DECAY OF TIMBER IN A WATER COOLING-TOWER BY THE BASIDIOMYCETE PHYSISPORINUS-VITREUS

The water-saturated, chemically untreated inner portions of copper-chr ome-fluoride treated wood fill in a cooling tower, in which water trea tment had been changed from chlorine to ozone, was degraded in a short time by a basidiomycete into a fibrous white rot. The fungus was iden tified as Physisporinus vitreus (Pers.: Fr.) P. Karsten by acanthophys es and plectenchyma formation on agar, fine strands down into the subs trate and crustose mycelial patches. Two isolates were characterized r egarding their biology (temperature, phenoloxidase) and degradation ca pacity of wet specimens (up to 320% moisture content) and of preservat ive-treated (CCF-salt) wood. In piled wood, the fungus attacked microa erophilically only those wet parts which were not surrounded by air. P ine specimens showed an unusual decay pattern as small erosions into t he earlywood, partly black stained due to manganese deposits. The eros ions seem to be related to the mycelial patches developed on agar. Abs ence of chlorine as biocide, supply of some oxygen from the natural de composition of ozone and the low oxygen demand of the fungus may have contributed to the fast and severe timber destruction.