Ekki heartwood - is “Durable”

Severe decay damages of bridges made of ekki (Lophira alata Banks) wood which is classified as a durable species in the EN 350:2 as already reported at the 31 IRG annual meeting. This paper deals with results of long-term decay tests of ekki heartwood specimens using 3 isolates (Loweporus tephroporus 2 strains and a fungus of other sp. from damaged ekki bridges) and Trametes versicolor as a reference. Sound ekki heartwood specimens, sized 20(T) x 20(R) x 5(L) mm were used. References were Japanese beech (Fagus crenata) specimens having the same dimensions. Oven dry weights of the specimens were measured at 60 oC for 48 h before and after the decay process. Nine replications of specimens were used per set. The procedure of decay test was about the same as that of the JIS Z 2101. All the test fungi including T versicolor decayed ekki heartwood in the case of long-term exposure (more than 6 months) using the appropriate nutritional condition under optimum temperatures. These facts suggest that the results of standardised decay test methods should be carefully interpreted.