For wood mycologists, the work of Savory (1954a,b) marked an important step in the understanding of decay processes by lignolytic fungi. His description of decay by ascomycete and deuteromycete fungi in wood from industrial water cooling towers revealed a particular pattern observed previously by Bailey & Vestal (1937), Tamblyn (1937) and Barghoorn & Linder (1944) in wood from other situations. This type of decay was termed ‘soft rot’ because of the spongy texture of the wood surface. Soft rot, characterized by hyphal penetration of the wood cell walls in a fashion similar to sap-stain fungi, results in the formation of decay cavities in the central zone of wood cell walls, which leads to their ultimate destruction. Soft rot was therefore described as distinct from the brown and white rot forms of wood decay normally attributed to lignolytic basidiomycetes and some of the larger ascomycetes, such as members of the Xylariaceae. Indeed, members of the genera Daldinia, Hypoxylon and Xylaria have usually been considered to be white rot fungi. However, the boundaries between these three types of fungal decay have since become less clear-cut and a report in this issue, of a study into hyphal penetration of the reaction zone in beechwood (Schwarze and Baum, pp. 129–140), identifies different penetration mechanisms.