Fig. 4.

Potato plants showing viral symptoms in field condition (A) Desiree; PVX infected (mild mosaic and mottling, greening and vein thickening) (B) Cardinal; PLRV infected (severe upward leaf curling, rugosity) (C) Desiree; PVX and PVS mix infection symptoms (severe leaf thickening, yellowing, mosaic and leaf crinkling) (D) Desiree; plant infected with PVX, PVY and PVS (severe leaf thickening, leaf yellowing and severe upward curling, necrotic lesions, sunken veins and mosaic) (E) Desiree; plant symptoms inoculated with PVX and PVS in glasshouse (Leaf thickening, necrotic lesions, mottling and leaf curling) (F) Desiree; Control healthy plants in glasshouse.