SATELLITE-MEDIATED PROTECTION OF TOMATO AGAINST CUCUMBER MOSAIC-VIRUS .1. GREENHOUSE EXPERIMENTS AND SIMULATED EPIDEMIC CONDITIONS IN THE FIELD

Cucumber mosaic virus (CMV) strain S, with its naturally occuring satellite, can be used as a biological control agent to protect tomato (Lycopersicon esculentum 'UC82B') plants against disease induced by two severe CMV strains (D and 16). In greenhouse experiments, tomato plants were preinoculated or "vaccinated" with total RNA extracted from CMV-S and when challenge-inoculated after 3 wk with the severe strains, were protected against their effects. No synergistic effects were observed in mixed infections of CMV-S and a number of viruses commonly infecting tomato. Satellite-mediated protection was more protective and could be established sooner after vaccination than conventional cross-protection. In field studies, the fruit yield from protected and challenge-inoculated plants was double that of similarly challenged but not protected plants, whether the challenge was applied mechanically or by aphids.