Western Spruce Budworm Damage to Sprayed and Unsprayed Young Douglas-Fir
Abstract:Defoliation, mortality, and top-kill were measured in 40-year-old, open-grown Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) under attack by the western spruce budworm (Choristoneura occidentalis [Freeman]) in the interior of British Columbia, in control trees and trees treated with ground sprays of the insecticide Sevin. In untreated trees that sustained repeated defoliation of 50 to 90% of the total crown foliage, tree mortality began after four years and had reached 29% after eight years. Thirty-four percent of the survivors in this group suffered top-kill, which averaged 1.0 m at the end of eight years. No mortality and only negligible top-kill occurred in trees, sprayed or not, which sustained less than 50% defoliation. A regression model of the probability of tree mortality based on the defoliation is presented. West. J. Appl. For. 3(2):44-46, April 1988.
Document Type: Journal Article
Affiliations: Canadian Forestry Service, Pacific Forestry Centre, 506 West Burnside Road, Victoria, B.C., Canada V8Z 1M5
Publication date: April 1, 1988
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- Each regional journal of applied forestry focuses on research, practice, and techniques targeted to foresters and allied professionals in specific regions of the United States and Canada. The Western Journal of Applied Forestry covers the western United States, including Alaska, and western Canada; WJAF will also consider manuscripts reporting research in northern Mexico that has potential application in the southwestern United States.
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