Impact of different sterilization techniques and mass loss measurements on the durability of wood against wood-destroying fungi

Abstract

The biological durability of wood is frequently determined in laboratory tests with monocultures of different decay fungi under ideal conditions for fungal growth. To avoid contamination with mould and inhibition of fungal growth, wood specimens need to be sterilized using different methods. To determine the mass loss of wood blocks during incubation, the initial total dry mass is needed but should be determined without oven-drying to avoid the loss of volatile compounds of the tested wood. In this study the effect of different sterilization techniques in combination with different methods of determining the oven-dry weight on mass loss (MLF) in agar plate wood block tests was investigated. No significant MLF differences were observed between sterilization through gamma radiation, steam, autoclaving, ethanol dipping and oven-drying. Solely, non-sterilized specimens showed reduced MLF, since the test fungus was inhibited by mould growth. Oven-drying of wood species that contain volatile and resistance-affecting compounds such as Scots pine (Pinus sylvestris) led to reduced biological durability and should either be avoided or adapted to kiln-drying temperatures usually applied in practice.