PVY symptoms vary with strain of the virus, cultivar and environmental conditions. PVY symptoms include yellow, light green and dark green “mosaic” patterns on leaves, leaf drop, brown or black (necrotic) line patterns often on veins or shoots, necrotic lesions on leaves and stems, rugosity (wrinkling), yellow flecking, stunted growth, death of growing points, tuber cracking and tuber necrosis. Tuber necrosis caused by PVY is called potato tuber necrotic ringspot disease (PTNRD). Affected tubers show raised rings of darker brown or reddened skin that can progress to sunken necrotic areas. Necrosis beneath the rings may extend into the tuber flesh.
Some emerging strains of PVY can cause tuber necrosis in some cultivars and most emerging strains cause mild foliar symptoms in most cultivars. The photos below illustrate some typical types of symptoms seen on foliage and tubers. More photos can be found on the PVY symptom page with links to photos of symptoms on many different North American cultivars. This comprehensive gallery of symptoms by cultivar can also be found here PVY Photo Gallery.
Diagnosis of PVY with lab tests
A visual diagnosis based on symptoms can be confirmed with lab testing. Information on PVY diagnostic tests of foliar or tuber tissue can be found here Diagnostic Lab Testing.
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