Why Are My Potatoes Wilting?

Potato Growth

• Potatoes have several phases during growth. The first is vegetative where the eyes produce sprouts that soon develop leaves. Then roots form that produce a mat in the top 18 to 24 inches of soil. Next, tubers initiate and begin to bulk up. Finally the plant is putting all its energy into tuber formation and the leafy vegetation dies back. The yellowing and wilting of the visible plant is a cue that it is time to start harvesting the tubers.

Verticillium Wilt

• Verticillium wilt is a common potato disease and is very contagious. Certified seed potatoes may still carry the pathogen and it persists in soils, even over winter. The symptoms appear after a dry period or when the plant is heavily laden with crop. The bottom leaves begin to yellow and get V-shaped lesions on the terminal ends. Leaves dry out and fall off. The infected plant usually survives, but it will appear stunted and production will suffer.

Fusarium Wilt

• There are several species of Fusarium fungus, which cause the wilt. Signs of the disease first appear in mid-to-late season, with the worst symptoms in hot, dry weather. The first sign is wilting, which may occur on only one side of the potato plant. Then the leaves fade and turn yellow. Eventually the leaves get a bronze color and dry out. The disease works its way up from the base of the plant and contorts the stems, preventing them from forming normally. Inside the stem is a dark chocolate brown color. The plant will die from this disease.

Water Management

• Potato plants need plenty of water during active tuber production or they will wilt. They need soil moisture levels of 60 percent to 80 percent and are quite sensitive to moisture stress. Initially the plants need 0.02 inches of water per day, which increases to 0.25 inches by the time the leafy plants are grown and spreading. The only time the requirements are lessened is at the end of the season when tuber formation is mostly finished.