Response of Apple Scions on Size-Controlling Rootstocks to Inoculation by Erwinia amylovora. W. G. Bonn, Research Station, Agriculture Canada, Harrow, Ontario NOR 1G0. V. A. Dirks, Research Station, Agriculture Canada, Harrow, Ontario NOR 1G0. Plant Dis. 64:209-211. Accepted for publication 7 October 1979. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-209.

Controlled inoculation studies in the field at the Harrow Research Station in southwestern Ontario during two successive seasons showed that the size-controlling apple rootstocks M26, MM106, and MM111 did not greatly influence the fire blight susceptibility of several popular scions grafted onto them. The interaction between scion cultivar and rootstock was not large enough to overcome the strong influence of the cultivar on the fire blight susceptibility of young trees.