Abstract
Feeding aphids on plants infected with carnation etched ring virus (CERV) or figwort mosaic virus (FMV) prior to feeding on plants infected with aphid non-transmissible isolates of cauliflower mosaic virus (CaMV) facilitated transmission. This indicates that CERV and FMV code for aphid transmission factors which can substitute for the defective factors in the non-transmissible CaMV isolates.