Influence of boron in CCB formulation on growth and decay capabilities of copper tolerant fungi

The influence of boron in CCB preservative on infestation of leached and non-leached CCB treated wood specimens by copper tolerant and copper sensitive brown rot decay fungi are described. The tests were performed according the EN 113 procedure using seven different brown rot fungal strains: (Antrodia vaillantii (four different strains), Poria monticola, Gloeophyllum trabeum and Leucogyrophana pinastri). Leaching of boron from the CCB-treated wood samples rendered them susceptible to decay by the copper tolerant strains but not the copper sensitive ones. Additionally, using EPR spectroscopy, non-toxic copper oxalate was found in samples exposed to the copper tolerant strains (A. vaillantii and L. pinastri), as well as the copper sensitive strain P. monticola but not in the samples exposed to the other copper sensitive strain G. trabeum. It is supposed that, in the case of samples that were not leached before exposure to the copper tolerant fungi fungal growth and decay were inhibited by boron.