So many trees have died -- from the East coast west to Iowa and south to the Atlanta area - 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.

Damage on Norway Spruce caused by Imprelis

Many landscapers and lawn services across the U.S. have switched to Imprelis this year to control weeds because it was touted as safer for the environment than predecessors such as 2, 4-D. it also promised to kill weeds such as ground ivy, henbit, dandelions and clover, which were very resistant in the past to herbicides.

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.

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. Tree damage, though, is so extensive that the EPA recently hosted a teleconference with departments of agriculture from several states to gather information about a possible link between Imprelis and the trees.


New growth affected on white pine

DuPont began investigating the problem last month. In a letter addressed to customers, DuPont Professional Products, said Imprelis, which is sold only to professional landscapers, may not have been mixed properly or was applied with other herbicides. A spokeswoman for DuPont, declined to say how many complaints the company had received.

DuPont said Imprelis underwent 400 tests conducted at various universities as to its effectiveness, toxicity and other factors.

"Imprelis has a very favorable environmental profile," the company said, "which is why we do remain excited about the product."

In a community near Ann Arbor, Michigan at least 100 trees look diseased or dead. Many of those homeowners had contracted with the same lawn service.

Symptoms caused by herbicide damage include twisting and curling of the shoot and tips of branches. On the pines and spruces, affected new growth may turn brown and die. On broadleaf plants, upward or downward, bending or twisting may occur on new growth and in extreme cases, new leaves may appear irregular in size and shape (usually smaller than normal) and have abnormal leaf margins. These symptoms are similar regardless if it is an ornamental broadleaf plant or a weed. The new growth on the conifers submitted to labs appeared to be brown and dying. Samples of Norway spruce and White pine submitted to the labs for testing and injury reported in other areas of the country appear to be linked back to the common use of this herbicide applied to nearby lawns for broadleaf weed control. The damage appears to be from root uptake rather than drift.

DuPont recently released a letter to users of the product. Their recommendation is as follows "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."

This product is not available to homeowners, just to landscape professionals. If you or your neighbors use a lawn service contact them immediately to see if Imprelis has been applied to your lawns; you may want to advise them to stop and keep your eye out for damage to trees or shrubs. If any damage is indicated file a claim with the company immediately.

Photo Credits: Purdue University