EPA Bans Sale of Suspected Tree-Killing Weed Killer

Clover is not a weed. It's a fertilizer factory for lawns.

Photo: Paul Lampard / Istock

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Original story published July 13. Updated Aug. 12.

Update: On Aug. 4, DuPont stopped selling and recalled Imprelis. On Aug. 11, the Environmental Protection Agency banned the sale or use of Imprelis, at least temporarily. According to the EPA:

This action follows EPA’s investigation into why a large number of evergreens and other trees have been harmed following the use of the herbicide. In its evaluation, EPA is investigating whether these incidents are the result of product misuse, inadequate warnings and use directions on the product’s label, persistence in soil and plant material, uptake of the product through the root systems and absorbed into the plant tissue, environmental factors, potential runoff issues or other possible causes.

Dupont's new herbicide, Imprelis, is considered prime suspect in the death of green living things. That shouldn't be a surprise, given that it's designed and marketed to kill lawn weeds like clover and dandelions. But nearby trees — white pine and Norway spruce (both sold as Christmas trees) — are also dying in enough cases that the company and environmental officials have launched investigations.

Dupont mailed a letter dated June 17 to customers stating that "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 are working to determine what variables may have contributed to the symptoms being observed."

Dupont notes that its chemical might have been applied improperly in cases that trees were damaged, it often wasn't the only chemical used, these species may have been stressed for reasons unrelated to any chemical, and that it has many reports of safe usage without damaging nearby trees. Nonetheless, Dupont recommends that golf courses and others using Imprelis take care not to use it near Norway spruce or white pine.

"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."

The story was first reported by the Detroit Free Press, which suggests the damage from the tree damage could reach into the millions of dollars. Trees are dying throughout the Midwest, East and South in numbers on par with losses from the emerald ash borer, a voracious invasive beetle. Landscaping companies are worried about liability claims, and both federal and state environmental officials are investigating, the paper reports.

Clover, incidentally, need not be considered a weed. Dandelions can be considered salad. They, among other plants known collectively as "broad-leaf weeds" can, however, be kept at bay using organic lawn care techniques that avoid the use of chemical pesticides and fertilizers that often have undesireable or unintended effects on the local environment (or your family's and pet's health). Our Green Cheapskate also recently shared 10 homemade weed killers that are nontoxic (and, of course, cheap).

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