AbstractAfter graft inoculation with RYNV, 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cultivars were graft-inoculated with RYNV and 3 other aphid-borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leafspot, singly and in all combinations. In periods of up to 4 years, classical veinbanding mosaic symptoms developed in sensitive cultivars only when they contained both RYNV and RLMV. These symptoms were intensified in plants co-infected with additional viruses. Veinbinding mosaic disease did not develop in any of 11 cultivars infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.