Further studies on seed transmission in the ecology of some aphid-transmitted viruses

A small proportion (1–4%) of the seeds of Stellaria media extracted from fallow soil from three widely separated areas contained cucumber mosaic virus (CMV). S. media seeds buried for 21 months produced 5 % infected seedlings. S. media plants from Britain, N. America and Australia were least severely affected by the CMV strain obtained from their country of origin and showed more severe reactions when infected with two alien strains. Several weed species were experimentally infected with lettuce mosaic, turnip mosaic and cauliflower mosaic viruses but, although virus was detected in the seeds of some species, it was not transmitted to any of their seedlings.