Plum pox show no symptoms on leaves or fruit. Not all infection in "Prunus" are characterized by a ring symptom on leaves. Several cultivars show yellowing line patterns and blotches, or necrotic ring symptoms on expanded leaves. Leaf distortion has also been observed. Infected fruit can develop yellow rings or blotches, or brown rings, and some plum and apricot fruit can be severely deformed and bumpy. The seed of many infected apricots and some plums show rings. Many non-"Prunus" species, in at least nine plant families, have been infected artificially with one or more strains of the plum pox virus, and in
Plum cake to as "Pflaumenkuchen" or "Zwetschgenkuchen". Other plum-based cakes are found in French, Italian and Polish cooking. The term "plum cake" and "fruit cake" have become interchangeable. Since dried fruit is used as a sweetening agent and any dried fruit used to be described as "plums", many plum cakes and plum puddings do not contain the plum fruit now known by that name. (Plum pudding is a similar, richer dish prepared with similar ingredients, cooked by steaming the mixture rather than baking it.) The term "plum" originally referred to prunes, raisins or grapes. Thus the so-called plums from which English plum