Predicting Douglas-fir Defoliation from the Percentage of Buds Infested by the Western Spruce Budworm

Authors

  • T. L. Shore Canadian Forestry Service Pacific Forestry Centre 506 West Burnside Road Victoria, BC V8Z 1M5
  • R. I. Alfaro Canadian Forestry Service Pacific Forestry Centre 506 West Burnside Road Victoria, BC V8Z 1M5

Abstract

Based on samples from 12 locations collected in British Columbia between 1977 and 1982, a regression model was developed for the relationship between percentage of buds of Douglas- fir, Pseudotsuga menziesii (Mirb.) Franco, infested by western spruce bud worm (WSB), Choristoneura occidentalis (Freeman), and the resulting stand defoliation. This relationship can be used to assess the bud worm population in the early spring , either as a pre-treatment check or to predict damage.

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