Abstract
English sources of viruses causing star crack and russet ring were grafted to nine apple varieties. Only Golden Delicious reacted to all virus sources. This variety differentiated most clearly between different sources of star crack inoculum. Cox’s Orange Pippin and Spartan reacted to all star crack sources; Belle de Boskoop, Weisser Winterglocken, Lord Lambourne, Laxton’s Fortune and Worcester Pearmain reacted when inoculated with some sources but not others, while Granny Smith reacted to none. Golden Delicious developed leaf and fruit symptoms when inoculated with russet ring viruses, but Cox’s Orange Pippin, Spartan, Belle de Boskoop, Weisser Winterglocken and Granny Smith did not. Mailing II rootstocks developed characteristic leaf symptoms when infected with russet ring viruses. One inoculation source caused leaf mottling and necrosis and russeted warts on the fruits of Golden Delicious and Cox’s Orange Pippin. A rough-skin condition of Belle de Boskoop was perpetuated by buds and grafts but not transmitted. Some of the English viruses caused symptoms, in certain varieties, indistinguishable from diseases reported from Germany, Switzerland, the Netherlands, and North America.

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