Necrotic strains of Potato virus Y cause the development of necrotic arcs or rings on the surface of tubers. The necrosis extends into the tuber flesh.

Sliced tuber showing necrotic rings on surface and in the tuber flesh. Credit: Philip B. Hamm
Necrotic strains of Potato virus Y cause the development of necrotic arcs or rings on the surface of tubers. The necrosis extends into the tuber flesh. Credit: Philip B. Hamm