The anamorphic fungus Fusicoccum quercus Oudem. (form-genus Coelomycetes, Deuteromycotina) is frequently distributed in cultures of sessile, pedunculate, and red oak and causes bark necrosis on young plants as well as twig dieback on adult trees in forest stands. The incidence of F. quercus is supported by sandy soils with low water capacity and drought periods especially in spring. The description of the morphology and the epidemiology of the pathogen is given by Butin 1981.
Stronger damage was observed subsequent to the afforestation of former arable areas with pure cultures of oak and broadleaf mixtures with an oak species in the north-east of Germany. In the case of severe extend of damage the whole culture was dying-off in the course of two years and was renewed by another tree species. With milder disease incidence a dieback of the terminal shoot could be observed immediately followed by a bushy growth habit of the plants.
In this work a collection of fungal strains originating from three oak host species with different age were compared regarding their diversity in vitro and their virulence causing necrosis on oak plantlets.