Spruce Weevil and Western Spruce Budworm Forest Health Stand Establishment Decision Aids

Abstract

Western spruce budworm (Choristoneura occidentalis) is a defoliator of Douglas-fir throughout the tree's range in British Columbia. Although recent defoliation levels within the Coast Forest Region (CFR) have been primarily light, this insect has caused significant damage within the region in previous years. In the past, western spruce budworm has had its largest impacts in the Squamish and Chilliwack forest districts, particularly in the Pemberton/Birkenhead area and the Fraser Canyon area near Boston Bar.

The spruce weevil (Pissodes strobi) is a major pest in the cfr where it seriously limits the use of Sitka spruce for reforestation. Repeated weevil attacks to the leading shoots of young Sitka spruce trees result in suppressed height growth and stem deformities; however, improving supplies of weevil-resistant planting stock may lead to new reforestation strategies for Sitka spruce.

The Stand Establishment Decision Aid (SEDA) format has been used to extend information on a variety of vegetation and forest health concerns in British Columbia. The two-page SEDAs presented in this extension note were developed to summarize information about spruce weevil and western spruce budworm occurrence and management in the CFR. The first page of each SEDA provides general information, hazard ratings for the CFR's biogeoclimatic zones and subzones, and silvicultural considerations. The second page outlines the growth and yield implications and other effects and associations of these insects. A valuable resource and reference list that readers can use to find more detailed information is also included. Most reference material that is not available on-line can be ordered through libraries or the Queen's Printer at: www.qp.gov.bc.ca.