Dow AgroSciences Prohibits Residential Use of Clopyralid in California

INDIANAPOLIS – On March 28, the California Department of Pesticide Regulation (DPR) took action against 15 herbicide products containing the Dow AgroSciences-manufactured herbicide clopyralid, based on reports of harmful effects to residential lawns when contained in compost material.

In response to the DPR announcement, Dow AgroSciences and Riverdale Chemical Company announced today that they have notified the U.S. Environmental Protection Agency (EPA) of product label changes, prohibiting the herbicide’s future use on California residential properties.

The actions result directly from reports claiming that small levels of clopyralid in compost may damage sensitive plants, such as tomatoes, peas, beans and sunflowers. According to an April 11 Dow AgroSciences press release, the company developed the label changes as a precaution and a means to cooperate with the DPR, even though the company is not aware of documented instances of plant damage and the reports may have resulted from misuse.

Riverdale Chemical Company joined Dow AgroSciences in the EPA notification because Riverdale also manufactures herbicide products that contain clopyralid.

 In addition, both Dow AgroSciences and Riverdale have asked lawn care operators, dealers and distributors to cease selling or using clopyralid-containing products on California residential lawns.

Although DowAgroSciences herbicides with clopyralid currently have label restrictions against composting grass clippings that have been treated with the product, residential customers may or may not be aware of the possible harm clopyralid can cause to sensitive plants. Therefore, the new label restrictions ensure that homeowners won’t prepare compost with clopyralid-treated grass clippings.

Restrictions will apply strictly to California because of the frequency of composting and curbside recycling of grass clippings, noted Garry Hamlin, spokesman, Dow AgroSciences, Indianapolis, Ind. “These are unique conditions that apply to California because of its widespread and aggressive composting,” he said. “So, it’s a situation that is not necessarily common.”

Further, since composting primarily takes place on a residential basis, the restrictions will not apply to commercial properties. “It’s not necessary to stop using clopyralid on properties that will not have composting,” he related.

Cancellation notices have been sent to seven registrants that market clopyralid products, including The Andersons, Howard Johnson’s, Lebanon Chemical, LESCO and Monterey Chemical, in addition to Dow AgroSciences and Riverdale. Although notification has been sent to the EPA for the label changes, it’s not clear when the revisions will take effect, Hamlin stated.

According to the Dow AgroSciences press release, clopyralid has been on the market for 15 years and is used by farmers, foresters, ranchers, golf course managers, recreation professionals and others to control invasive weeds. The product has been registered in California since 1997.

The author is Assistant Editor – Internet of Lawn & Landscape magazine.