Open access publications in the SLU publication database

Abstract

The ability of three soft rot fungi to form cavities in birch sapwood (Betula sp.), was investigated, viz. Allescheria terrestris Apinis (strain Apinis and strain H63-1), Margarinomyces luteo-viridis v. Beyma (strain Beyma and strain M74-IV) as ivell as Phialophora richardsiae (Nannf.) Conant (strain BB40-V). The primary aim of the studies was to elucidate how rapidly the fungal hyphae form cavities after infection of the wood. The role of nitrogen in cavity formation was studied by comparing the time taken for cavity formation in untreated wood and in wood impregnated with various nitrogen compounds. Phialophora richardsiae reacted most strongly to the addition of nitrogen compounds to the wood, forming cavities after three days, as compared with six days in untreated wood. Allescheria terrestris and Margarinomyces luteo-viridis formed cavities two days after infection of the wood, regardless of whether nitrogen was employed or not. However, in nitrogen-impregnated wood, cavity formation began at a more uniform rate and to a greater extent than in untreated wood. The "T-shaped branching" form of attack frequently occurred, in various forms, in that the bore-holes were not always symmetrically related to the long edge of the cavity. The ability of Allescheria terrestris and Margarinomyces luteo-viridis to form cavities in 25 different plants with lignified cells was studied. Cavity formation differed widely between softwood where there was little and hardwood where cavities were very numerous aslthough with some small variations.