Pine beetle infestation eases; new threats in western Montana

2012-04-05T11:35:00Z 2012-04-06T00:45:32Z Pine beetle infestation eases; new threats in western MontanaBy BRETT FRENCH The Billings Gazette

From the air, the view of Montana’s forests is improving, with indications that the state’s mountain pine beetle infestation is abating.

“Conditions are improving,” said Gregg DeNitto, a Forest Service pathologist and leader of the Forest Service’s Forest Health Protection office in Missoula. “We are seeing a continued decline in mountain pine beetle activity in many areas across the state, indicating the epidemic may have reached

its peak.”

However, new concerns are emerging about western spruce budworm and pine butterfly, particularly in northwestern Montana and the southern Bitterroot Valley.

These are some of the findings from aerial surveys of Montana forest lands conducted last year and compiled in the 2011 Montana Forest Insect and Disease Conditions report prepared by the Forest Service and the state Department of Natural Resources and Conservation.

The report presents county-by-county information gathered from aerial detection flights and ground surveys covering roughly 20.5 million forested acres across Montana, including private, state and federal lands. The survey included locations around Fort Peck, including parts of Garfield, McCone, Musselshell, Petroleum, and Valley counties, areas not previously surveyed from the air. The 2011 survey recorded beetle-caused mortality on more than 1 million acres, compared with 2 million in 2010 and 3.6 million in 2009.

The 2011 survey also identified almost 1.2 million acres defoliated by the western spruce budworm, compared with about 326,000 acres affected in 2010 and 2.6 million acres in 2009. Lincoln, Flathead, and Sanders counties in northwestern Montana were the counties with the highest number of acres affected. Western spruce budworm attacks Douglas fir, spruce, and true fir trees. The insect rarely kills trees but defoliation severely stresses the tree.

Douglas-fir tussock moth and pine butterfly are increasingly active in the western part of the state.

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