Mountain pine beetles invade area trees

By JESSICA MAYRER Chronicle Staff writer

Mountain pine beetles are attacking Bozeman trees and area arborists say property owners should be on the lookout for signs of often deadly bug infestation, including sappy or white popcorn-like nodules and sawdust around the base of trees.

SEAN SPERRY/CHRONICLE Jeff Pfeil of Bozeman Tree Service points beetle damaged Scotch Pine trees at a South Bozeman residence, Thursday. “I kind of feel like the county coroner driving around,” said Ben Buchanan, from Arbor Medic Tree Lawn & Lot Service.

He’s getting about six calls a day from folks who have sick trees, he said.

Beetles burrow through the bark and eat a tree’s inner circulatory layer. Once that happens, the tree can no longer transport minerals and water, Buchanan said. If not treated with insecticide, a beetle-infested tree will turn brown and die.

Scotch pines on Bozeman’s south side seem particularly vulnerable, said Jeff Pfeil, owner of Bozeman Tree Service. Others varieties, such as Austrian and Ponderosa pines, at this point, appear to be more resistant.

Pfeil’s mother-in-law, Jirina Cikan, has an infestation on her south Bozeman property. When her husband Frank, an architect, drew up the home’s plans, he worked around 21 Scotch pines, to leave them intact.

“It is heartbreaking. I feel like somebody I like is dying,” Cikan said.

Pfeil sprayed the property last week, but signs of the infestation remain. The thick grey trunks of her pines are covered with white nodules.

Pfeil estimates the mountain pine beetle population in Bozeman has tripled in the past three years.

“There’s definitely been an outbreak,” he said.

Pine beetles thrive in warm and dry conditions. In Bozeman, years of drought have weakened trees, breaking down their resistance. Plus, he said, stress triggers a pheromone that attracts the beetles.

“If a tree is stressed, it’s much more likely to attract pine beetles,” he said.

Warm spring temperatures, too, make conditions ripe for beetles. A hard spring freeze after the larvae hatch could slow next season’s epidemic.

When a tree is attacked by beetles, it responds by secreting sap in an effort to push the bug out. The sap hardens and develops into white, yellow, pink or brown popcorn-shaped nodules.

“That’s the key, is knowing what to look for,” Pfeil said. “If you catch it early, it’s very successful.”

And insecticides are effective. Property owners who choose to fight a beetle problem will likely have to spray once a year, Pfeil said. Bozeman Tree Service charges $75 per tree. Arbor Medic’s rates vary, depending on tree size.

If not treated, trees turn brown and die, as has happened across the Northwest. Last year, mountain pine beetles reportedly killed nearly 4 million acres of trees throughout the region, the worst infestation since 1981, when an outbreak killed trees on 4.7 million acres.

“It’s been so dry for so many years and it’s stressing the trees, so the beetles are thriving,” said Richard Miller, insect diagnostician at Montana State University. “If it continues to be dry the population will continue to grow.”

And while insecticide may fend them off, if the weather conditions don’t change, chances are the beetles will sick around, he said.

“You can spray individual trees,” Miller said. “But you can’t spray them all.”

And there’s a downside to spraying, too, Pfeil said. Shipping and manufacturing pesticide is rough on the environment and it kills other, beneficial, insects.

“That’s a definite drawback,” Pfeil said. “You’re chewing up some of the environment in the process of saving a tree.”

Ultimately, folks have to weigh the benefits against the drawbacks, he said. “For a homeowner, the best thing to do is keep a tree healthy and happy.”

Jessica Mayrer can be reached at jmayrer@dailychroncile.com or 582-2635.

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