Resistance of bioincised wood treated with wood preservatives to blue-stain and wood-decay fungi

Bioincising is a biotechnological process that aims at the improvement of wood preservative uptake in wood species with a low permeability, such as Norway spruce (Picea abies (L.) Karst). The process is based on a short-term pre-treatment with white-rot fungus Physisporinus vitreus. During incubation the membranes of bordered and half bordered pits are supposed to be degraded by fungal activity resulting in a better treatability of the wood structure for wood preservatives. In the present study, first of all the resistance of bioincised Norway spruce heartwood and untreated controls against blue-stain and wood-decay fungi (white- and brown-rot) was determined. Then, bioincised and untreated specimens were dipped or vacuum impregnated with six wood preservatives and substance uptake was assessed gravimetrically. Additionally, the penetration of 3-iodo-2-propynyl butylcarbamate (IPBC) into the wood was analyzed by high-pressure liquid chromatography (HPLC). Finally, wood resistance was assessed according to the European standards EN 152 and EN 113. Results showed no difference between bioincised wood without preservatives and the untreated wood against blue-stain discolouration. However, a significant (P < 0.05) increase in susceptibility against wood decay was recorded. In the bioincised wood samples a significantly higher uptake of all the different preservatives was determined and the HPLC-method revealed that IPBC penetrated deeper into bioincised wood than into control samples. The improved uptake of preservatives into bioincised wood resulted in a significantly higher resistance against white- and brown-rot fungi. However, only a slight protection against wood discolouration by blue-stain fungi was recorded. The results of this study show for the first time that the biotechnological process with P. vitreus can be used to improve wood durability by increasing the uptake and penetration of wood preservatives.