Clopyralid:
When the Compost Hits the Fan

© 2002 Wendy Dager

In 1989, when actress Meryl Streep appeared on the tube to warn us of the dangers of Alar, many folks believed her.

Why not? She was a mother, she was credible, and she herself truly believed that Alar, a chemical first marketed in 1968, wasn't good for our kids. The reason Alar was so awful? After being sprayed on trees to make apples ripen longer before falling off, Alar broke down into "unsymmetrical dimethyl hydrazine," or UDMH, a byproduct shown to cause tumors in laboratory animals.

Reinforcing Streep's on-air testimony was a "60 Minutes" exposé introducing the public at large to Alar's alleged hazards. This eventually sparked a boycott of apples and apple products, and in turn, lead to apple growers' claims they had lost $100 million. Several orchards were forced into bankruptcy.

Apple growers filed a libel lawsuit, but did not win in court. Still, they were able to prove that evidence of Alar's risks was inconclusive.

Scare Tactics

Now, echoes of the Great Alar Scare are ringing in the ears of manufacturers of the herbicide clopyralid (clo-PEER-uh-lid), including Dow AgroSciences, which markets it as the product Confront™.

According to the Web site of Washington State University, which has done extensive studies on the product, "Clopyralid is a broad-leaf herbicide used to control broadleaf weeds in lawns and many agricultural crops, including turf grass and cereal grains." Clopyralid is widely used to kill clover, thistle and dandelions.

However, certain other plants, such as peas, beans, tomatoes and sunflowers, are sensitive to clopyralid.

WSU says clopyralid concentrations as low as 1 part per billion could cause these plants' demise. Because of these findings, herbicides containing the active ingredient clopyralid may not be used on lawns and turf in the state of Washington. This ban became effective March 1, 2002, for a period of 120 days. However, the Washington State Department of Agriculture has announced its intention to propose a permanent ban on most lawn and turf uses, as well as other restrictions.

But why would the state of Washington be concerned about the chemical's effects on plants that have not been treated with clopyralid?

Compost Happens

Clopyralid does not break down when composted.

According to an August 24, 2001 paper published by the U.S. Composting Council: "In several well-documented cases, compost products from clopyralid-containing feedstocks (including grass clippings, animal bedding and manures) have damaged non-target crops due to the presence of clopyralid."

Some, but not all, of the green waste that ends up in those special, environmentally-friendly trash cans is believed to have been contaminated with clopyralid prior to arriving at the compost facility.

Because clopyralid goes through the composting process with very little breakdown—including those pre-composting products which have already passed through animals—the herbicide remains an active killer even as it is mulched into the compost.

The most serious problem to date seems to be associated with Confront™, but other products are being investigated, including picloram, which is chemically similar to clopyralid.

Although the clopyralid controversy has not escalated to Alar proportions, there is industry concern that there is a rush to judgment.

Just the Facts, Jack

This was evident in a recent editorial by David G. Cassidy, editor of Turf Magazine. Turf had previously published the article "Herbicide Residues: Recent discovery threatens compost industry," and had received letters accusing the magazine of becoming "a voice for the anti-chemical, radical environmentalists."

Not true, according to Cassidy, who explained that the magazine considers it their "job to keep on top of what various governmental agencies and professional environmentalists are doing in this area."

Cassidy pointed out that clopyralid has been found in very small quantities in just a few places on the west coast (Washington state), in Pennsylvania, and in New Zealand. Worse, he said, is the other "really harmful stuff," such as salmonella and E. coli, much more commonly found in compost.

He believes the issue of clopyralid requires further investigation, and reminds readers that it is important for composters to follow the manufacturer's label for instructions on how long to compost the material.

Solution in the Works

Yet, even if composters read labels and follow instructions to the letter—which currently stands at a somewhat impractical recommendation of one year's time for composting—this may not be sufficient time to break down the clopyralid.

And, while the U.S. Composting Council believes that part of the problem with clopyralid contamination does stem from inadequate labeling of products containing the herbicide, the label isn't the USCC's primary concern. The organization is worried that the controversy surrounding clopyralid is "erod(ing) the compost industry's hard-won reputation as a source of quality products and a method to economically recycle yard trimmings, agricultural residues, and other feedstocks, while rendering them safe from herbicide residues."

Its recommendations: To correct label flaws, suspend all efforts to develop and register new clopyralid and picloram products, and discontinue use of the product in areas where residues are affecting the quality and use of compost.

S&S Seeds, which distributes materials that may be affected by clopyralid, also recommends that the USCC create a system of lot identification, which would allow them to more closely monitor any composting flaws.

The USCC is currently working with Dow AgroSciences and the Environmental Protection Agency in future evaluations of chemical products within organic recycling systems. The Leaf-let will provide a follow-up article as new information develops.

Albright Seed is a Division of S&S Seeds.

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