Potential for defoliation by western spruce budworm in Douglas-fir stands in eastern Montana, 1975

Aerially visible defoliation by the western spruce budworm, Choristoneura occidentalis Freeman, increased from 149,250 acres in 1973 to 649,319 acres in 1974 on five eastern Montana National Forests. An egg mass survey during the fall of 1974 predicted that additional defoliation will occur in 1975 on 47 of 48 plots located on these Forests. Areas with the highest potential for increasing populations in 1975 are being considered as sites for pilot control projects of several promising chemical and biological insecticides

Evaluation of mountain pine beetle infestations, Lazier and Meadow Creek drainages, Plains District, Lolo National Forest, Montana, 1975

Mountain pine beetle reached epidemic levels in the Lazier-Meadow Creek drainages on mixed ownership in 1972. A total of 118,486 trees with an estimated volume of 5,666,124 board feet was killed from 1972 through 1974. Presence of overstocked, mature, nearly pure lodgepole stands, coupled with favorable weather conditions, are believed to be responsible for outbreak development. Prompt salvage logging of infested and susceptible trees, and conversion to a mixed species stand, compatible with the designated habitat type and site index, are recommended to alter the course of the outbreak

Ground application of dimethoate (Cygon) for the control of cone and seed destroying insects of Douglas-fir and grand fir

Two concentrations of dimethoate were applied with a hydraulic ground sprayer to cone-bearing Douglas-fir and grand fir trees. Single application (mid-June) and a double application (mid-June and mid-July) were compared. Three of the four treatments applied to Douglas-fir resulted in a significantly higher number of sound seeds produced per cone compared to untreated cones. No seed protection was exhibited in the grand fir treatments

Status of mountain pine beetle infestations, Glacier National Park, 1974

Mountain pine beetle populations reached epidemic levels on approximately 4,600 acres in Glacier National Park in 1972. Infested trees increased from 4.9 in 1972 to 10.9/acre in 1975. Majority of trees killed since 1972 were 12 inches d.b.h. and larger in size. Sufficient large diameter lodgepole pine exists to maintain the infestation at epidemic level for several years

Evaluation of Douglas-fir beetle infestations, North Fork Clearwater River Drainage, Idaho, 1974

Douglas-fir beetle, Dendroctonus pseudotsugae Hopk., has caused extensive tree mortality in the North Fork Clearwater River drainage since 1971. In 1974, survey estimates indicated a continued decline in the infestation. Average group size decreased from a high of 158 trees per group in 1971 to 17 in 1974. Average area occupied by each group declined from a high of 4.1 acres per group in 1972 to 0.65 acre in 1974. Attack densities decreased; however, brood-to-parent ratios increased. Natural enemies are having a limited impact on population densities. Availability of susceptible host material may be the primary limiting factor on increased infestation potential. Continued salvage logging of infested trees and susceptible stands is encouraged

Evaluation of mountain pine beetle infestations, Snell Creek and Warland Peak areas, Fisher River District, Kootenai National Forest, Montana

Mountain pine beetle infestations in the Snell Creek and Warland Peak areas were evaluated in October 1975. Based on current buildup ratios, tree diameter distributions, stand composition and phloem thicknesses, there appears to be limited opportunity for epidemic potential in either area. Management alternatives are discussed. Selective logging is recommended to further decrease epidemic potential and reduce the infestations to endemic status

Mountain pine beetle infestation potential for the Plains Ranger District, Lolo National Forest

This report contains an overview of the present mountain pine beetle infestation in lodgepole pine stands on Federal, State, and private lands on the Plains Ranger District. Particular emphasis is placed on the potential for beetle mortality in the Thompson River drainage where recent ground surveys show more than 21 trees per acre were killed in 1978. Management alternatives which can lessen the severity, or reduce the possibilities, of future infestations are discussed

Evaluation of mountain pine beetle in high use areas and other infested stands on the Hebgen Lake Ranger District, Gallatin National Forest, 1977

Mountain pine beetle populations reached epidemic level on the Hebgen Lake Ranger District in 1970. Infested area increased from 6,680 acres in 1970 to 78,000 acres in 1977. Buildup ratio of trees killed in 1976 to trees killed in 1977 is 1:8. Approximately 1,700,000 trees, containing 175 MMBF of merchantable timber, are currently infested. An accelerated program of logging infested trees and silvicultural treatment to reduce the inventory of large diameter trees is recommended. In high use areas (campgrounds and administrative sites), 3,027 trees are currently infested. Buildup ratio is expected to exceed 1:1 in 1978. In high use areas all green lodgepole pine 7 inches d.b.h. and larger, which are to be retained, should be sprayed with the protective spray Sevimol 4. Infested trees should be removed prior to July 1, 1978. Trees that have been dead for several years may be a hazard and should be removed