EFFICACY OF TEAK AND DAHOMA EXTRACTIVE IN TEN LESS USED TIMBER SPECIES

In an effort to find new preservatives which are less hazardous, the efficacy of heartwood water extracts of Tectona grandis (teak) and Piptadeniastrum africanum (dahoma) (0.60 g/ml) were pressure and non-pressure impregnated into ten Ghanaian selected LUS and exposed in the field to the ground for 8 months. Visual durability ratings, hardness and mass losses were measured in assessing their field performance. Though less used timber species (LUS) retained dahoma extract more altogether, teak extract improved the durability of both pressure and non-pressure impregnated LUS more than that of dahoma did.Durability of LUS pressure impregnated with teak extract was finally ranked as follows: P. macrocarpus > A. ferruginea > B. sapida > S. rhinopetala > A. pterocarpoides > C. zenkeri > C. gigantea > S. oblonga > A. toxicaria > C. schweinfurthii. Durability of LUS non-pressure impregnated with teak extract, regardless of impregnation method, was ranked as follows: S. oblonga > C. gigantea > C. zenkeri > C. schweinfurthii > A. Toxicaria.