Sooty-Bark disease of Maples (Cryptostroma corticale)
Symptome / Baumarten
Bedeutung / Maßnahmen
Maples (Acer sp., mostly Acer pseudoplatanus) with wilting crowns or dieback. Detachment of the stem bark initially in form of rectangular areas, later on long and broad black stripes. The stripes consist of thick layers of microscopic fungal spores, which are dispersed by wind. In case of rain they are washed down from the stem to produce a blackish stained area around the stem base. In cross section the wood of the stem show a greenish, yellowish or brownish stain, which is, however, not specific for Cryptostroma. Where the discolored area reaches the bark, the spore bearing structures develop. Dead trees loose their stain in the wood, or it is replaced by rot-stain. If the spores are present, there are hardly possibilites for errors in diagnosis.
Sooty bark disease of maples is a characteristic consequence of long and extraordinary warm summers. Only after a long period with permanently warm temperatures the fungus, which is often present in the wood without causing symptoms there, is able to start its growth from the heart-wood towards the bark. the disease is common in Northern America and in Europe in mild climates in the West, as well as locally in the Mediterranean area. Because of the extreme high number of spores there is a medical risk for people working in the forest close to diseased trees ("bark strippers lung").
Kurative Maßnahmen Diseased trees can not be saved. They should be removed for the medical reasons mentionned above.