Tree Vigor and Susceptibility to Infection by Phellinus weirii: Results of Field Inoculations : Root and Butt Rots

Uppsala

International Union of Forest Research Organizations, Swedish University of Agricultural Sciences

1994

S. 45-51

17 Lit. Ang.

Bandaufführung

13462

73431

Wounded and unwounded roots of Douglas-fir and mountain hemlock in different vigor classes were inoculated with isolates of Phellinus weirii, the cause of laminated root rot, on 4 study sites in Oregon. Tree vigor differences were determined by computing sapwood basal area to growth ratios. Mycelium grew from inoculum blocks onto roots in 590 of 710 inoculations. After 2-3 years, the total extent of ectotrophic growth ranged from 5.1-72cm with an average extent of 33cm. Ectotrophic growth differed among study sites. Within study sites, no significant difference in ectotrophic growth occurred between trees of different vigor classes. Necrotic flecking of phloem was present beneath surface-colonized bark on 74% of the successfully inoculated roots. Stain columns, ranging up to 52cm in length were observed in the wood of roots that had been wounded. No significant difference in extent of stain occurred between trees of different vigor classes. Phellinus weirii was recovered from stained wood in 49% of attempted isolations. Typical laminated decay was observed on some wounded roots. Vigor-increasing stand treatments, such as tree thinning, do not appear to influence the ability of Phellinus weirii to infect and colonize root tissue.