Performance of Bark Beetle Damaged Norway Spruce Wood Against Water and Fungal Decay

Norway spruce is one of the most important wood species in Central Europe. Unfortunately, bark beetles have prominently attacked spruce trees. Bark beetles colonize wood in symbiosis with ophiostomatoid fungi, which is visible in prominent blue staining. This reduces the commercial value of the infested wood. The relevant properties of blue stained wood were therefore determined: bending and compression strength, sorption properties, DVS analysis, water uptake, and durability against wood decay fungi. This information was applied in the Meyer-Veltrup model for assessment of material resistance. Scanning electron microscopy analysis confirmed severe infestation of blue stained wood, which was also evident from the color of the specimens. The mechanical properties were almost unaffected, as were the sorption properties. However, the durability and water exclusion efficacy of blue stained wood were considerably decreased, which indicates that decay can be expected to appear faster on blue stained wood than on control-untreated wood specimens.