Susceptibility of sweet and sour cherry cultivars/genotypes to feeding damage caused by Bryobia rubrioculus (Acari: Tetranychidae)

The sweet cherry Prunus avium L. and sour cherry Prunus cerasus L. are considered important fruit trees, providing valuable and delicious fruit worldwide. We compared the susceptibility of 10 cultivars of sweet cherry and 5 genotypes of sour cherry to Bryobia rubrioculus Scheuten feeding by manually counting brown spots and by measuring damaged leaf area using a computerized image analysis technique. Damaged leaves were individually scanned on a common flatbed color scanner on a white background. The cultivars and genotypes of sweet and sour cherries, based on the mean area percentage having feeding symptoms on the leaves, were classified into three groups: (1) "susceptible", i.e., Hamedan, BN 5150, BT 5148, Zard-90, KB 9 and KB 10; (2) "semi-resistant", i.e., KB 21, Sabima, BT 5124, KB 25 and Lambert; and (3) "resistant", i.e., Haj Yousefi, BO 5187, BT 5154 and Siah Mashhad. A corresponding increase in the mean value of the symptom area was observed as the number of adult brown mites increased per disc. The results of both methods were compared, and the advantages of each method were discussed.