Fungal resistance of Fagus sylvatica after different wood modification processes

The paper describes the resistance of longitudinally compressed ( pleated), heat-treated and impregnated beech wood (Fagus sylvatica) to white rot fungi (Turkey Tail, Trametes versicolor). White rot fungi degrades all constituents of wood with enzymes. Pleating is a chemical-free thermo-hydro-mechanical process, whose primary purpose is to obtain a better bendable, more flexible material. Due to the increased density and decreased cell lumina diameter resulting from pleating, it was assumed that a more fungalresistant wood would be obtained. For pleating, higher density wood species are suitable, therefore we used beech, which is widespread in Hungary and used worldwide. Part of the compression process may be a fixation period (held the specimen in compressed state for a while). Two different fixation periods were used: 1 minute and 3 hours. In addition to pleating, our aim was to test environmentally friendly wood modification methods that may be resistant to fungi and can replace various harmful preservative treatments. We also used the long-known heat treatment at 180 degrees C in aerob conditions, which improves the resistance of the wood to biotic damages due to the chemical changes that take place during the treatment. We also tested samples impregnated with lactic acid by a vacuum treatment, with a positive effect on thermal and dimensional stability. Fungal decay was determined according to the standard EN 113 based on mass losses, and scanning electron microscopy was used to examine fungal mycelium penetration to wood. The longer fixation time after compression has a negative effect on the fungal resistance. Pleated beech samples impregnated with lactic acid proved to be the most resistant. Heat-treated samples as well as non-compressed samples impregnated with lactic acid showed greater fungal resistance to Turkey Tail than the untreated ones.