Breakdown of Timber by Ascomycetes and Fungi Imperfecti

Soft rot of wood is caused by certain species of Ascomycetes and Fungi Imperfecti The fungal hyphae typically run spirally in the central zone of the secondary xylem walls, where they give rise to cavities with pointed ends. The fungi causing soft rot are cellulose‐attacking species which initiate attack in the less heavily lignified parts of the walls of the wood elements. The rate of attack is increased when inorganic nutrient salts are added to the wood. Under laboratory conditionsChaetomium globosumcan cause severe decay of hardwoods. Soft rot causes serious deterioration of timber in water‐cooling towers and is therefore of considerable economic importance.