Studies in the genus Ustulina with special reference to Parasitism : V. A disease of elm ( Ulmus campestris sm.) caused by Ustulina

Abstract

1. A diseased elm was investigated with the object of showing that Ustulina was responsible for the disease, and of continuing an attempt to establish the status of this fungus as a pathogen of timber trees in temperate regions. 2. The causal organism was isolated and found to be solely Ustulina . This was confirmed by reinfection and subsequent reisolation. 3. The stem and roots of the tree were sectioned and examined to determine the nature and extent of the disease. 4. Microscopic examination of the wood showed that the type of disintegration of the wood elements compared closely with that of the lime and that the final result of decay was almost identical in both. 5. The distribution of the mycelium and hyphal penetration is briefly commented on. 6. This elm disease is compared with the lime disease and it is concluded that Ustulina vulgaris is capable of causing a white rot of elm.