Assessment of the natural durability of four Ghanaian hardwoods against the white-rot fungus Coriolus versicolor and soft-rot using laboratory tests

IRG/WP 03-10498

C Antwi-Boasiako, A J Pitman, J R Barnett

The natural durability of two lesser-utilized species (LUS) (Corynanthe pachyceras Welw. (pamprana) and Glyphaea brevis (Sprengel) Monachino) (foto) from three forest districts, and two related primary species (Nauclea diderrichii (de Wild.) Merr. (opepe) and Nesogodornia papaverifera (A. Chev.) R. Capuron.) (danta) from one district in Ghana is assessed against Coriolus versicolor Linnaeus Quelet and soft rot. Durability of wood from different radial and axial positions in each stem is assessed using modified EN113 and EN(V)807 tests. Mean percentage weight losses (%MWL) are compared to determine the influence of position in the stem and growth site (for the LUS) on durability. Natural durability classes are also determined. Radial and axial variations in durability exist within the stems of all four hardwoods against C. versicolor and soft rot. At the same axial position, radial durability normally increases progressively from the outer sapwood towards the inner heartwood, whereas at the same radial positions, durability normally decreases from the base to the crown of the stem. Occasionally, the middle and crown are more durable. Growth site also influences durability of the LUS. For the primary species, the natural durability classes determined in this study differ from those assigned to them in literature. Durability ranking for the hardwoods against white rot is: N. diderrichii> C. pachyceras> N. papaverifera> G. brevis; with that against soft rot being: C. pachyceras >N. diderrichii >N. papaverifera >G. brevis.

Keywords: Corynanthe pachyceras, durability, Glyphaea brevis, lesser-utilized species, Nauclea diderrichii, Nesogodornia papaverifera, soft rot, white rot

Conference: 03-05-18/23 Brisbane, Australia

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