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
Boy Peeling Fruit (Caravaggio) the "Young Sick Bacchus" and the "Boy with a Basket of Fruit". It is not known how these works came to be in Cesari's collection at the time. The fruit being peeled by the boy is something of a mystery. Sources indicate it may be a pear, which is probably correct but has been questioned; it may be a nectarine or plum, several of which lie on the table, but these are not usually peeled; some have suggested a bergamot, a pear-shaped citrus fruit grown in Italy, but others object that the bergamot is sour and practically inedible. Seen as