Among the volatile organic compounds which are produced by fungi（FVOCs）, there are compounds showing biological activity, and it has been suggested that they function as signaling molecules, “infochemicals”, in biological interactions through the biological activity. In the present study, we aimed to obtain information on the roles of FVOCs in the interaction between wood decay fungi. As a first step, we investigated the biological activity of FVOCs produced by wood decay fungi, using mycelial growth as an indicator. Seven species of wood decay fungi were exposed to 13 FVOCs, and only 2,5-dimethylfuran showed strong inhibitory activity against all tested species. The responses to the other FVOCs were different among the species. Furthermore, the effects of FVOCs-concentrations on mycelial growth were investigated in Gloeophyllum trabeum and Ganoderma mastoporum using six eight-carbon FVOCs. The results showed that the effect of FVOCs on mycelial growth depended on the concentrations of FVOCs. These results indicate that wood decay fungi could recognize different FVOCs compounds, and that the susceptibility to FVOCs varies among species.

The development of utilization technologies for cross-laminated timber in the civil engineering field is being promoted as a national policy to expand its demand in Japan. In this study, post-fabrication treatment of CLT using creosote oil or copper naphthenate, which have been used for railway sleeper treatment, was investigated for use as bridge slabs. Heartwood laminae of Japanese cedar（Cryptomeria japonica）, Sakhalin fir（Abies sachalinensis）, or Japanese larch（Larix kaempferi）were used for the fabrication of 3-ply CLT specimens（90mm✕420mm✕800mm）. The wide face of each outer layer lamina was incised before fabrication to achieve uniform penetration of the preservatives. The solution uptake of copper naphthenate and creosote oil by pressure treatment was similar, with both showing greater uptake in the following order: Japanese cedar > Sakhalin fir >Japanese larch. The penetration ratios of copper naphthenate were higher than those of creosote oil, achieving nearly 100% penetration in the cross-grain area of the middle part of CLT specimens made from Japanese cedar and Sakhalin fir. In Sakhalin fir, where liquid penetration in the heartwood is difficult, and in Japanese larch, where it is extremely difficult, there was a substantial difference in the penetration levels between NCU-O and creosote oil. Although it was difficult for the preservatives to penetrate the inner layers by soaking or painting, copper naphthenate could penetrate as deeply as pressure treatment, up to 10mm from the surface of Japanese cedar CLT specimens. Additionally, it was considered that none of the treatments had a significant impact on the initial adhesive performance of CLT.

High dimensional stability and stable treated performance have been demanded of preservative treated wood in recent years. In this study, the performance of a new preservative, “Mokubo HP” developed for low-pressure spray treatment was evaluated for decay and termite resistance. Incised Japanese cypress（Chamaecyparis obtuse Endl.）lumber, Douglas fir（Pseudotsuga menziesii）lumber, and laminated Scots pine（Pinus sylvestris）were sprayed with “Mokubo HP” diluted solution（0.37％ hexaconazole and 0.43％ permethrin）at a pressure of 0.5MPa on four faces of the specimens using a power sprayer. As a result, it was confirmed that a certain amount of uptake（400g/m² or more）met the degree of penetration designated in the AQ certification criteria by Japan Housing and Wood Technology Center. The measurement of the absorption distribution from the surface to 10mm depth showed that the two active ingredients penetrated in equal proportions. Decay and termite resistance tests both in laboratory and field were conducted in accordance with JIS K 1571 ： 2010. In the laboratory decay test, the mean mass loss of samples at a hexaconazole absorption rate of 0.11kg/m³ or more was 0％ by the degradation of Fomitopsis palustris and Trametes versicolor. The laboratory termite test showed the mean mass loss of samples at a permethrin absorption rate of 0.12kg/m³ or more was 0％ by the degradation of Coptotermes formosanus. Both in the field test and fungus cellar test specified in JIS K 1571 ： 2010, the performance standard of the JIS was satisfied with treated stakes at these absorption levels. These results indicate that “Mokubo HP” has sufficient performance as a wood preservative for surface treatment（oil soluble）- deep penetration certified by the Japan Wood Protection Association.