Development of model systems for investigations of the dry rot fungus Serpula lacrymans (Schumach. ex Fr.) Gray: Use for analysis of the environmental sensitivity of the organism

Novel microcosms were used to test separately the effects of aeration and h umidity on the decay capacity, linear spread and survival of the dry rot fu ngus Serpula lacrymans. The application of a pumped air supply resulted in cessation of fungal activity in the microcosms at all but the lowest air fl ow rate. At this lowest rate marked growth tropisms were sometimes seen and linear growth of the fungus away from the air supply was accentuated. In b oth air flow and humidity experiments the loss of growth and decay capabili ties was not always accompanied by a loss of viability. Larger scale growth chambers incorporating simulated flooring and plaster walling were develop ed in sealed aquarium tanks using both new and old building materials. Diff erences in growth rates and morphology of S. lacrymans were noted, with old materials generally being more favorable to the growth of the organism. Op ening the growth chambers and applying a controlled air flow rapidly halted the spread of S. lacrymans resulting in the fungal mycelium shrivelling, d iscolouring and becoming susceptible to attack by moulds. Loss of viability of S. lacrymans in re-sealed chambers depended crucially on the instigatio n of a water-deprivation schedule. The results may have serious implication s for the use of purely environmental strategies for the remedial treatment of outbreaks of the dry rot fungus in buildings.