Red oak (Quercus rubra L.) is native only to eastern North America. It was first planted in Slovenian forests more than a century ago. The objective of the study was to determine the resistance of red oak wood from Slovenian forests to moisture and fungal attack. Testing of red oak wood was conducted in parallel with testing of European oak (Quercus spp.) and Norway spruce (Picea abies L.) wood. The sapwood is not resistant to fungal decay, and thus only heartwood from selected wood species was used for all tests. We conducted a series of studies on the resistance of wood to fungal decay and wetting. In addition, anatomical and chemical analyses were performed. We made permanent anatomical preparations and compared the influence of the wood structure of European oak and red oak on fungal decay at the microscopic level. The numerous tyloses in the wood of European oak provide a barrier to the progression of fungal hyphae, whereas tyloses in red oak wood are rare and therefore easier to treat. The amount of extractives in the wood, and the percentages of cellulose, lignin and hemicelluloses were determined. Using the Meyer-Veltrup model, we calculated the relative resistance dose of the wood and the time within which the wood is expected to begin to decay based on the wood's inherent resistance to biological deterioration and wettability. Red oak shows nearly the same wetting performance compared to European oak, but is less resistant to fungal attack because it contains lower levels of extractives and tyloses. The study provides good baseline data to facilitate decisions on the use and protection of red oak wood.
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