Bruises on potatoes: is it enough to cut them away?. Black spots are usually caused by physiological disorders, pressure points in storage in spring and impacts.
The Bavarian State Agricultural Institute recommends to only store dry potatoes, to prevent bruising and to store the potatoes “dark, well ventilated, at approx. 5-8 °C and high humidity”. Unpleasantly smelling, wet and already infected tubers should be “removed immediately’.