This study evaluated decay and termite resistance of wood treated with tar oil obtained from a commercial pyrolysis process of macadamia nut shells. Vacuum-treated pine wood specimens were subjected to various brown and white rot fungi based on the soil-block test method specified by the American Wood Protection Association (AWPA) after leaching process. Treated specimens were also subjected to the subterranean termite attack according to Japanese Industrial Standards (JIS) for 3 weeks. In the study, growth inhibition of selected fungi with the tar oil was tested in vitro. Treated wood specimens at 460 kg/m3 retention level showed good protection against all fungi tested. Mass losses in leached specimens were less than those observed in unleached specimens. Similar results were seen when the specimens were subjected to termite attack. Inhibition tests showed that higher concentrations of the tar oil are critical for inhibition of the brown rot fungi compared to the concentrations required to impede the white rot and sap staining fungi tested.

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