Imprelis: Another Deadly Herbicide, This Time From DuPont


Spruce TreeThis post was updated Aug. 12, 2011.   

Since 2008, we’ve been reporting on the dangers of pyralid herbicides (including Milestone, Forefront and other trade names), which turn grass clippings, manure or hay into killer compost or mulch that can ruin gardens and farmland for years.

Despite ample evidence that these deadly herbicides are damaging fields and gardens — and despite our calls for the companies and the Environmental Protection Agency (EPA) to solve this problem — we learned another dangerous pyralid herbicide, aminocyclopyrachlor, had been widely sold in the spring of 2011 following its approval by the EPA in August 2010. Invented by scientists at DuPont and sold as “Imprelis,” aminocyclopyrachlor was marketed to control weeds in cool-season lawn grasses, especially bluegrass.

After one season of use, Imprelis has been implicated in the injury or death of thousands of trees. Conifers that are growing in or near grassy areas treated with Imprelis, and are showing new growth that is brown and twisted, have been reported in Pennsylvania, Minnesota, Iowa, Delaware , Indiana, Nebraska , Wisconsin, and several other states. Michigan State has published an advisory on What to Do With Imprelis-Affected Trees, and Purdue University in Indiana has set up channels for Imprelis related herbicide complaints, as have Nebraska and Wisconsin. And what will happen when the chipped wood from these poisoned trees ends up at compost facilities? DuPont never denied Imprelis-treated lawns would create killer compost. Lost in a 19-item bulleted list on Page 7 of the nine-page Imprelis label, we found this language:

“Do not use grass clippings from treated areas for mulching or compost, or allow for collection to composting 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 owner/property managers/residents to not use grass clippings from treated turf for mulch or compost.” 

Come on, people! How likely is it that most users will remember this from a 9-page label, let alone warn others not to use clippings for hay, mulch or compost? Despite our knowledge of the severe problems these herbicides are causing, the EPA continues to allow chemical companies to sell them and hide behind their “the label is the law” excuse by putting unrealistic instructions and a liability release on the product labels.

Barbara Pleasant_3
8/4/2011 8:49:05 AM

As of this week, Jeff Schalau, extension agent in Yavapai County, says there have been no reports of Imprelis damage in Arizona. He notes that it is not recommended for use on bermudagrass, and most Arizona lawns are bermuda. The related herbicide that has polluted the compost stream in Washington and other states, clopyralid, also is rarely used in Arizona because it has been found to kill many species of native cacti. You do need to be concerned about aminopyralid, which is used to control weeds in ditches in Arizona. States seem to have more power than the EPA to say no to these dangerous and persistent pesticides. Contact your state congress people about banning these pesticides in your state.

8/2/2011 4:10:02 PM

Since "warmer" climates are mentioned can I safely say that hay grown in Arizona would be considered safe? Most of it is grown in Fort Mohave, a VERY warm place. Thank You.

7/31/2011 10:37:58 AM

With apologies to Joyce Kilmer, 1886–1918 TREES I think that I shall never see A weed as lovely as a tree A tree whose ugly brown is prest Against the poisoned earth’s flowing breast; A tree that may in summer wear A nest of toxins in her hair, A tree that looks to God all day, And lifts her leafy arms to pray, “Why did you Imprelis spray?” Poems are made by fools like me, But only DuPont can kill a tree. funfundvierzig…funfun..July 31, 2011 @ 8:33 AM EDT

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