Impact of pests on the white pine resource of Ontario.
The results are presented of surveys conducted in 1980 and 1983 by the Forest Insect & Disease Survey of the Canadian Forestry Service on the effects of pests and diseases on white pine (Pinus strobus) in Ontario. The most important pest was Pissodes strobi, but Eucosma gloriola, Aphrophora parallela, Pineus strobi and Acantholyda erythrocephala also caused some damage. Growth loss caused by Pissodes strobi was about 8000 m3, annual volume loss was about 15 400 m3, and an additional 15 600 m3 of timber suffered a 25% loss in value due to weevil damage. White pine blister rust (Cronartium ribicola) caused an estimated loss of 8000 m3, and stem decay (caused primarily by Phellinus pini) caused annual losses of about 221 000 m3 in gross merchantable volume. Although decay in natural stands under 100 years of age was negligible, sites of injuries caused by weevils are favourable for infection by decay fungi.