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Experts discuss beetle problem, forest health

It’s no surprise to anyone familiar with the forests of western North America: insects and diseases have had a huge impact on the forests and increased the mortality of a variety of tree species.

To discuss this issue with the people of Pagosa Springs, Sky Stephens, forest entomologist with the Colorado State Forest Service, gave a presentation Tuesday entitled, “Beetles and their Impact on Forest Health.”

About 40 individuals showed up to the presentation prepared with questions on topics from what the future of the forest may hold to how to protect trees on their own property.

One interesting note that Stephens brought up concerned the ponderosa pine stands in Archuleta County.

“The last two days, I have seen the best ponderosa pine that I have seen since leaving northern Arizona (years ago),” Stephens said. The ponderosa pine in most states have been ravished by the mountain pine beetle and western pine beetle. The question Tuesday night, however, was why haven’t the ponderosa pine of San Juan National Forest succumbed to the attack by these beetles?

There was no definitive answer.

Kent Grant, district forester for the Colorado State Forest Service, explained that ponderosa pine has thicker bark and is better protected. Grant suggested that this might contribute to the trees’ resiliency.

Daniel Wand, assistant district forester, had a different theory, which hinged on the soil related to elevation. Ponderosa pine in this region grow at elevations with soil more prone to containing clay and holding water.

Scott Wagner, fuels forester for the USFS Pagosa Ranger District, had another theory: Mountain and western pine beetle tend to move into ponderosa stands from lodgepole pine, a tree quite uncommon in this region.

Whatever the reason, it is not a given that ponderosa pine will last or go the way of Douglas fir and Engelmann spruce. However, Stephens and Wagner gave the crowd a reassuring word: forests are not dying out. While the overstory of mature, large spruce are dying in the area, there are young trees in the understory that, by the death of the older trees, will be given a better chance of survival.

“Forests adapt,” Wagner said, adding, “We’ll have forests to deal with.”

In regard to managing individual landscapes, Stephens told the audience there were options, but only if beetles had not infiltrated a tree’s bark. Once a tree is infested, it will die.

Stephens said the chemical sprays Sevin SL and Bifenthrin, if applied correctly, would protect a tree. Also, pheromones could be used, but also must be applied correctly. Stephens notes that the chemical sprays must be applied directly to the bark.

For more information, Sky Stephens can be contacted by e-mail at

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