INOCULATION OF DOUGLAS FIR ROOTS WITH PORIA WEIRII

A method for the inoculation of Douglas fir roots with Poria weirii using Douglas fir, alder, maple, and oak wood for preparing the inoculum is described. When the deciduous wood was used as the food base on which the fungus was grown, a higher percentage of infection was achieved than when either Douglas fir stem or roots were used. Six months was sufficient time for the fungus to become well established on the bark surface; penetration of healthy bark occurred in 12 months. Spread of the fungus to adjacent roots at points of root contact was noted. Growth of mycelium on the bark surface was usually well in advance of infection in the wood. Poria mycelium continued to grow vigorously during the fall and winter months of the study period.