Microscopical and Mycological Investigations on Wood of Pendunculate Oak (Quercus robur L) Relative to the Occurrence of Oak Decline

Summary Microscopical studies exhibited great differences between healthy and damaged pendunculate oak trees (Quercus robur L.) relative to the state of sapwood vessels and the degree of fungal infection. In the sapwood of damaged trees deposits, discolorations and early tylosis formations were found which frequently occurred in combination with fungal infections. These results lead to the assumption that the defence reaction of the trees probably induced by fungal infection changes the structure of the tree vessels to such an extent that their water transfer function is disturbed. Some fungal genera playing an important role in the discussion of the causes of oak decline could be isolated.…