CCB treated wood is generally resistant to all wood decay fungi. However, like CCA impregnated wood, susceptibility of CCB treated wood to copper tolerant fungi have been observed. The ability of various brown rot fungal hyphae to penetrate and overgrow the wood samples was investigated. Samples made of Norway spruce (Picea abies) were impregnated with 5 % CCB solution according to the EN 113 procedure. After conditioning, part of the samples was leached according to the EN 84 method. Small stick of unimpregnated wood (r = 1.5 mm, l = 25 mm) was inserted into a hole, bored in the center of the samples, and after that sealed with epoxy coating. Sterilized, leached and non-leached impregnated and unimpregnated specimens were exposed to two copper-tolerant (Antrodia vaillantii, Leucogyrophana pinastri) and two copper sensitive (Poria monticola, Gloeophyllum trabeum) brown rot fungi for one, two or four weeks. After exposure, the inserted wood pieces were removed from the specimens and put onto nutrient medium in petri dishes. Growth of the hyphae from those wood pieces was then visually determined. Rate of colonization by the fungi were determined by measurement of CO2 production. After that, mass losses of parallel specimens were also determined. The fastest colonization of the unimpregnated specimens was by G. trabeum (one week). On the other hand, no fungal growth could be detected on non-leached CCB impregnated specimens even after four weeks of exposure. However, significantly more intense colonization by the copper tolerant fungi were detected on the leached CCB treated samples.

Download document (300 kb)
free for the members of IRG. Available if purchased.

Purchase this document