Aerial surveys of six Montana National Forests in 1975 found a 22.1% increase in the area of visible defoliation caused by the western spruce budworm. It is estimated that 2,278,804 acres of Douglas-fir forests are now suffering at least 25% defoliation. This is an increase of 503,706 acres over the...
Evaluation of four 35 mm film:lens combinations for estimating conifer mortality showed that large-scale true color images obtained with Kodak High Speed Ektachrome and color infrared images obtained with Kodak Ektachrome Infrared, both exposed through a 135 mm lens were best. Higher correlation coefficients were found for the true color:135...
Mortality from various causes was recorded in a Douglas-fir tussock moth, Orgyia pseudotsugata McD., outbreak southeast of Coeur d'Alene, Idaho, in 1974. Observations began June 27 when about 50 percent of the larvae were second instars and continued until pupation. Within a 35-day period, there was a 93 percent average...
Epidemic populations of the western spruce budworm persist in the Northern Region. Aerial surveys made in August 1976 showed a decline in the acreage of aerially visible defoliation. In northern Idaho, the defoliated area dropped from 831,487 acres in 1975 to 655,711 acres in 1976, down 21 percent. Surveys in...
A pilot project to evaluate trichlorfon and acephate for suppressing western spruce budworm populations was conducted on the Helena National Forest, Montana. Both insecticides were applied at 1 pound active ingredient per acre. Application was made with a Bell 205A helicopter using eight Beecomist Model 350 spray heads. Treatments and...
Baseline data for the first year of a two-year study to assess
the current status of ponderosa pine stands in southeastern
Montana relative to coal-fired electric power development are
presented. Sixteen permanent plots in pine stands were established
in eastern Montana, South Dakota, and Wyoming. Several characteristics
believed to be...
A 3-year evaluation of Douglas-fir cones in Montana and Yellowstone National Park, Wyoming, showed the western spruce budworm, Choristoneura occidentalis Freeman, and midges were the most common and injurious insects found each year. Injury was so severe at some plots that no sound seeds could be found.