The effect of resistance to Amphorophora rubi in raspberry (Rubus idaeus) on the spread of aphid‐borne viruses

Abstract

SUMMARYThe effectiveness of resistance to the aphid Amphorophora rubi in restricting the spread of aphid‐borne viruses was assessed in a field experiment using six genotypes of red raspberry. In one block of the experiment, the genotypes alternated with rows of virus‐infected Mailing Jewel raspberry, and in the other they alternated with virus‐free Mailing Jewel. During 4 years, the numbers of A. rubi and the amount of 52V virus spread in the two blocks were similar, suggesting that this virus was mostly introduced from outside the plots.Lloyd George and Mailing Jewel raspberry became heavily infested with A. rubi and were rapidly infected with raspberry leaf mottle, raspberry leaf spot and 52V viruses. Glen Clova and Norfolk Giant raspberry, which contain minor genes for resistance to A. rubi, were infested with fewer A. rubi and virus spread more slowly in these cultivars. A. rubi were rare on Mailing Orion and an East Mailing raspberry selection (888/49) which have genes A1 and A10 respectively for resistance to A.rubi, and these plants remained largely free of virus. The role of minor and major gene resistance to A. rubi in restricting virus spread is discussed.A few Macrosiphum euphorbiae and Myzus ornatus were recorded on several of the raspberry genotypes.