EFFECT OF WET STORAGE ON SUBSEQUENT COLONIZATION AND DECAY BY CONIOPHORA-PUTEANA AT DIFFERENT MOISTURE CONTENTS

The effect of wet-storage of wood on the development of the brown-rot fungus Coniophora puteana in pine (Pinus sylvestris) and spruce (Picea abies) sapwood with different moisture contents was studied. Pine log s were wet-stored for ten weeks, sawn, dried and remoistened to initia l moisture contents of 30, 60 and 100 % or exposed to an RH of 100 % a t 20 degrees C for 4, 8 or 16 weeks. Spruce wood was similarly tested but only at an RH of 100 % for 16 weeks (moisture content around 30 %) . There was high variation in the permeability of the wet-stored mater ial. The water absorption of wood in high permeability zones of wet st ored boards was significantly higher than that of low permeability zon es and non-wet-stored wood. The equilibrium moisture content of wet-st ored and non-wet-stored material kept at an RH of 100 % was at the sam e level. When the initial moisture content of pine sapwood was 60 % or 100 %, the development of decay was slower than in wood exposed to 10 0 % RH (a moisture content around 30 %). At high moisture level (100 % MC) the development of decay (mass loss) was initially delayed in hig h-permeable wet-stored wood in comparison with the decay of low-permea ble wet-stored wood and non-wet-stored wood. However, after a 16 weeks ' exposure, the mass loss of the high-permeable wood was higher. Colon isation and decay of spruce wood by C. puteana, as measured by ergoste rol analyses and mass loss, was slower in wet-stored wood than in non- wet-stored wood and the active biomass in wet-stored wood never reache d the levels in non-wet-stored wood over a la-week incubation period a t 100 % RH. Over a longer exposure period at humid conditions (RH 100 %), no significant differences in the decay rate between high-permeabl e wet-stored or non-wet-stored sapwood of pine co;ld be detected. Ther e was a low correlation between the colour of extracts of decayed mate rial and the mass loss values. A slight strength reduction was found a t 3-5 percent mass loss.