CARBONDALE — As the beetle infestation that has swept across Colorado and much of the West descends on the Roaring Fork Valley, Carbondale town trustees are opting to forego pesticides and instead try synthetic pheromones to discourage the insects from settling on town pines.
They made the final decision Tuesday night to let the town staff give them a try.
Trustee John Hoffmann said he became concerned after researching the pesticides, which he feared would wipe out any natural predators that would attack the beetles and could pollute water supplies.
“They’re long-term cocktails of toxins, basically,” said Hoffmann.
Officials are expecting this summer to be a critical time for mountain pine beetles in Carbondale. Within a month, the young insects are expected to leave their bore holes in infected trees and take to the air and infect new trees, spreading what has become a swath of brown, dead trees in forests throughout the Rockies.
Pines in Summit and Eagle counties already show the scars. Roaring Fork Valley trees have been less affected, but Carbondale Public Works Director Larry Ballenger said trees in town will likely begin turning brown this winter. Lodgepole trees in the town have a 70 percent to 90 percent infestation rate by mountain pine beetles, the family that includes bark beetles, he said.
The threatened spread has left town officials worried about 13 pines throughout town in public rights of way that haven’t been infested but are in danger. The town’s tree board sought to spray pesticides on the trees. Town trustees initially backed the idea, then had second thoughts after Hoffmann raised concerns.
“The decision ultimately was made, we won’t spray this year,” said Town Manager Tom Baker. “We’re asking the tree board to work together to get a comprehensive plan that we can agree on how we can prevent the infestation and where to go from there.”
In the meantime, town staffers looked for an alternative to pesticides, and found one: using a mix of synthetic scent chemicals to keep away the beetles.
Called Verbenone, it is a mixture of manmade chemicals similar to natural ones emitted both by beetles and by pine trees themselves. A packet of the pheromones is stapled to the tree with the hope that it will act as a neon light flashing “no vacancy.” The pheromones are supposed to send the message that the tree has already been infested, so wayfaring beetles should look for another tree somewhere else.
“They have seen some very positive results,” Ballenger said.
Verbenone has been used throughout the country, including widespread use by the Forest Service, he said. Impacts on the environment haven’t been deeply studied, Ballenger said, but no negative effects have yet turned up.
“It’s just benign,” he said. “I don’t know how else to say it.”
Trustee Frosty Merriott said he had reservations, though, that the pheromones may not be benign either.
“We decided we’re going to be chemical free,” he said.
The decision only affects these 13 town trees, though. Town officials have no say over whether or not landowners spray chemicals on their pines to prevent the spread of the beetles.
“What they do at River Valley Ranch or anywhere else in town is what they do,” Baker said. “We just want to make sure the chemicals are used in a professional manner.”
dfrey@aspendailynews.com
