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Composters Concerned About New Dupont/Scotts Product That Mimics Banned Herbicides

Composting. It’s a traditional part of many home-grown farms and a concept catching on for backyard gardeners as well. But for those who purchase compost, or who choose to compost their own lawn clippings, beware.

Clopyralid, bifenthrin, aminopyralid are all agricultural chemicals that have made news for their inability to break down readily in compost. According to Dan Sullivan, in an article written for Biocycle, this persistence has linked them to major crop damage in some cases, and to shutting off commercial composters from some of their most lucrative markets, in others.

Now it appears there’s a new troublemaker on the block. Dupont has been marketing a new post-emergent broadleaf herbicide to landscapers, lawn maintenance professionals and turfgrass managers — under the name Imprelis.

This is a concern to those in the composting community, who do not like what they read on the label:

“Do not use grass clippings from treated areas for mulching or compost, or allow for collection to compost facilities. Grass clippings must either be left on the treated area, or, if allowed by local yard waste regulations, disposed of in the trash. Applicators must give verbal or written notice to property owners/property managers/residents not to use grass clippings from treated turf for mulch or compost.”

Like its predecessors, many of which were banned because of their persistent qualities, aminocyclopyrachlor- the active ingredient in Imprelis- has been found to remain in grass clippings for extended periods of time. When those grass clippings are composted and used for mulch in gardens, the persistent herbicide- even in trace amounts- can cause major damage to vegetable crops.

Dupont is also teaming up with The Scotts MiracleGro Company to offer a new fertilizer/herbicide product to homeowners that will contain aminocyclopyrachlor. Unlike Imprelis, it will not require a professional pesticide applicators license. It will, however, carry similar label restrictions against composting.

While DuPont continues to assert that label restrictions should take care of any potential contamination problems, the compost industry remains unconvinced. Sullivan’s article quotes Fred Michel, Jr., an associate professor of Biosystems Engineering at The Ohio State University. “They seem to think it’s going to be below the radar and diluted out to the point where there won’t be any effect.” Michel has been working on compost tests funded by Scotts/Dupont, but was unaware the product was already on the market. “The no effect level for beans, however, is very low and below the 2.5-percent level we tested. Beans are very sensitive to these compounds. Let’s say as a worst-case scenario one guy on the block is using it and the other nine aren’t and all the grass clippings go to a composting facility. It gets diluted and it does break down, but only by 40 to 60 percent. So problems may still arise.”

As reported in an article written by Caroline Davies for The Observer in 2008, gardeners across Britain were angered when compost tainted with aminopyralid caused a loss of their crops. It was believed that reconstituted grass containing the herbicide was fed to cows. The manure used from these cows was then sold to farmers and gardeners. Dow AgroSciences, maker of the herbicide, responded on their website with this statement: ‘As a general rule, we suggest damaged produce (however this is caused) should not be consumed.’ Those who have already used contaminated manure are advised not to replant on the affected soil for at least a year.

Compost persistence may not be the only problem, either. In its online June newsletter, the Ohio State University extension reported damage to many of its spruce and pine trees, and questioned whether Imprelis might be to blame. On its website, the Penn State Cooperative Extension is reporting yellowing, distortion, and dieback of spruce and white pine, and are warning landscape managers and arborists that the cause could be Imprelis.

Read full Biocycle article here:

Read full Observer article here:

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