Changes in Weight Loss and Dimensions of Wood Infected with Brown-Rot Fungi

This paper reports on the relation of abnormal shrinkage on drying of red oak heartwood and southern pine sapwood to loss in weight caused by infection by two brown-rot fungi. The ASTM standard soil-block decay test was used. Lenzites trabea Fr. (Madison isolate 617) was used to inoculate red oak blocks, which were incubated in test bottles for ten weeks at 26.7?C. and 70 percent relative humidity. Poria monticola Murr. (Madison isolate 698) was used to inoculate pine blocks. Red oak heartwood decayed by the brown-rot fungus, Lenzites trabea, shrank in the tangential direction from 0 to 24 percent (ave. 5 percent) more than undecayed blocks when dried to constant weight at 26.7?C. and 70 percent relative humidity. Weight loss varied from 60 to 69 percent (ave. 40 percent). As tangential shrinkage increased weight loss increased. Southern pine sapwood decayed by the brown-rot fungus, Poria monticola, shrank, in the tangential direction from 0 to 31 percent (ave. 14 percent) and in the radial direction from 2 to 23 percent (ave. 12 percent) more than undecayed blocks when dried to constant weight at 26.7?C. and 70 percent relative humidity; weight loss varied from 11 to 65 percent (ave. 48 percent). These data on shrinkage can be used to predict higher weight losses, but would not be useful in detecting the threshold in preservative tests.

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