Evaluation of the tolerance to the rosy apple aphid, Dysaphis plantaginea (Pass.), in descendants of the crossing ‘Raxao’ x ‘Florina’

Abstract

In a cider apple breeding programme the susceptible local cv ‘Raxao’ and the cv ‘Florina’, resistant to the rosy apple aphid, Dysaphis plantaginea (Pass.) (Homoptera: Aphididae), have been crossed. Thirty-four hybrids have been previously selected for their resistance to apple scab and low susceptibility to powdery mildew. The results of the tolerance to D. plantaginea of those 34 descendants are reported. The progeny was tested in controlled conditions after infestation with aptera and in the field after natural colonisation. In the greenhouse test, 44.1 % of the assessed cultivars did not show the typical D. plantaginea deformations and were considered as tolerant cultivars. Among the other 55.9 %, the deformation level was of different importance. The male parent and resistant control cv ‘Florina’ did not show symptoms and the susceptible control cv ‘Golden Delicious’ was the most damaged cultivar. The female parent cv ‘Raxao’ was also susceptible to D. plantaginea. In the field trials, only 38.2 % of the hybrids showed D. plantaginea deformations. The cultivars which showed deformations in the field were also susceptible in the greenhouse conditions, and the cultivars considered as tolerant in the greenhouse did not show deformations in the field trials. The results show clearly that cv ‘Florina’ is a good parent for the transmission of the tolerance to D. plantaginea. The present study takes another step in offering the grower new cultivars with interesting technological and agronomical implications, such as resistance to pests and diseases, which is considered to be a powerful tool in pest management programs.