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Damage by voles has continued to be a major cause of tree mortality American orchards despite nearly universal use of herbicides and rodenticide. (1,7). To reduce damage done by voles in infested orchards, one valuable tool could be use of a stock system that voles found highly unattractive. Having such stock systems in place would be particularly valuable during periods when the orchardist could neither bait nor spray for control.
A cooperative VPI/Cornell research project initiated in 1974 identified a few cultivars with relatively high levels of resistance to pine voles, as expressed in free-choice tests under laboratory conditions. This work also provided data suggesting that such resistances to pine vole were simple inherited in Malus(2.6).
Apple growers have long held that certain cultivars were attacked preferentially by meadow voles; 'Hibernal' and Mailing 9 (M.9) have been reported to be especially severely attacked. We initiated the study reported here to determine whether Malus clones consistently rejected by pine voles in free-choice situations in the Winchester laboratory tests would be similarly rejected by meadow voles under orchard conditions at Geneva.