The objectives of this study were to evaluate decay and termite resistance of some tropical hardwood species mainly used in Korea and to confirm the antifungal activities of its extractives. A total of 9 species of tropical hardwood, Apitong, Bankirai...
The objectives of this study were to evaluate decay and termite resistance of some tropical hardwood species mainly used in Korea and to confirm the antifungal activities of its extractives. A total of 9 species of tropical hardwood, Apitong, Bankirai, Burckella, Ipe, Jarrah, Kempas, Keruing, Malas, and Merbau, which were prominently used in Korea were selected and natural durability of the species against to 2 species of brown-rot fungi, Fomitopsis palustris TYP0507 and Gloeophyllum trabeum KUC8067, and 2 species of white-rot fungi, Trametes versicolor COV1030 and Irpex lacteus KUC9013, were investigated. The natural durability test was conducted by soil-block test according to Japanese Industrial Standards JIS K 1571. For comparison purposes, radiata pine sapwood block treated with ACQ-2 which is one of the most frequently used commercial wood preservative in Korea and wood-plastic composite (WPC) block were also included. As a result of soil-block test, Apitong, Bangkirai, Ipe, Jarrah, and Merbau showed the great resistance to decay by the fungal isolates, resulting in weight losses of less than 10%. Of the species, Ipe and Jarrah only showed weight losses of less than 3%. Thus, it is considered that both the 2 species are the most suitable tropical hardwoods which are alternatively used for the preservative-treated wood. ACQ-2-treated wood blocks were remarkably decayed by brown-rot fungi, while WPC showed the notable capacity against to degradation by the fungal isolates used in the present study. It was confirmed that except for Merbau, 8 species of tropical hardwood showed high resistance to termite attack.
In order to evaluate the reason for natural durability of tropical hardwoods, antifungal activities of its extractives were evaluated. Among all species, extractive from Ipe showed the most effective antifungal activities to the fungi used. The result of qualitative analysis of the extractive by liquid chromatography mass spectrometer revealed that lapachol (molecular weight: 242 g/mol) in the extractive might be significantly contributed to outstanding natural durability of Ipe.