Diseased tissue, exposed by cutting, is brown, grey or black and dry to slightly moist and cheesy. Cavities are often formed within the tuber. There may be white or pink mold near the edges of decay areas, and the mold growth is often seen on the surface of tubers in storage. The amount of decay in storage depends upon the amouht of fungus in the soil, the amount of mechanical damage done to the tubers during digging and harvesting, and on the susceptibility of the potato variety. Fusarium and Verticillium Wilts Wilt diseases caused by Fusarium spp. and Verticillium spp.
Plants infected with wilts start to show symptoms in the middle of the growing season.
Individual leaves first turn pale green or yellow, leaves on affected stems then wilt, and finally the entire plant dies prematurely. The lower stems of diseased plants and tubers have brown discoloration in the vascular tissue when cut open. Both Fusarium spp. The disease can become established through the use of infected seed. Viral Diseases Potato Leaf Roll Potato leaf roll is the most important viral disease of potatoes in Alberta.