Efficacy of Tectona grandis (Teak) and Distemonanthus benthamianus (Bonsamdua) Water Extractives on the Durability of Five Selected Ghanaian Less Used Timber Species

Conventional wood preservatives are not only toxic to target bio-deterioration organisms but also to man, other organisms and the environment. In an effort to find preservatives that are less or non- toxic to man, other organisms and the environment, efficacy of heartwood water extractives (0.65g/ml) of Tectona grandis (teak) and Distemonanthus benthamianus (bonsamdua) was tested on five selected less used timer species (LUS): Sterculiaoblonga (ohaa), Antiaristoxicaria (kyenkyen), Canariumschweinfurthii (bediwonua), Celtiszenkeri (esa-kokoo) and Colagigantea (watapuo) by brushing and immersion and exposed to the ground for 8 months following a modified EN 252. Regardless of extract retention in selected LUS, Bonsamdua extract improved their durability more than that of Teak. Improved durability of selected LUS was ranked as follows: Sterculiaoblonga>Colagigantea>Celtiszenkeri>Antiaristoxicaria>Canariumschweinfurthii. Though extracts showed reduced efficacy with time, indications were that they could be employed to control wood pests.