Natural and enhanced wood durability from pine heartwood phenolics

Wood is a naturally occurring, complex, structured, polymeric material comprised of a structural matrix in which are embedded a vast variety of extractible compounds. The organic carbon-rich matrix is susceptible to biodeterioration by a wide range of bacterial, fungal, insect and other organisms, despite protective effects of the extractives. Wood preservatives developed over the past 50 years have provided efficient ways of preventing biodeterioration, but many of them are under threat from an increasingly chemophobic populace. Naturally bioactive wood extractives offer promise of control of many wood destroying organisms, and may be more acceptable than these more powerful synthetic biocides. Phenolic compounds, relatively abundant extractives from the heartwood of Pinus spp., plantation-grown worldwide, were evaluated for bioactivity. Heartwood from Pinus spp. containing elevated phenolic concentrations was more resistant to subterranean termites than that from species characterized by low phenolics. While the stilbene phenolics were poorly related to resistance, the flavonoid phenolics appeared to be more closely associated with resistance. However, unspecified additional heartwood compounds contributed strongly to termite resistance. Both Pinus el/iottii and Pinus caribaea, previously classed with Pinus radiata as susceptible to termite attack, were naturally resistant to two significant Australian termite species. Acceptance of this resistance has enabled previous limitations on unpenetrated heartwood in these spp. to be removed from Australian requirements for preservative treatment against termites, with consequent economic benefit to the preservative treatment industry and consumers