Taphrina pruni being larger than the healthy one. As a fungus, cool and wet weather conditions promote the germination of spores, whilst warm and dry weather results in infection rarely taking place. Colonisation can become extensive and eradication very difficult. The disease can to some degree be controlled by carefully removing infected branches, witch's brooms and fruit before the infective air borne spores are produced. Applications of copper-containing fungicides have a degree of control over the fungus. Taphrina pruni Taphrina pruni is a fungal plant pathogen of blackthorn (Prunus spinosa) that causes the Pocket or bladder Plum gall, a chemically induced distortion
Prunus cerasus Belgium. Prunus cerasus Prunus cerasus (sour cherry, tart cherry, or dwarf cherry) is a species of "Prunus" in the subgenus "Cerasus" (cherries), native to much of Europe and southwest Asia. It is closely related to the sweet cherry ("Prunus avium"), but has a fruit that is more acidic. The tree is smaller than the sweet cherry (growing to a height of 4–10 m), has twiggy branches, and its crimson-to-near-black cherries are borne upon shorter stalks. There are several varieties of the sour cherry: the dark-red morello cherry and the lighter-red varieties including the amarelle cherry, and the popular Montmorency cherry.