New herbicide might be killing trees across United States

Jul 15, 2011

The following article was published in the Denver Post on July 15, 2011:

New herbicide might be killing trees across U.S.

By Jim Robbins

A recently approved herbicide called Imprelis, widely used by landscapers because it was thought to be environmentally friendly, has emerged as the leading suspect in the deaths of thousands of Norway spruces, eastern white pines and other trees on lawns and golf courses across the country.

Manufactured by DuPont and conditionally approved for sale last October by the federal Environmental Protection Agency, Imprelis is used for killing broadleaf weeds like dandelion and clover, and is sold to lawn care professionals only. Reports of dying trees started surfacing around Memorial Day, prompting an inquiry by DuPont scientists.

“We are investigating the reports of these unfavorable tree symptoms,” said DuPont spokeswoman Kate Childress.

The company said there were many places where the product had been used without damaging trees. In a June 17 letter to customers, it instructed them not to apply the herbicide near Norway spruce or white pine, or places where the product might drift toward such trees or run off toward their roots.

For some landscapers, the die-off has been catastrophic.

“It’s been devastating,” said Matt Coats, service manager for Underwood Nursery in Adrian, Mich. “We’ve made 1,000 applications and had 350 complaints of dead trees, and it’s climbing. I’ve done nothing for the last three weeks but deal with angry customers.”

So far, the herbicide seems to affect trees with shallow root systems, including willows, poplars and conifers, he said.

Underwood Nursery is replacing the trees, which its liability insurance covers, but faces a $500 deductible for each incident. “It’s already cost us $150,000,” Coats said.

No firm estimate exists on the extent of the tree die-off. But Bert Cregg, an associate professor of horticulture and forestry and an extension specialist with Michigan State University, said the problem existed across the country.

“This is going to be a large-scale problem, affecting hundreds of thousands of trees, if not more,” he said.

Imprelis also is used on athletic fields and cemeteries, he added.

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