The development of decay by soft rot fungus Chaetomium globosum was investigated in young and mature culms of bamboo Phyllostachys virideglaucescens. Soft rot decay was influenced both quantitatively and qualitatively by the differing levels of lignification in the material. Weight loss was significantly greater in the younger culm compared with the older, more heavily lignified culm. The distribution of soft rot decay cavities was also highly variable in the young culm, cavities being much more frequent in the lower lignin fibres of the inner layers of the culm wall. In the mature culm a more homogeneous pattern of lignification resulted in a more evenly distributed decay. Studies with light and electron microscopy showed that soft rot cavity morphology was greatly influenced by the degree of cell wall lignification and stratification. Cavities were usually initiated at the boundary between two layers and, in heavily stratified walls, their form was typically restricted being crescent shaped in transverse section. Variable lignification of the wall layers also had a direct influence, with high lignin levels reducing cavity formation. It is considered that the characteristic pattern of lignification which is influence by age and location in the bamboo culm makes this a particularly useful substrate in which to study aspect of soft rot development.

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