Symptoms on foliage

The most frequent symptoms on potato plants are mosaic patterns and leaf deformation of the apical leaflets. Blisters on the foliage have also been described. Bright yellow spots are often observed with secondary infections (photo 1). Yellowing extends to the petioles and to the leaves which hang down along the stems. Often, the virus can only be detected in those parts of the plant that show symptoms. The virus often causes plant dwarfing.

In 1984, in California (USA), a local outbreak of the disease occurred on potato cultivars White Rose and Red La Soda. 60 to 100% of the plants were infected and showed symptoms of mosaic, apical deformation, necrosis, dwarfism and early maturity. 95% of the tubers were not marketable due to severe malformation. In this case, the source of inoculum was a culture of a legume (Vigna unguiculata) which was highly infected by CMV.