Evaluation of Gliocladium roseum against wood-degrading fungi in vitro and on major Canadian wood species

The protection of wood from fungal stain using biological agents has considerable potential for reducing discoloration of freshly sawn logs and lumber, while decreasing fungicide use A number of biocontrol candidates have been reported worldwide, and Gliocladium roseum is one of such microorganisms. In this study, the bio-activity of G. roseum was investigated against different wood-degrading fungi on agar plates and wafers of 12 major Canadian,rood species. Of the four sap-staining fungi tested on agar plates, Ophiostoma piceae and Alternaria alternata showed greater sensitivity than Aureobasidium pullulans or Cladosporium sphaero-spermum to G. roseum. On wood wafers, a spore suspension of G. roseum (1 x 10(6) spores/ml) provided satisfactory protection of wood from stain on western hemlock (Tsuga heterophylla), white spruce (Picea glauca), amabilis fir (Abies amabilis), balsam fir (Abies balsamea) and jack pine (Pinus banksiana). The antagonist also restricted the development of moulds and stain on black spruce (Picea mariana), lodgepole pine (Pinus contorts) and white pine (Pinus strobus), but did not protect Douglas fir (Pseudotsuga menziesii), red pine (Pinus resinosa), white birch (Betula papyrifera) and trembling aspen (Populus tremuloides). Logs of black spruce and jack pine treated with G. roseum were much less stained than untreated ones after a 4-month period of summer storage in the field. In an anti-decay test, no significant difference was found for weight loss between wood blocks treated with G. roseum and untreated samples. Application of G. roseum with low levels of an anti-sap stain chemical (NP-1) to wood wafers simultaneously did not produce a noticeable improvement in wood protection against stain compared with the chemical treatment alone.