Old trees are often killed by the decay fungus Piptoporus betulinus, and the branches often have witch's brooms caused by the fungus Taphrina betulina.
A fungus in the genus Taphrina often attacks the plums; the young ovaries swell, often much larger than full grown plums, become hollow and often persist on the tree in winter.
Taphrina |
Taphrina wiesneri is a plant pathogen causing witch's broom formations on Cherry trees (Prunus & Cerasus sp).