Taphrina pruni 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 of the fruit (sloes), producing swollen on one side, otherwise deformed and flattened fruit gall without a stone. The twigs on infected plants may also be deformed with small strap-shaped leaves. "T. pruni" produces a distinctive tongue-like growth, similar to other closely related species such as "Taphrina alni" on Alder ("Alnus glutinosa") and "Taphrina padi" on Bird Cherry "Prunus padus". The growth is the distorted fruit and not a fungus in its entirety. "T. pruni"
Prunus avium in classical schools, it must once more be said that cherry trees (at least the bird cherry) existed in Italy before Lucullus, and that the famous gourmet did not need to go far to seek the species with the sour or bitter fruit. De Candolle suggests that what Lucullus brought back was a particular cultivar of "Prunus avium" from the Caucasus. The origin of cultivars of "P. avium" is still an open question. Modern cultivated cherries differ from wild ones in having larger fruit, 2–3 cm diameter. The trees are often grown on dwarfing rootstocks to keep them smaller for