A new herbicide may cause coniferous trees to die. The Quad-City Times reports that a chemical called Imprelis, created by DuPont, appears to cause damage to a few types of trees including the white pine and the Norway and Colorado blue spruce. Among the cities reporting damage are Iowa City and Cedar rapids:
The first damage reports came in late May/early June from the East Coast. Damage has now been reported in Chicago, Iowa City and Cedar Rapids, Iowa, but there has been none in the Quad-Cities, Iowa State University/Scott County Extension horticulturist Duane Gissel said.
Symptoms include twisting and curling, followed by the browning of needles, shoots and branch tips.
Although university Extension horticulturists say it is too early to determine whether affected trees are dead or will die, several nurserymen quoted in a July 14 New York Times article said they know of trees that are dead.
The aforementioned New York Times article points out that DuPont is trying to pass the blame off on those applying the chemical:
In a June 17 letter to its landscape customers, Michael McDermott, a DuPont products official, seemed to put the onus for the tree deaths on workers applying Imprelis. He wrote that customers with affected trees might not have mixed the herbicide properly or might have combined it with other herbicides. DuPont officials have also suggested that the trees may come back, and have asked landscapers to leave them in the ground.
Mr. McDermott instructed customers in the letter 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.
It’s suggested that those noticing damage on their coniferous trees should check to see if Imprelis was used on their lawn. If it was, the damage should be reported to the Iowa Department of Agriculture and Land Stewardship’s pesticide investigator, Richard Colwell.