Stem Diseases of Lodgepole Pine in the British Columbia Interior Following Juvenile Spacing

Abstract

The incidence of western gall rust, stalactiform and comandra blister rust, and atropellis canker was measured in four sets of permanent sample plots in young lodgepole pine stands in the interior of British Columbia in 1980 shortly following operational juvenile spacing and again in 1985. The incidence of these diseases in 1980 was often higher in the spaced areas than in unspaced controls indicating that comandra rust infections occurred with equal frequency in spaced and control areas while the increase in the incidence of stalactiform rust was much greater in thinned than in unthinned control areas. The pattern for atropellis canker was not clear. The proportion of trees with one or more infections by these diseases in 1980, and the number of infections per diseased tree, increased significantly with diameter in both thinned and control areas. By 1985 only 60.8 percent of the original number of trees in the thinned areas and 74.8 percent in unthinned control areas remained free of stem infections or threatening branch infections by these diseases.