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Evaluation of mountain pine beetle infestations, Big Belt Mountains, Townsend District, Helena National Forest--1973 Public Deposited
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Mountain pine beetle, Dendroctonus ponderosas Hopk., reached near epidemic levels in lodgepole pine stands in the Sulphur Creek-Black Butte area. Lodgepole pine are probably more susceptible due to the overstocked conditions of stands, and high incidence of girdling of the base of trees by porcupines. The infestation in this area was classified as static with a decreasing trend. Mountain pine beetle and pine engraver beetle, Ips spp., increased to epidemic levels in blowdown and top-broken second-growth ponderosa pine in the North Fork of Roy and Grunett Creek drainages on State, private and Bureau of Land Management lands. Several hundred ponderosa pines are now infested. Sufficient brood is present to cause an increase in number of trees killed in 1974. Several hundred subalpine fir were killed by the fir engraver beetle, Scolytus ventralis Lec., the western balsam bark beetle, Dryocoetes conftisus Sw., and Fityokteines sp. Faded tree groups occur from Duck Creek Pass north to Slough Creek. Most infested groups are adjacent to current or recent logging activity that provided slash and served as a breeding site and source of population buildup.
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