Field Evaluation of Promising Local Apple Genotypes for Tolerance to Fungal Canker

Through this investigation 18 promising local apple genotypes along with Gala, Fuji, Red Delicious and Golden Delicious cultivars were evaluated for tolerance to fungal cankers in Kamalshahr horticultural research station, Karaj, Iran, during 2015 and 2016 growing seasons. Preliminary field assessment confirmed the presence of Cytospora. and Neofusicoccum in infected trees. The results showed that the relative susceptibility of genotypes to cytospora chanker was different. H1-SH and T51 genotypes with the average infection score of three were identified as susceptible, B-K-KH together with Fuji cultivar were moderately-susceptible, and SBA genotype and cv. Golden Delicious were identified as low susceptible. Artificial inoculation of Neofusicoccum isolates on dormant excised apple twigs confirmed the pathogenicity of isolates and showed different responses of genotypes to pathogen. Under field conditions, the infection score for sooty canker ranged from zero to three (in MD-N2 genotype). GO-N3, ME6, B-K-KH and SBA genotypes as well as cv. Fuji, cv. Red Delicious and cv. Golden Delicious were grouped as moderately susceptible. Simultaneous infection to both fungal cankers observed on five promising genotypes; T51, SBA, S-O-G, H1-SH and B-K-KH, as well as cv. Golden Delicious and cv. Fuji. It can be concluded that there are invaluable resistance sources among promising local apple genotypes, under natural infection, to be selected and used in apple breeding programs.