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

Abstract

Summary Novel microcosms were used to test separately the effects of aeration and humidity on the decay capacity, linear spread and survival of the dry rot fungus Serpula lacrymans. The application of a pumped air supply resulted in cessation of fungal activity in the microcosms at all but the lowest air flow 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 both air flow and humidity experiments the loss of growth and decay capabilities was not always accompanied by a loss of viability. Larger scale growth chambers incorporating simulated flooring and plaster walling were developed in sealed aquarium tanks using both new and old building materials. Differences in growth rates and morphology of S. lacrymans were noted, with old materials generally being more favorable to the growth of the organism. Opening the growth chambers and applying a controlled air flow rapidly halted the spread of S. lacrymans resulting in the fungal mycelium shrivelling, discolouring and becoming susceptible to attack by moulds. Loss of viability of S. lacrymans in re-sealed chambers depended crucially on the instigation of a water-deprivation schedule. The results may have serious implications for the use of purely environmental strategies for the remedial treatment of outbreaks of the dry rot fungus in buildings.