A complex of insect species, including the green apple aphid, the rosy apple aphid, and the woolly apple aphid, which cause leaf deformation, gall formation, and tissue damage to the trunk and roots.
In the reference
44
varieties
crop Apple,
where this is mentioned in the description.
Three main species of aphids are identified on apple trees. The green apple aphid is a non-migratory pest that feeds on shoots, causing them to curl. The rosy apple aphid forms specific red or yellow swellings on the leaves. The woolly apple aphid is distinguished by a waxy coating and infests the bark and roots, contributing to the formation of painful outgrowths known as galls.
The interaction between the pest and the crop is characterized by the presence of biotypes, such as the 1st and 2nd biotypes of the rosy apple aphid, to which varietal resistance may be shown. Breeding research is focused on identifying sources of resistance to the woolly apple aphid, among which the Northern Spy cultivar is known; however, the generally accepted nomenclature for resistance genes in this group of pests is less formalized than in the case of fungal diseases.
General information about the subject — on the page
Aphids.
Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.