Canadian Forest Service Publications

Aerial applications of nuclear polyhedrosis virus and Bacillus thuringiensis against western spruce budworm. 1979. Hodgkinson, R.S.; Finnis, M.; Shepherd, R.F.; Cunningham, J.C. Fisheries and Environment Canada, Canadian Forest Service, Pacific Forest Research Centre, Victoria, BC. Joint Report No. 10, co-published by the BC Ministry of Forests. 19 p.

Year: 1979

Issued by: Pacific Forestry Centre

Catalog ID: 1803

Language: English

Availability: Order paper copy (free), PDF (download)

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Abstract

Three 20 ha plots of Douglas-fir trees infested with five instar larvae of Choristoneura occidentalis were aerially treated at a rate of 750 billion polyhedra/ha with a nuclear polyhedrosis virus which had been propagated in C. fumiferana. At 15 days post-spray, NPV infection levels were 25, 55 and 87% and population reductions owing to treatment were 0, 26 and 48%. Moth emergence was lower in treated plots and the male:female ratio was 2:1 in treated plots compared to 1:1 in check plots.

Four 40 ha plots were similarly treated with Bacillus thuringiensis at a rate of 20 BIU/ha. At 15 days post-spray, population reductions owing to treatment were 32, 66, 79 and 91%. The proportion of moths emerging and the number of eggs laid were similar to check plots. No consistent foliage protection was obtained with either treatment.