Characterisation of a soft rot-like decay pattern caused by Coniophora puteana (Schum.) Karst. in Sapelli wood (Entandrophragma cylindricum Sprague)

The decay patterns of brown and soft rot fungi in Sapelli wood (Entandrophragma cylindricum Sprague), with respect to natural durability, were examined by light and transmission electron microscopy as well as UV spectroscopy. Analyses revealed that the typical brown rot fungus Coniophora puteana can cause a soft rot-like decay in the sapwood of Sapelli at high moisture contents of approx. 100 %. In accordance with the decay pattern of the typical soft rot fungus Chaetomium globosum, the hyphae of C. puteana penetrated the S-2 wall of fibres and formed characteristic rhomboidal cavities orientated parallel to the microfibrillar angle. However, these cavities were larger in diameter (3.9 mum +/- 0.9) than those formed by C. globosum (2.1 mum +/- 0.5) and with a distinct interspace between the hyphae and surrounding walls. Hyphae of C. globosum were directly attached to the undecayed secondary wall. No lignin degradation for both fungi in close vicinity to the cavities was observed, as evidenced by UV spectroscopy. The inclusion of microscopy for definitive decay type identification is recommended.