Effect of preservative treatment on survival of fungi in western red cedarutility poles

The ability of fungi to survive in western red cedar utility poles through the thermal treatment process was explored by removing increment cores from 200 poles before and after treatment. The treatment processes were varied to produce maximum temperatures ranging from 17 degrees to 80 degreesC at t he pith center of the largest pole in a given charge. Although approximatel y 20 percent of the poles contained some evidence of visible decay prior to treatment, only one decay fungus was isolated from these poles. It is gene rally difficult to culture decay fungi from western red cedar heartwood and our results confirm this problem. As an alternative, we used the incidence of non-decay fungi before and after treatment as an indicator of heat effi cacy. The incidence of non-decay fungi declined by 93 to 100 percent, depen ding on the treatment conditions, suggesting that the treatment processes w ere capable of eliminating most fungi from the poles. The paradox between n on-sterilizing temperatures and low fungal survival was believed to reflect the fact that most of the fungi were present in the sapwood, where they we re affected more directly by heat and preservative treatment.