The wood preservative potentials of heartwood extracts of Milicia excelsa and Erythrophleum suaveolens

Abstract The ability of heartwood extracts of two very durable tropical hardwood species ( Milicia excelsa (Welw.) C.C. Berg. Syn Chlorophora excelsa (Welw.) and Erythrophelum suaveolens (Guill. & Perr.) Brenan Syn Erythrophleum guinensis ) to suppress attack by Lenzites trabea (a brown rotter) or by Polyporous versicolor (a white rotter) was investigated. Air dry extracts were dissolved in 60% methanol and impregnated into sapwood blocks of Ceiba pentandra Gaertn. Extract dosages were 8.009, 24.778, 48.056 and 96.11 kg/m 3 (0.5, 1.5, 3.0 and 6.0 lb/ft 3 ). Treated blocks were exposed to L. trabea and P. versicolor attack for 14 weeks by the soil block method using the procedure set out in ASTM D 1413-72. Only extract dosages of 48.056 and 96.11 kg/m 3 (3.0 and 6.0 lb/ft 3 ) were found efficacious in suppressing fungal attack. A tukey studentized test found both dosages significant at 1% level.