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 currants were used, which in the English language were referred to as plums since around 1660. The various types of dried fruit (grapes, currants and raisins) were familiar to English kitchens through trade with The Levant and Mediterranean but before they became available through "trouble-free" imports from Australia, South Africa and California, preparing them required "an immense amount of labour ... on account of the rough and ready methods by which the fruit was picked, dried, packed and exported". In 1881 Colonel Henry-Herbert said that "a good English plum cake...is a national institution". At times, Thomas Carlyle was one among