Ipso facto: Bark beetles spell trouble for pinons
Post Independent Staff
Bob Hammon says there’s one word to describe western Colorado’s pinon forests.
“Changing,” he said.
Look around local pinon-juniper forests, and it’s easy to pick out red-needled pinon trees standing dead among healthy green conifers.
Hammon, from Colorado State University’s Tri-River Cooperative Extension, and several experts spoke to 100 ranchers, landowners and residents on Thursday afternoon at the New Castle Community Center. He was one of several presenters at the 13th annual Ag Day, a free seminar which this year focused on conservation easements, West Nile disease and the Ips beetle infestation.
In Colorado, older pinon trees in crowded forests throughout the West Slope are already stressed from the state’s drought conditions. That makes them prime targets for the Ips beetle, a native bark beetle the size of an uncooked grain of rice that attacks and eventually kills pinon trees.
The beetles bore into the tree, and engrave tell-tale pitchfork-shaped trails into the wood, where they lay eggs beneath the bark. The tree fights back by emitting pitch, or sap, in an attempt to “ooze the beetles out,” according to Roy Mask, an entomologist with the U.S. Department of Agriculture in Gunnison. But the beetles almost always prevail.
“If you see piles of bark dust at the base of a tree, it’s a goner,” Mask said. “It’s already been colonized.”
In a single beetle season, which runs from April to October, four generations of beetles can generate countless offspring.
“Their reproduction rates are tremendous,” said Hammon.
Mask said the current Ips beetle outbreak, which in two years has escalated into a full-fledged war, has prompted officials to take direct measures.
“We’re doing aerial surveys,” Mask said, of infrared photographic studies completed in 2003 to assess beetle damage.
He said trapping studies are also being conducted at infected trees, to monitor exactly how the beetles attack and react to trees, and to determine just how quickly the beetles can move across the landscape.
Mask said preventative spraying trials are determining what kind of insecticide is best for controlling the beetles. He said clearing and pruning can be used to combat further infestation and to prevent wildfire at the same time.
“These are short-term measures,” Mask said. “We have to look at short-term solutions to manage the infestation in the long run.”
Because the beetles are dormant during winters, January and February are ideal times to protect trees from being invaded.
Kelly Rogers from Colorado State Forest Service said the beetles are attracted to pheromones emitted when trees are cut down or pruned.
“That’s why now is the time to do your thinning and cutting,” said Rogers. “You don’t want to be attracting beetles while you’re working to protect your trees.”
Rogers also said watering pinon trees during the heat of the summer can also ward off infestation.
However, Hammon warned against saving every single pinon.
“You have to be realistic,” Hammon told the crowd. “You’re not going to save the entire forest, but you can select the trees you really love and want to protect.”
Hammon said insecticide use should be done in the spring. In this region, he said, that means April.
“You need to start early,” he said. “You want to get to the trees before the beetles get to them.”
Hammon said insecticides with more than 20 percent active agent should be used. Any less, like those found in general household garden varieties, won’t be strong enough to do the trick.
He said landowners can expect to pay $1.25 and up per tree per application for insecticides. Most trees will need one or two applications per season, he added.
In the Roaring Fork and Colorado river valleys, the Ips infestation isn’t nearly as severe as it is in southwest Colorado, but the overall outlook is grim.
“There are two endings to this scenario,” said Hammon. “Either we’ll move into normal precipitation levels, or all pinons will be dead.”
Mask said even though it’s distressing to witness trees falling victim to the Ips beetle, it is a natural occurrence.
“In the last 10,000 years, there have been outbreaks,” he said of pinon-juniper forest cycles. “It’s happened before, and it will happen again.”
Contact Carrie Click: 945-8515, ext. 518
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