Differential host × pathogen interactions among cultivars of apple and strains of Erwinia amylovora.
In orchard tests with 19 E. amylovora strs. during 2 growing seasons on several apple cultivars, there was a significant cultivar × str. interaction. Virulence of str. 266 to Quinte apple plants varied in both seasons. Greenhouse tests confirmed the differential virulence of this str. for Quinte.