INCIDENCE OF RASPBERRY BUSHY DWARF VIRUS IN BREEDING PLOTS OF RED RASPBERRY

More than 300 red raspberry cultivars and selections were screened for raspberry (Rubus idaeus L.) bushy dwarf virus (RBDV), tobacco streak virus (TSV), and tomato ringspot virus (TomRSV) using enzyme-linked im munosorbent assay in three naturally infected breeding program selecti on plots at Corvallis, Ore. All genotypes tested negative for TSV and TomRSV, The RBDV incidence in primocane-fruiting cultivars and selecti ons was 67%; in floricane-fruiting genotypes, it was 34%. The pattern of RBDV infection in the field showed no discernible trend. The high i ncidence may have been due to use of infected parents, propagation of infected genotypes, and pollen transmission, 'Willamette', considered to be immune to the common strain of RBDV, along with 14 clones that h ad been in the field 10 years or longer, tested negative. The high inc idence of RBDV in the breeding plots may provide an opportunity to ide ntify resistant parents for breeding programs. An early seedling scree ning method for RBDV susceptibility is desirable to eliminate highly s usceptible genotypes from the program and maintain a lower incidence o f RBDV within the breeding plots.