Dow AgroSciences Discontinues Residential Clopyralid Use

The popular herbicide loses its battle against increasing regulatory concerns related to its potentially harmful effects when contained in compost.

July 25, 2002


To read past Lawn & Landscape Online stories about clopyralid, click on the links below:

  • Dow Prohibits Residential Use
    • California Department of Pesticide Regulation Begins Cancellation
      • Washington State Bans Use of Clopyralid-Containing Herbicides
        • Clopyralid Found in Compost Supplies
          • Clopyralid-Containing Herbicides Cause Controversy
              • INDIANAPOLIS, July 25, 2002 – A widely used herbicide for control of invasive, noxious and other hard-to-control weeds will no longer be used on U.S. residential lawns, as a result of an action taken to address regulatory concerns by the product’s primary manufacturer, Dow AgroSciences LLC.

                Clopyralid products will continue to be used on golf courses and certain other forms of nonresidential turf. However, Dow AgroSciences has petitioned the U.S. Environmental Protection Agency to delete residential turf uses from the clopyralid product label. Additionally, under the amended label professional applicators will now be required to notify property managers not to compost clippings from treated grass.

                Farm, ranch and forestry uses will be unaffected.

                “The decision to discontinue residential turf use of the herbicide was made to address regulatory concerns about the potential for damage to sensitive plants from clopyralid residues in compost,” said Dow AgroSciences vice president for urban pest control products Elin Miller. “This action is based on a few isolated reports of plant damage, not on concerns about human health.”

                A premium herbicide, clopyralid controls noxious and invasive weeds at very low rates. The product breaks down readily in the natural soil environment but appears to degrade more slowly in compost. 

                While herbicides containing clopyralid are only active on a few families of plants, there have been reports of residues in compost damaging sensitive plants. Few of the reported instances have been confirmed. In those cases that have been documented, primarily in Washington state, the residues were tied to programs promoting composting of grass clippings from residential lawns.

                Label directions for products from Dow AgroSciences containing the active ingredient clopyralid warn against using compost containing treated material. However, inadvertent composting of clopyralid-treated grass clippings (e.g., via curbside pickup) may be a factor in residential use.

                “We see amending the clopyralid product label to discontinue residential turf use as a prudent step while gathering data to better understand the many ways that the composting industry processes compost and the breakdown of clopyralid in these materials,” Miller said. “Considerable research is now underway that will help shed light on these issues.”

                Plant damage linked with clopyralid-containing compost seems much less likely when the compost is incorporated into soil in use. (Note: Sensitive and nonsensitive plant species lists are available at the Washington State Department of Agriculture Web site

                Products containing clopyralid have been on the U.S. market for more than 15
                years. Regulators have described the product as “a low-toxicity chemical that poses little hazard to people, animals and most vegetation.” The product is extremely effective against invasive and persistent weeds such as Yellow starthistle and Canada thistle.

                Dow AgroSciences LLC, based in Indianapolis, Indiana, USA, is a global leader in providing pest management and biotechnology products that improve the quality and quantity of the earth's food supply and contribute to the safety, health and quality of life of the world's growing population. Dow AgroSciences has approximately 6,000 people in over 50 countries dedicated to its business, and has worldwide sales of more than US $3 billion. Dow AgroSciences is a wholly-owned subsidiary of The Dow Chemical Company.