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EPA: DuPont Knew Imprelis Herbicide Could Damage Trees

On Thursday, the Environmental Protection Agency ordered a recall of DuPont’s Imprelis, the latest herbicide in the chemical company’s arsenal.

imprelis damage
Suspected Imprelis damage.

Issued under the Federal Insecticide, Fungicide and Rodenticide Act, the EPA order requires DuPont to immediately stop the sale and distribution of Imprelis in the United States and creates criminal penalties for anyone who uses or sells Imprelis.

DuPont’s latest herbicide was approved for use by turf professionals only and was marketed to the landscaping industry as safer and more eco-friendly than its predecessors. In their marketing materials, DuPont stated: “Imprelis™ allows turf professionals to control dandelion, clover and plantains plus the toughest broadleaf weeds — like ground ivy, wild violets and clover — even during reseeding or rainy days. Its single active ingredient has one of the lowest application rates, combined with low toxicity to mammals and low environmental impact. Professionals treating residential and commercial lawns, golf courses, sod farms, and sensitive areas such as schools, parks and athletic fields will benefit from this high level of performance and environmental features.” Low environmental impact, indeed.

EPA’s Imprelis Investigation

EPA launched its Imprelis investigation in July after thousands of landscapers, homeowners, and landowners across the U.S. filed complaints of damage to trees, particularly Norway Spruce, Balsam Fir, and other coniferous evergreens.

The EPA investigation revealed that DuPont actually knew of Imprelis’ potential to damage evergreens, but never included this information on Imprelis’ product label.


The Detroit Free Press reported: “the EPA said that DuPont had test data that showed its herbicide Imprelis was harmful to Norway Spruce, Balsam Fir and other trees when it was given EPA approval last August…Despite that test data, (DuPont) does not warn or caution about potential damage to…certain species of trees.” The EPA does not say if that test data was submitted in the original documents for product approval.

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Did EPA know about DuPont’s test data when it gave approval to Imprelis?

According to a New York Times article on July 14, 2011: “Imprelis went through about 400 trials, including tests on conifers, and performed without problems, according to experts at DuPont and at the E.P.A. The agency reviewed the herbicide for 23 months before granting its conditional approval, meaning that all of the safety data was not yet in but the agency judged Imprelis to be a good product.” New York and California never gave their approval to Imprelis, believing that the product required further testing.

The active ingredient in Imprelis is aminocyclopyrachlor, part of a new class of herbicides viewed as being safer than previous weed killers. In granting conditional approval last August, EPA stated that “aminocyclopyrachlor will not cause any unreasonable adverse effects to human health or to the environment and that the use of the pesticide is in the public’s interest.” (The complete statement was previously available on the regulations.gov website, which is no longer available). Kate Childress, a DuPont spokeswoman, said that studies were submitted to the EPA once it began its investigation. “Among these were studied on the effects of Imprelis on trees, including studies that showed injury to trees under certain circumstances…Everything was done in compliance with (the Federal Insecticide, Fungicide and Rodenticide Act). There was no intent to deceive the EPA whatsoever,” she said.

8 thoughts on “EPA: DuPont Knew Imprelis Herbicide Could Damage Trees”

  1. It is unfortunate that this product recieved such bad press and that it appears to be the cause of tree damage. I have used a similar product which contains another active ingredient in addition to aminocyclopyrachlor and is still on the market but labled for uses other than lawns. This is one of the most effective products I have used. I am involved in herbicide use for a non profit agency and use several different products. When used according to the label, this product is extremely effective over a broad spectrum of broadleaf weeds. Frankly, I consider it to be the greatest discovery since 2,4-D(which has good activity on some weeds but is not nearly as effective or broad spectrum) I am not defending Dupont for its lack of complete knowledge relating to the effect of Imprelis on some trees, but I still feel it’s active ingredient is an exceptional product and certainly does have a place in certain applications. Other than its activity to some desirable trees, it is a very safe product.

