Temperature development and sterilization of red pine poles during CCA treatment, elevated temperature fixation and drying

Micro-organisms present in large red pine poles after air seasoning for 10 months in Quebec Canada were progressively reduced in numbers during CCA tr eatment and fixation and drying under the conditions of the study. Before t reatment, there was a large number of microfungi isolations from both the s apwood and heartwood of all poles and wood decay fungi were isolated from 8 of 20 test poles, primarily from the sapwood zone. After CCA treatment, th e number of microfungi isolated from the sapwood was reduced by about 50%. Basidiomycetes were isolated from 9 of 30 poles after treatment primarily f rom the untreated heartwood and occasionally from unpenetrated sapwood (wet pockets). Moderate temperature fixation schedules (20 hours) achieved temp eratures of 55-60 degrees C for about 5 hours at full sapwood depth and 55 degrees C at the centres of the poles only by the end of the schedule. Howe ver, this temperature regime was sufficient to eliminate most of the micro- fungi, including Trichoderma and all but one isolation of basidiomycetes fr om the heartwood of one pole. During kiln drying, the wood core temperature reached 55-60 degrees C for 9-10 days. After this exposure there were no b asidiomycete isolations. Thermo-tolerant Paecilomyces variotii and several species of Penicillium moulds were evident in a number of poles. Considering the almost complete effectiveness of the fixation exposure to e liminate decay fungi and the higher wood temperatures reached for much long er times during kiln drying, the probability of decay fungi surviving the s equence of processes described in this study is negligible.