Causes and Control Methods of Potato Green Skin Disorder

[Disease Diagnosis] It mainly occurs on tubers in the late growth stage or during storage. In the field, after some tubers arch out of the soil surface and are exposed to sunlight, the surface tissue turns from yellow to green. The area of greening varies depending on the size of the exposed area. The green tissue can extend into the interior of the tuber and is often accompanied by purple pigment deposition. During storage, when tubers are exposed to natural light, the surface also turns green, sometimes even affecting deep tissues. Usually this greening will not recover by returning the tubers to dark storage.

[Cause] This disease is a physiological disorder. Its direct triggering cause is sunlight exposure. After tubers are exposed to sunlight in the field or after harvest for a period of time, the white bodies in the tissue transform into chlorophyll, causing the tuber tissue to turn green. Some potato varieties tend to set tubers close to the soil surface, or the potato vines have thin hilling, or soil water erosion and drying form cracks, or tuber expansion arches the soil and exposes them, all of which may expose tubers to sunlight in the later stage and lead to sunburn greening. When edible potatoes are displayed in the market, exposure to natural light or fluorescent light will cause the tuber surface, and sometimes even deep tissues, to turn green. In the field, when growing plants receive too little hilling and improper management causes tubers to be exposed in the later stage, green skin is prone to occur. Different potato varieties differ in the severity and depth of development of green skin, and some varieties that tend to set tubers close to the soil surface have a higher incidence of green skin disorder. During storage, the disease develops more slowly under cool conditions than under warm conditions. Once green-skinned potatoes occur, even if the tubers are put back into darkness for long-term storage, the green color cannot fade. Rinsing tubers with a surfactant can reduce the severity of green skin.

[Control Measures] (1) Strengthen field management, do a good job of hilling plants in the late growth stage, and promptly cover exposed tubers, which can effectively reduce green skin. (2) Choose varieties whose tubers are not easily exposed above the soil for planting. (3) During tuber storage, avoid light as much as possible and keep the environment dark. At the same time, maintain a cool temperature as much as possible to slow the rate of green skin development. (4) When conditions permit, rinse tubers with a surfactant to reduce the severity of green skin.