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 curculio identify large scars and bumps due to feeding. Most internally damaged fruit (through burrowing into the fruit) drops prematurely. Control of the plum curculio is fairly easy to maintain. Application of proper insecticide during the pink and petal-fall stages of apples, also the petal-fall and shuck-split stages in peaches and cherries is usually enough to reduce plum curculio damage to a minimum. An important preventative measure is destroying the fallen, damaged host fruits before the adults emerge. Pest management at petal fall is also of particular importance. Plum curculio The plum curculio ("Conotrachelus nenuphar") is a true weevil native to