Conventional wood preservatives are not only toxic to target bio-deterioration organisms but also to humans, other organisms and the environment. In an effort to find preservatives that are less toxic or non-toxic to man, other organisms and the environment, efficacy of branch bark and heartwood water extracts (0.65 g/ml) of Erythropleum suaveolens (potrodom) and Distemonanthus benthamianus (bonsamdua) were tested on five less used species (LUS) namely, Sterculia oblonga (ohaa), Antiaris toxicaria (kyenkyen), Canarium bediwonua), Celtis zenkeri (esa-kokoo) and Cola gigantea (watapuo) of varying perviousness and retentiveness from varying contents of hydrophobic and water-repellent extractives and/or extraneous substances in wood and/or vessels. Bonsandua extracts were more resistant to leaching, but potrodom extractives improved the durability of Canarium schweinfurthii more than bonsamdua extractives. Potrodom bark extracts could be readily employed to preserve non-recalcitrant low durability timber species such as C. schweinfurthii, and possibly recalcitrant low durability ones such as S. oblonga after some form of pre-treatment and/or under pressure conditions. Improved durability of immersed and brushed LUS was ranked as follows: C. gigantea > C. zenkeri > S. oblonga > A. toxicaria > C. schweinfurthii proving that the natural durability of timber is somewhat dependent on their level of recalcitrance from intrinsic hydrophobic and/or water-repellent extractives and/or extraneous substances. Though extracts showed reduced efficacy with time, the use of potrodom extractives for the preservation (control of pests) of non-recalcitrant low durability wood is promising.

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