On the stem and on branches of living trees fruiting structures appear commonly at the stem base or in tree cavities: grey, powdery, later black crusts. The grey stage (asexual form) is very characteristic in spring, the black (coal-like) crusts not (can be mistaken for other fungi). In the crown sometimes dying of branches, but often the crown doesn't show any symptoms at all!
Affected tree species
Beech; Elm; Horse chestnut; Linden, Lime; Plane;
The carbon cushion belongs to the most dangerous destructive fungi, since it causes an intense white rot in the wood, which reduces markedly the stability of the tree. Thus, without any signs in the crown, old trees can suddenly break. The fungus often enters the roots through wounds subsequently growing towards the stem. Linden trees are especially endangered, but also beeches and other broadleaved trees can be attacked.
Curative measures After a clear diagnosis by identification of the fruiting structures, a check of the stability of the tree has to follow quickly, using technical (pulling) methods. Thus, if the high risk of breakage is proved, felling can be done at the right time.