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Abstract
A sample of 133 Douglas-firs (
Pseudotsuga menziesii var.
glauca (Beissn.) Franco) and 69 true firs (
Abies spp.) with dead tops caused by defoliation by the western spruce budworm (
Choristoneura occidentalis Freeman) were felled, dissected, and examined for height loss and incidence and extent of decay. Height loss was negligible for trees with only the last year or two of their tops killed by defoliation because lateral branches quickly formed new tops. Height losses of trees severely damaged by top-kill averaged 4.3 feet for Douglas-fir and 4.4 feet for true firs, but some trees had new tops with an average length of 0.9 foot for the Douglas-firs and 1.1 feet for the true firs. Only three trees were infected by decay fungi, and associated loss of volume was negligible.
Keywords
Insect damage (-forest,
increment (height),
crown damage,
decay (wood),
heartwood rot,
western spruce budworm,
Douglas-fir,
Pseudotsuga menziesii,
true fir,
Abies spp,
Washington (eastern),
eastern Washington
Citation
Aho, Paul E. 1984. Losses associated with Douglas-fir and true fir tops killed by western spruce budworm in eastern Washington. Res. Pap. PNW-RP-318. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station. 8 p