    1. Dan:
      Thanks for your input. Unfortunately, when DuPont released an incredibly powerful chemical without proper testing, they put profits ahead of human and environmental health. 2,4-D and aminocyclopyrachlor are indeed effective chemicals and work very well at killing their target weeds. Unfortunately, some weeds are now showing resistance to 2,4-D and that is once again putting crops at risk as superweeds develop. Even more powerful herbicides will now have to be invented.
      We also have to consider the unforeseen consequences which always apply when introducing a chemical into a biological environment. Bacterial and fungi populations decrease in the presence of 2,4-D, and since they’re required to break down the herbicide, that’s a problem. Bacteria is required for soil to function properly and without it, the quality of plant life degrades. Imprelis is simply too new to have any conclusive testing behind it, as it takes years for the tertiary affects of these applications to manifest themselves. That’s why we frequently see these kinds of products banned decades after their introduction.
      We also need to consider runoff. When these chemicals are applied improperly (and they are by homeowners and field hands), rain carries them away through groundwater and into watersheds where they disrupt the endocrine systems of aquatic wildlife. The cumulative effects of synthetic pesticides, herbicides and fertilizers are simply a witches brew. They are tested individually, but need to be tested collectively to study the interactions these chemicals have with one another.

      1. Todd,

        I think you missed the forest for the trees in Dan’s comment.
        Also, do you have any formal training in soil microbiology or weed science?

        I rarely comment on blogs because so many people attempt to say whatever they want regardless of any objective argument backed by facts.
        I have read the Imprelis label several times, and it is clear what precautions need to take place in the landscape. Hopefully the courtroom will bring out those plaintiffs who misused the product and are not being honest about it.

        1. Arnold: Thanks for your comment. Those notorious foot draggers at the EPA issued a stop sale order on Imprelis effectively banning it faster than I’ve ever seen, indicating that there is more to this story than what we’ve so far been told. I spoke with a lawyer representing plaintiffs and although he wouldn’t go on record, he indicated as much.

          Scientists from Purdue University recently stated: In the locations that Purdue and OISC specialists visited, most of the trees that were identified and confirmed as damaged by Imprelis® in 2011 declined in health throughout the 2011 growing season — and they are not recovering in 2012… OISC visited more than two dozen random properties that had trees damaged by Imprelis® in 2011. At each site they sampled leaf tissues and soil samples and collected visual observations… Imprelis® herbicide is still detectable in tree branch tips of both dead trees and plant leaf tissues of damaged trees. It also is detectable in the top 6 inches of soil… . Read their whole account here: https://www.purdue.edu/newsroom/outreach/2011/110722PattonImprelis.html Those are the facts and I could go on for days with many more examples.

          I am not a scientist, just a writer. I assemble a story from the facts available. I’m not against industry making a profit – anybody that invents anything has a right to market it and make billions. What I’m against is DuPont egregiously putting profits before the public interest. After all, these are the guys responsible for the Bhopal disaster in India, where thousands were killed by a toxic gas release from a pesticide factory. Go to this page at the EPA site and you’ll see how many times they’ve been cited for serious violations of various federal policies which put human health in danger: https://cfpub.epa.gov/compliance/cases/index.cfm?templatePage=3&yrNews=&prevYrMon=&srchTyp=0&sortby=TITLE

  2. What has been the response of DuPont Management to the claims of thousands of unsuspecting DuPont customers, professional landscape operators, and victimised home-owners? Ms. Childress, DuPont PR spokeswoman, has sneered these claims in various courts of the land are simply “unfounded”!

    …funfundvierzig..

  3. DuPont’s concealing and evasive Management KNEW beforehand from their secret tests that Imprelis harms trees, according to the EPA. But they took their chances and marketed this fraudulently misrepresented and misbranded weed-killer turned serial tree-killer anyway. With much advertising hype, they claimed dishonestly Imprelis is safe and “friendly to the environment.” Hundreds of thousands of brown, dying and dead trees nationwide immediately following the application of Imprelis attest to the contrary. The total price tag attached to this devastating loss and damage has been estimated to be as high as $1 billion or more. …funfundvierzig..

  4. Walter Cassandra

    Thanks, I have been looking for information about this for ages and yours is the best I’ve located so far.

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