Abstract

The rate of spread of viruses (including black raspberry necrosis virus (BRNV), raspberry leaf spot virus and raspberry veinbanding mosaic disease) transmitted by Amphorophora idaei (Born.) to raspberry genotypes having different levels of resistance to the aphid was determined in a field experiment in Scotland in 1971-78 in which plants were exposed to large numbers of infective aphids. Under these conditions, genotypes readily colonised by A. idaei were totally infected with virus after 2-3 growing seasons, whereas genotypes with a high degree of resistance were substantially free of virus after 4 growing seasons though 56% of plants were infected after 7 seasons. Genotypes with intermediate resistance were also substantially free of virus after 3 seasons but 76% of plants were infected after 7 seasons.
The effectiveness of resistance to A. idaei in raspberry in restricting the spread of viruses transmitted by the aphid is discussed.