A benign viral satellite RNA, in combination with a mild strain of cucumber mosaic virus (CMV-s), was used as a "vaccine" or "preinoculum" to demonstrate the feasibility of protecting pepper (Capsicum annuum cv. california Wonder) and melon (Cucurbita melo cv. Janus des Canaries) against two severe CMV strains, CMV-D and CMV-16 , in the final 2 years of a 4-year pilot field and greenhouse experiment.