeowners should check the ingredients in their garden care products, and businesses should ask their lawn care companies not to use the chemical. Dozens of products contain clopyralid, including Confront, Battleship, Chaser Ultra, Millennium Ultra, Momentum, ProScape and Strike Three Ultra.

Before allowing new herbicides on the market, the U.S. Environmental Protection Agency should conduct tests to confirm that the products break down before they can cause toxic contamination problems in compost.