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 americana Prunus americana Prunus americana, commonly called the American plum, wild plum, or Marshall's large yellow sweet plum, is a species of "Prunus" native to North America from Saskatchewan and Idaho south to New Mexico and east to Québec, Maine and Florida. "Prunus americana" has often been planted outside its native range and sometimes escapes cultivation. It is commonly confused with the Canada plum ("Prunus nigra"), although the fruit is smaller and rounder and bright red as opposed to yellow. Many cultivated varieties have been derived from this species. It forms an excellent stock upon which to graft the domestic plum.