DETROIT -- In neighborhoods nationwide, millions of dollars worth of Norway spruce and white pine trees are mysteriously turning brown and dying this summer, and the chief suspect is a new lawn chemical.
State officials and lawn care professionals say they think Imprelis, an herbicide introduced last year for commercial use by DuPont, may be attacking pines and spruces as if they were weeds.
DuPont has sent its own teams across the country to check out complaints and, for the moment, has recommended not spraying Imprelis near those types of trees. The company says the herbicide may not have been handled properly.
Many landscapers switched to Imprelis this year to control weeds such as dandelions because it was touted as safer for the environment than predecessors such as 2, 4-D.
So many trees have died -- from the East Coast west to Iowa -- that the damage is projected to be in the millions of dollars, and now many states and the U.S. Environmental Protection Agency are investigating the possible link to Imprelis.
Amy Frankmann, executive director for the Okemos-based Michigan Nursery & Landscape Association, said she has not seen such widespread tree damage since the emerald ash borer decimated the state's ash trees.
"I'd say this is right up there as far as the significance and losses," Frankmann said.
Mark Underwood says he thought he was doing the right thing, both for his family's lawn care business and the environment, when he switched to Imprelis, a new herbicide.
But a month after crews from his Adrian-based Underwood Nursery sprayed the DuPont weed killer on hundreds of lawns in southeast Michigan, the calls began.
"The customers are calling: 'My trees are dying, what's up?' " Underwood said. "We've never experienced anything like this."
In what some say could be one of the biggest disasters of its kind since the emerald ash borer killed millions of trees, white pine and Norway spruce trees are turning brown or dying all around the country. Tree damage has been reported throughout the Midwest, in East Coast states and as far south as Georgia.
No one can say with certainty what's causing it, but many lawn-care professionals and state officials suspect Imprelis, which the U.S. Environmental Protection Agency approved last year. The chemical is supposed to kill such weeds as dandelions and clover, which absorb it through their roots and shoots.
Tree damage, though, is so extensive that the EPA hosted a teleconference last week with departments of agriculture from several states to gather information about a possible link between Imprelis and the trees.
The Michigan Department of Agriculture and Rural Development is studying sites of damaged trees and gathering samples of wood and soil. Michigan State University Extension is monitoring the situation and also has visited sites following complaints from landscapers.
DuPont, the chemical giant based in Wilmington, Del., began investigating the problem last month. In a June 17 letter addressed to customers, Michael McDermott, global business leader for DuPont Professional Products, said Imprelis, which is sold only to professional landscapers, may not have been mixed properly or was applied with other herbicides.
Until more is known, he urged customers not to apply Imprelis near Norway spruce or white pine.
Calls to the EPA's regional office in Chicago, which coordinated a conference call on the tree damage with officials in several states, were referred to the Washington, D.C., office. An agency spokesman said he would get back to the Detroit Free Press but did not.
Although the problem is only months old, landscapers could be in trouble if their insurance companies don't pay and they are on the hook for replacing trees.
"I'm getting calls almost daily from landscapers or the landscapers' insurers," said Bert Cregg, an associate professor in MSU's Departments of Horticulture and Forestry. They ask, 'Who's liable here?' and those kinds of questions. It's really a big mess."
Kate Childress, spokeswoman for DuPont, declined to say how many complaints the company had received.
"We're taking this seriously," she said. "We're very committed to understanding the circumstances and what caused the unfavorable symptoms" in the trees.
Is Imprelis damaging trees? "I'm not in a position to say yes or no," Childress said.
"We do recommend everyone keep records and document everything," she said.
She said Imprelis underwent 400 tests conducted at various universities as to its effectiveness, toxicity and other factors.
"Imprelis has a very favorable environmental profile," Childress said, "which is why we do remain excited about the product."
David Gardner, an associate professor in the Department of Horticulture and Crop Science at Ohio State University, said he has been testing Imprelis on weeds. Since 2006, he has done 32 field studies including varying formulations of the herbicide.
"Millions of dollars worth of research goes into getting these products registered," Gardner said.
(c) 2011, Detroit Free Press.
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