A Detailed Guide to Common Potato Diseases and Their Control Methods

Potato is an important crop in China with extremely wide uses. However, it is also prone to a relatively large number of diseases, and since its tubers grow underground, some of them are quite difficult to detect. Below, Qinnong Web introduces several common diseases so that everyone can gain some understanding of this area.

1. Late blight

Late blight in potatoes mostly occurs on the leaves, and over time spreads to the tubers, with fairly obvious symptoms. In the early stage of the disease, spots begin to appear on the leaves and slowly turn brown; in dry conditions the whole plant gradually dries up and wilts, while in moist environments it starts to rot and give off a foul smell, and eventually the tubers become the same. It can be controlled with a 50% copper metalaxyl dilution of 700—800 times, once a week for one month.

2. Powdery scab

Powdery scab in potatoes mostly affects the roots and tubers. On affected potatoes, dark brown spots appear on the surface, which eventually rupture to form uneven little pits. When the disease occurs, inspecting the roots of the plant reveals some swollen little lumps, which eventually split open into pitted lesions. It mostly occurs concentrated in the rainy season. It can be controlled by spraying with a 1500-times dilution of 50% carbendazim wettable powder, or before sowing by soaking in a 2% hydrochloric acid solution for 3-5 minutes, then drying before sowing.

3. Dry rot

Dry rot has an extremely large impact on potato tubers, and its occurrence is mostly concentrated on the tubers. It shows as sunken brown spots appearing on the surface of the potato tubers, which then slowly corrode inward, accompanied by white mold-like growth; in the end the entire interior of the tuber becomes a black, dried-out substance, and in the most severe cases the whole tuber takes on a dry-rotted state. At the early stage of planting, a 58% metalaxyl-mancozeb wettable powder can be used for control.

4. Soft rot

This is a disease that appears in many plants, and a major cause is soil that is too moist; so the appearance of this disease means that the soil in this area has excessive moisture. Its biggest characteristic is that it gives off a foul odor. When the disease occurs, it starts from the most moist part of the leaves, then spreads to the whole plant; the symptom is rotting, while the unaffected parts turn yellow. It can be controlled with a 500-times dilution of 50% baijuntong wettable powder; in severe cases it is best to remove the plants promptly to avoid spreading.

Potatoes of course have many other diseases as well; here we have only listed a few of the more common ones. Everyone should pay attention to these diseases, and should not only carry out control in the areas where they occur, but also inspect other areas. This can better ensure the yield.