196 research outputs found
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Cultural control of mountain pine beetle in second-growth ponderosa pine stands, Lolo National Forest : proceedings of a meeting held March 16, 1973, Forest Service Auditorium, Missoula, Montana
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Forecasting western spruce budworm defoliation in mixed conifer stands by counting hibernating larvae
An attempt was made in January 1971 to relate the numbers of hibernating western spruce budworm larvae on a square foot of bark surface with subsequent shoot damage on Douglas-fir and grand fir in northern Idaho.
Twenty-six plots sampled in January were also sampled in April to determine
if larval mortality due to breaking dormancy in midwinter occurred.
An average of 3.9 and 1.8 larvae per square foot of bark surface occurred
on Douglas-fir and grand fir logs respectively in January. In April, the
average was 7.7 on Douglas-fir and 3.0 on grand fir. In January there
was a significant difference between numbers of larvae on Douglas-fir and
grand fir logs, but no difference in April. There was no significant
difference in numbers of larvae on Douglas-fir logs between January and
April, but there was a significantly higher number of larvae on grand fir
logs in April.
A regression analysis was made to obtain the correlation between larvae
per square foot of bark surface in January and resultant foliage damage
(sampled in September). There was no correlation on grand fir plots,
and only a weak correlation on Douglas-fir plots
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Evaluation of a Douglas-fir tussock moth outbreak in the lower Flathead Valley, Montana
An aerial survey during 1974 revealed approximately 5,000 acres of various degrees of Douglas-fir tussock moth, Orgyia pseudotsugata McD., defoliation in the lower Flathead Valley. An egg mass survey was made in September to determine the potential for damage in 1975. Based on new egg mass densities, significant defoliation may occur on 2,880 acres
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Potential for defoliation by western spruce budworm in northern Idaho and Montana, 1977
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 Montana found a net decrease in defoliation of 11 percent, down from 2,797,986 in 1975 to 2,496,274 in 1976. Egg mass surveys made in September and October 1976 indicate that defoliation will be light on the Clearwater and Nezperce National Forests and moderate on the Idaho Panhandle National Forests, Idaho, in 1977. Defoliation in Montana during 1977 is expected to be light on the Flathead, moderate on the Kootenai, and heavy on the Beaverhead, Bitterroot, Deerlodge, Gallatin, Helena, Lewis and Clark, and Lolo National Forests and the Flathead Indian Reservation
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Survey of hardwood defoliation in the Turtle Mountains, North Dakota
A looper, probably the Bruce spanworm, Operophtera bruceata (Hulst), defoliated more than 15,650 acres of quaking aspen in the Turtle Mountains of North Dakota in the spring of 1973
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Impact of egg viability, egg parasitism, and virus on 1974 Douglas-fir tussock moth defoliation potential in western Montana
Douglas-fir tussock moth egg mass studies during winter 1974 indicate that natural factors such as low egg viability, egg parasitism, and virus do not alter the potential for heavy defoliation in two sections south of Frenchtown and one section northwest of Lolo, Montana
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Observations on the decline of western larch defoliated by larch casebearer in the northern region
Numerous stands of western larch, Larix occidentalis, on the St. Joe, Coeur d'Alene, and Kaniksu National Forests, Idaho, show signs of gradual deterioration following repeated defoliation by larch casebearer, Coleophora Zaricella Hbn. (Tunnock et al. 1969). Stand deterioration can occur after 4 years of continued heavy defoliation. The main symptom is epicormic branching. Upon examination, many of these dead and dying larch have been infested by the western larch borer, Tetropium veZutinum LeConte, or infected by root rotting fungi. The objective of this study was to determine if larch severely weakened by larch casebearer feeding would die if they were not attacked by borers or root rots
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Status of Douglas-fir tussock moth infestations in the northern region, 1973
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Western spruce budworm egg masses for predicting defoliation potential in the northern region : progress report
An attempt was made to predict western spruce budworm defoliation using
egg counts from plots in the Douglas-fir type east of the Continental
Divide in Montana, the Douglas-fir type west of the Continental Divide
in Montana, and the mixed grand fir Douglas-fir type of northern Idaho.
The parameters used in a linear regression model for the three
ecotypes were eggs per 100 buds in 1972 as the independent variable and
percent defoliation in 1973 as the dependent variable. Correlation
coefficients (0 were: 0.39, 0.54, and 0.66 for the data from grand
fir in northern Idaho and Douglas-fir in eastern and western Montana
respectively. A covariance analysis of the three regression lines
showed there were differences between the three ecotypes
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Mountain pine beetle infestations in the northern region during 1985
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