Sunburn damage

• On the foliage

Under the direct action of the sun (and sometimes in the presence of dew, which has a magnifying glass effect), the green tissues start to dehydrate and turn black. Necrosis of the tissues is complete after a few hours. It affects the leaflets or parts of the leaf blade. Some cultivars are more susceptible than others.

• On the tubers

Tubers exposed to the sun and high temperatures for several hours, in the field or later, suffer from “sunburn” and take on a metallic appearance with browning of the underlying tissues (“golden blotch” or sunscald). The surface tissues dry out (photo 1) and the tubers are unsuitable for storage.