Evaluation of extractives from African Padauk (Pterocarpus soyauxii Taub.) for protection of non decay resistant species
P Nzokou, D P Kamdem
The development of a wood preservative made up of natural extracts is a potentially attractive prospect for the wood preservation industry. In this study, organic solvents were used to remove extractives from African padauk wood samples. The solvent was removed by rotoevaporation, and the total content of the viscous extracts determined to be 54.4mg/ml.
The toxicity of various extracts concentrations against white rot and brown rot fungi was tested on agar media and the toxicity threshold determined at 0.024mg/ml of agar for Poria placenta (Pp), Trametes versicolor (Tv), and Gloeplyllum trabeum and 0.049mg/ml for Irpex lacteus.
Extracts at various concentrations above and below the threshold were used to treat aspen blocks at nominal target retentions. Treated blocks were exposed to brown and white rot fungi to determine the biological performance of such treatment. Results showed that extracts retention of 3.9% for brown rot and 8.2% for white rot induced significant durability to aspen blocks treated with padauk extracts. The pitfalls for the transfer of such processes to commercial utilization are also discussed.