Effects of New Zealand sapstaining fungi on structural integrity of unseasoned radiata pine

Four sets of green, side-matched specimens of radiata pine (Pinus radiata D. Don) sapwood were incubated with individual isolates of Ophiostoma floccosum, O. pluriannulatum, O. ips, O. piceae, Leptographium procerum and Sphaeropsis sapinea for 8 or 16 weeks, along with non-inoculated control samples. Three decay fungi, Gloeophyllum trabeum, Phlebiopsis gigantea and Schizophyllum commune, were included in the tests to serve as references for weight and toughness loss. Overall toughness and dry weight were not significantly (p<0.05) different between wood specimens inoculated with sapstaining fungi and the controls, except for O. ips #308 causing 18% toughness loss, but not weight loss, in one out of three experiments. In contrast, G. trabeum reduced toughness by 61% and caused a weight loss of 8% whereas S. commune and P. gigantea produced toughness losses of 32% and 16%, respectively, without any significant weight losses. None of the sapstaining fungi tested degraded lignin or structural carbohydrates in radiata pine sapwood after 16 weeks' incubation. Of the isolates tested for their ability to degrade extractives O. floccosum was most effective (54% reduction) and O. pluriannulatum least (0% reduction) effective.