Natural resistance of plantation grown African mahogany (Khaya ivorensis and Khaya senegalensis) from Brazil to wood-rot fungi and subterranean termites

Abstract

African mahogany (Khaya spp.) has attracted the interest of the timber market in Brazil because of the quality of the wood and the similarity to the highly demanded, Brazilian mahogany (S. macrophylla King). The goal of this study was to examine natural resistance of plantation-grown African mahogany (Khaya spp.) to decay fungi and termite feeding, in order to better evaluate the potential use of this material as a suitable replacement for Brazilian mahogany wood. Heartwood and sapwood of two African mahogany species, Khaya ivorensis and Khaya senegalensis, were evaluated for resistance to decay by five wood-rot fungi as well as to feeding by subterranean termites in laboratory tests. In addition, density values were evaluated and examined for correlation to the observed natural durability properties. Overall, results showed heartwood of both species to be more resistant than sapwood to all fungi tested. K. senegalensis sapwood showed the lowest resistance to decay fungi, while K. senegalensis heartwood had the highest resistance to both brown- and white-rot fungi as well as to the dry-rot fungus tested. Both wood species showed some resistance to feeding by subterranean termites, with significantly higher resistance in heartwood compared to sapwood. In fungal and termite tests, durability was not found to be correlated to density values for either Khaya spp. tested. Results from this study suggest plantation-grown African mahogany exhibits similar natural durability properties as Brazilian mahogany, supporting the potential for its use as a suitable substitute to better meet the demands of the wood products industry.