Differential Susceptibility of Malus spp. Cultivars Robusta 5, Novole, and Ottawa 523 to Erwinia amylovora. J. L. Norelli, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456-0462. H. S. Aldwinckle, Department of Plant Pathology, Cornell University, New York State Agricultural Experiment Station, Geneva 14456-0462, and S. V. Beer, Department of Plant Pathology, Cornell University, Ithaca, NY 14853-0331. Plant Dis. 70:1017-1019. Accepted for publication 2 June 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1017.

Twenty-five apple cultivars were inoculated with two strains of E. amylovora to evaluate their fire blight susceptibility. Three cultivars were highly resistant to strain Ea 273 but were susceptible to strain Ea 266. These included Robusta 5 and Novole, which were previously identified as fire blight-resistant, and Ottawa 523. The data indicate these cultivars are differentially susceptible to strain Ea 266.