A new herbicide has been linked to the deaths of thousands of trees. The DuPont-manufactured Imprelis was conditionally approved in October by the Environmental Protection Agency for use against clover, dandelion and other common weeds. The chemical, sold only to landscape professionals, has been used on countless lawns across the nation. Imprelis was believed to be an “environmentally friendly” alternative to other herbicides.
According to the New York Times:
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.
But since Memorial Day, DuPont has received numerous complaints that Norway spruces, eastern white pines and other trees were dying in areas where Imprelis was used. “We are investigating the reports of these unfavorable tree symptoms,” Kate Childress, a spokeswoman for DuPont, told the Times. “Until this investigation is complete, itís difficult to say what variables contributed to the symptoms.” The EPA has also begun an investigation.
Matt Coats, an employee of Underwood Nursery in Michigan, explained that the herbicide seems to do the most damage to trees with shallow root systems such as willows, poplars and conifers. His company is replacing the trees lost to Imprelis exposure, which totaled 350 at the time of his interview with the Times. “[That number is] climbing,” he said. “Iíve done nothing for the last three weeks but deal with angry customers.”
“This is going to be a large-scale problem, affecting hundreds of thousands of trees, if not more,” Bert Cregg, a horticulture professor and specialist at Michigan State University, told the Times.
Imprelis, also known as aminocyclopyrachlor, was thought to be among the safest of an emerging class of new herbicidal chemicals. Capable of killing very stubborn weeds such as ivy, DuPont’s researchers found that Imprelis measured very low in toxicity to mammals and could still be effective in small doses. A DuPont official, Michael McDermott, blames the tree deaths on gardeners who mixed the chemical improperly, added additional herbicides to the blend or simply applied too much of it.
Coats described the damage caused by Imprelis, telling the Times that while some trees are simply turning brown, others look “like someone took a flamethrower to them.”
In California and New York, where state environmental laws are more rigorous, Imprelis has not been approved. Researchers in New York believe the herbicide leaches into groundwater; DuPont has yet to provide counter evidence. But experts suggest the odds of an nationwide ban on Imprelis are slim. The EPA is more likely to mandate larger buffer zones for Imprelis or work with DuPont to change the herbicideís labeling, they said.
Photo credit: Kevin Gessner