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Imprelis: Strike Two Against New Chemical Weed Killer

Toxicity to Trees is Yet Another Side Effect

We’ve noticed a few emails and even more searches of our database about a new toxic chemical weed killer known as Imprelis. Across the United States folks have been equating applications of the new chemical, manufactured by Dupont, with death or unsightly appearance of their pine and spruce trees.


Although Dupont originally denounced any claims that its product was unsafe to plants other than lawn weeds when used as directed, it now says it’s looking into the matter, according to a letter sent by the company to lawn care professionals (see below). The issue is detailed well in this story in the Detroit Free Press:

The fact that Imprelis — which Dupont touts as far safer than 2,4-D, the lawn weed chemical of choice since 1947 — harms these trees is the second major strike against the product that gained a hasty passage from the EPA for professionals only last year. Last month SafeLawns and other organizations reported that Imprelis doesn’t break down in compost, which means it doesn’t break down in the environment:

The introduction of Imprelis, unfortunately, is repeating a well documented industry practice of trotting out one new chemical after the toxicity of the previous one has been proven. In 2004, for example, when diazinon was finally pulled off the market as an insect killer due to its mammalian toxicity, it was widely replaced with imidacloprid, which causes colony collapse disorder in bees.

Like imidacloprid, Imprelis apparently has lower direct toxicity to humans and is not suspected as a direct carcinogen. That always causes the EPA to streamline the regulatory process — since cancer is virtually the only side effect that the agency really seems to look at with any level of concern.

At the end of the day, ask your lawn care professional to see what they’re using. If it’s a synthetic chemical, tell them not to. It’s that simple.

And you need to be a good student of the language. The greenwashing in the lawn industry right now is deplorable. Right here in New England we have a company known as Simply Safer lawn care that touts an “organic-based” program. Yet that same company announced in its blog this spring that Imprelis was its chemical of choice for weed control:

Maybe the owner(s) of the company meant well, maybe not. But, either way, companies like this are misleading.

When it comes to lawn chemicals, just say no.

In the meantime, here is the letter from Dupont to a Rhode Island lawn care professional, which was obtained by SafeLawns. It appears to be a form letter:

Dear Turf Management Professional,
We are aware that some of your customers are observing various unfavorable symptoms on certain species of trees.

Our turf development team has been investigating these reports and we are trying to better understand the circumstances and whether the various symptoms are related to applications of DuPont™ Imprelis™ herbicide. Our investigation is not complete and we will need your help in gathering necessary information and in determining what variables may have contributed to the symptoms being observed.

While this work continues we want to make you aware of the information we have received to date:

A majority of the reports involve Norway Spruce or White Pine.

In most cases, Imprelis™ was not applied alone, but in a mixture with other herbicides, either pre-emergent, post-emergent and/or with a liquid fertilizer.

Some reports indicate there may have been errors in use rates, mixing practices and/or applications to exposed roots, or the tree.

Most lawn care professionals and golf course superintendents have used Imprelis™ to successfully control weeds and have not reported unfavorable tree symptoms.

As a precaution, until we can more fully understand the circumstances, and whether Imprelis™ may have contributed to the observed symptoms, do not apply Imprelis™ where Norway Spruce or White Pine are present on, or in close proximity to, the property to be treated.

Additionally, when applying Imprelis™, be careful that no spray treatment, drift or runoff occurs that could make contact with trees, shrubs and other desirable plants, and stay well away from exposed roots and the root zone of trees and shrubs. Consult a certified arborist if you are uncertain about the root zone of specific tree species.

In many geographies, environmental conditions over the past few years have stressed trees, particularly spruces. We have observed unfavorable symptoms in trees on properties that have not been treated with a herbicide. Good growing conditions and appropriate care to minimize stress will enable many trees experiencing signs of stress to recover and return to good health.

A DuPont representative will be contacting you within the next 7-10 business days to schedule an appointment to review your observations and gather detailed information relative to this situation. Please help us to make our meeting productive by having application information and other pertinent details ready to discuss.
We appreciate your patience and cooperation as we continue our work.

Michael McDermott
Global Business Leader
DuPont Professional Products

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

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