VIEW ARTICLE

Disease Detection and Losses

Effect of Stand Conditions on Advance of Phellinus weirii in Douglas-fir Plantations. W. J. Bloomberg, Pacific Forestry Centre, Forestry Canada, 506 W. Burnside Rd., Victoria, B.C., Canada V8Z 1M5; Phytopathology 80:553-559. Accepted for publication 18 December 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-553.

Advance of Phellinus weirii in 62 infection centers over five intervals of 5?6 yr from 1958 to 1985 was studied in relation to stand conditions in three Douglas-fir plantations. Stocking level (number of trees per hectare) and average tree diameter were higher in sectors where the fungus advanced than in those where no advance occurred. Advances were more strongly related to tree diameter, whereas failures to advance were more strongly related to stocking level. Species composition or unrelated tree mortality also were associated with failure to advance. The fungus advanced unevenly among octants of centers. Only 1?3% of advances in an octant followed an advance during the previous period, and 76?96% of nonadvances followed nonadvances in the previous period. There were significant differences in advances among plantations, centers, and stand ages. Incidence of P. weirii in plantations was related to both stocking level and degree of tree aggregation.