Pine-pine gall rust on young jack pine in northwestern Ontario
1990
Juzwik, J. | Chong, N.
Pine-pine gall rust, caused by Endocronartium harknessii, accounted for > 99% of all stem rusts encountered during a 1987 survey of jack pine in 71 plantations regenerated with planted stock or by seeding between 1979 and 1984 in northwestern Ontario. Significant differences in rust incidence were detected among the six districts in the region (p < 0.05) with mean incidence ranging from 6.7 to 17.2%. Trees with main stem galls were found more frequently than trees with only branch galls. The majority of main stem infections in 44 plantations where incidence of main stem galls was > 5% were in the potential impact class where deformity or mortality was imminent (P < 0.05). The average level of mortality attributed to rust was low (3.4%). Implications of the results to the region's jack pine tree improvement program and to stand management are discussed.
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