RESISTANCE TO DRY ROT

Evening Star, Issue 21638, 6 February 1934, Page 2

RESISTANCE TO DRY ROT

TESTS Of CANADIAN WOOD RESEARCH IN ENGLAND The danger that a Japanese timber pest may become established in England is referred to in the annual report of the Forest Products Research Hoard, issued by the .Department of Scientific and Industrial Research. The discovery of Empire timbers which resist dry rot and of the conditions that favour the attacks of death-watch beetles in roof timbers are other subjects dealt with (says a writer in the ‘ Manchester Guardian ’). A variety of the Lyctus powderpost beetle new to this country has been detected in imported Japanese oak, and there is a real danger, the report states, that this now variety may become established in timberyards and manufacturers’ premises in this country. “ Although there is ample evidence,” the report continues, “ of continued losses to the hardwood trade from damage caused by Lyctus powder-post beetles, there has been as yet no organised campaign by the industries concerned to deal with the problem. Many industrial concerns have sought advice from the laboratory and have put its recommendations into practice. Until, however, there is a more united effort on the part of timber merchants and importers on the one hand and manufacturers on the other there is little hope of material reduction of this type of damage to timber.” RESULTS OF EXPERIMENTS, The existence of two Empire timbers callable of offering a stout resistance to attack by dry rot is referred to in descriptions of tests made in the experimental building recently constructed at. the Forest Products Rc- . search Laboratory, Princes Risborough.

specially for the investigation of wooddestroying fungi and beetles. The building contains rooms of good and bad construction. ,fn the “ had construction ” room, in which there is a hollow floor with no ventilation beneath it, fungus lias covered the greater part of the flooring eighteen months after inoculation. Alternate hoards were removed from the floor of this room when the fungus was in active growth, mid were replaced by hoards of western red cedar and of western hemlock, both Canadian timbers. After nine months there were slight signs of attack upon the hemlock, but the red cedar boards were completely free from fungus. “ No growth of fungus took place,’’ the report states, “ in the ‘ good construction ’ room, where there is adequate ventilation under the floor, although each section of the floor has been twice infected with wood on which dry rot fungus was in active growth. This demonstrates that good ventilation will prevent the outbreak of dry rot even if infection be present. It does not moan that a wellrcstablishcd attack by ‘ Merulius ’ (the dry-rot fungus) can ho checked by ventilation alone, but that an outbreak will not or igiuate in a well-ventilated floor.” DEATH-WATCH BEETLES. More than JOO inquiries received ai the laboratory referred to' damage n. limber by attack by beetles. The majority of' these related to damage In death-watch, furniture, and powder post beetles. There was still difficult.' in obtaining live specimens of deathwatch beetles for experimental work but this bad been partially overcome b. obtaining two willow trees known t contain the living insects and replan! ing them in the ground of the labora tory. “ As a result of the work of p;< vious years,” the report mentions, ” i has been possible to reproduce in f laboratory conditions in timber whic have proved more suitable for the d< velopment of the early stages o. Xcstohium (death-watch beetle) lame than those hitherto investigated. Consequently it has hccii found that larva* feeding in timber in which these con-

1 itions —chiefly by humidity and the presence of decay produced by fungi—iccur have been making much more rapid progress in their development han larva) which have been under hsorvation for two years under other auditions. “ Temperature has been shown to ■ve an important effect on the rate ol ■velopment of the insect, particularly i conjunction with other requisite cqn’Lions within the timber.” An inrease in temperature within certain units results in a marked reducton i the incubation period and thereby hastened the rate of development of the insect.