Dealers listed Imprelis for hundreds of dollars a gallon, and it flew off shelves.
Then the evergreens started turning brown.
By June, state agricultural extension services in Pennsylvania, Michigan, and Indiana were naming Imprelis as a suspect in the blighting of Norway spruce and eastern white pines, Northern trees which are not native to much of the country but have been planted by the millions in yards, golf courses, cemeteries and parks, in the path of the turf chemical industry's marketers.
After spraying Imprelis in April and May, "professional turf-grass managers from Iowa to New Jersey experienced damage to certain tree species, primarily Norway spruce and white pine," Pete Landschoot, professor of turf-grass science at Pennsylvania State University, wrote in a June warning posted by the university's extension service.
"In some cases, injury does not progress much further than slight curling and browning of new growth; however, in other cases complete dieback is observed. In severe cases, the entire tree turns brown and begins to lose its needles."
It's as if the trees were being poisoned through the roots, from herbicide spread deep by the soaking spring rains, he added. Landschoot noted DuPont's labels warned users to be careful where they spray, since Imprelis has "high potential for reaching surface water via runoff for several months after application."
DuPont on June 17 sent a warning letter to dealers and sprayers. "Do not employ Imprelis where Norway spruce or white pine are present on, or in close proximity to, the property to be treated," warned Michael McDermott, head of suburban Wilmington-based DuPont Agricultural Products, who had introduced Imprelis at industry gatherings all winter.
