Differential virulence of Xanthomonas campestris pv. pruni to peach, plum, and apricot cultivars

Virulence of five strains of Xanthomonas campestris pv. pruni to 10 peach, plum, and apricot cultivars was determined after inoculation of detached leaves and leaves on trees in a greenhouse. Virulence of these five strains and 10 additional strains of X. c. pruni to four peach cultivars was also measured on detached leaves. A highly significant interaction occurred between strains and cultivars. Differential virulence exhibited by X. c. pruni strain Xcp2 on detached leaves of plum cultivars Golden King, Reubennel, and Songold corresponded to results obtained in the greenhouse. However, the differential virulence of strain Xcp2 to Royal apricot in the greenhouse was not apparent on detached leaves. Some strains of X. c. pruni were differentially virulent to detached leaves of peach cultivars Olympia, Bokkeveld, and Hantam