Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1957)

Bohus, G. ; Gyarmati, B.: The effects of temperature and pressure on fungi causing wood-decay

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus VIII. Series nova 1957 The Effects of Temperature and Pressure on Fungi Causing Wood-Decay By G. BOHUS and B. GYARMATI, Budapest Theoretical considerations Above temperature maximum, fungi are generally still able to endure a further rise in warmth until the death of the mycelium ensues. At temperature points directly above maximum, the period of thermal toleration is the longer the nearer temperature is to the maximum. The higher the temperature rises, the shorter the time for the perishing of the mycelium is, until, by a further rise in temperature we arrive at the heat-limit, the theoretical thermal death point, where the die off follows in a very short time. Since near temperature limit more and more factors have modifying effects, — causing also certain inconsistencies in the results and conclusions* — we found it necessary to make repetitions and to evaluate results by percentil methods. In the vicinity of temperature limit, diversions in the genetic structure, the age of cultures, the composition of the culture media, indeed, quite fine individual variations all play a modifying role. This is the cause of the somewhat diverging assertions of researches, scanty even today**. Practical aspects The most important methods of the preventive chemical processes for wooden materials — so, e. g. pressure process — have the principal target to delay fungal contamination and the resultant damages. Sortiments (technical wooden materials) of larger cross-sections, or of difficultly saturable woods can, however, not be unifomly protected in their integrity ; there remains usually a rather significant unsaturated portion. If the Sortiments were completely free of infection, the saturated layer would ensure protection until it sustains external injuries. This aseptic state, however, cannot be guaranteed, since wooden materials are, during the months that generally expire from the time of the falling of the tree to the time of the pressure process always and everywhere exposed to contamination. Initial infection cannot always be diagnosed, nor could every material be declared useless because of initial infection. In the saturated portions, preventive chemicals will, naturally, not only inhibit but also destroy all eventually present infection. Saturation could, however, ensure really complete protection only if temperature or pressure conditions of the process would do away with infection in the unsaturated portions too (we disregard the later spreading and long-distance effects of the saturating compound). The aim of our experiments discussed below was to examine our present pressure process methods from this point of view and to contribute new data for the use of processes based on heat effects which are being considered more and more to prohibit and efface fungal contaminations in the built-in wooden materials. * Lee Ling&Emerson H. YU : Thermal death point of fungi in relation to growing conditions (Phytopathology, 31. 1941, p. 264—270). ** L i e s e, J.: Beobachtungen über die Biologie holzzcrstörender Pilze (Angewandte Botanik, 16. 1931. p. 138—150).