Causes of Potato Degeneration and How to Prevent It

(1) Causes of Potato Degeneration

When potatoes are planted in spring in the hot summer regions of the south, after one or several years the yield gradually declines, and there may even be no harvest at all; this phenomenon is called potato degeneration. The direct external cause of potato degeneration is damage by viruses. Common ones in the south include mosaic virus, leafroll virus, common mosaic virus and spindle tuber viroid. These viruses are transmitted through mechanical friction, aphids, leafhoppers or soil nematodes and other vectors, infecting the plants and causing degeneration. High temperature is the indirect external cause of potato degeneration. When potatoes are cultivated under high temperatures, their growth vigor weakens and their disease tolerance declines. Moreover, high temperatures favor virus reproduction, infection and spread within the plant, thereby aggravating the harm from viruses and worsening degeneration.

The internal cause of potato degeneration is the variety's antiviral capacity. Varieties with strong disease resistance show milder symptoms and less severe degeneration, while varieties with weak disease resistance show severe symptoms and more serious degeneration. Therefore, varieties with strong disease resistance should be selected.

(2) Measures to Prevent Potato Degeneration

1. Select varieties with strong disease resistance. Selecting varieties with strong disease resistance is an effective measure to prevent degeneration. At the same time, attention should be paid to improving the seed potato breeding system and regulations, establishing seed-producing bases in high mountains, and combining the selection of good varieties with virus prevention and seed preservation, so as to maintain the productivity of good varieties and extend their years of use.

2. Autumn planting and late planting for seed production. With autumn planting and late planting for seed production, the tuber-forming period occurs under cool climate conditions, the plants grow robustly, disease resistance is enhanced, and virus reproduction and infection are unfavorable, so degeneration can be reduced.

3. Eliminate viruses: (1) Select superior plants for expanded propagation. In fields where virus infection is not yet serious, select robust and superior individual plants for propagation and seed production, and eliminate diseased plants. (2) Use seedling tubers as seed. Potato viruses rarely invade pollen, eggs and seed embryos; therefore, through sexual reproduction the viruses accumulated in the asexual generations can be eliminated, producing virus-free seeds, seedlings and seedling tubers, and preventing degeneration. (3) Virus-free seed potatoes through shoot-tip culture. The shoot-tip meristem basically does not carry viruses; therefore, virus-free plants and tubers can be obtained through shoot-tip tissue culture, and these virus-free foundation seed tubers can then be used as seed in production, which can eliminate most viruses and prevent degeneration. (4) Improve cultivation techniques and storage conditions. Adopting suitable cultivation measures such as planting in sandy loam, high fertilizer and water, rational close planting, strengthening field management, controlling aphids and timely early harvesting can all promote robust plant growth, enhance the ability to resist degeneration, reduce viruses in the field and prevent degeneration. During storage, avoid tubers being affected by high temperatures or damaged by low-temperature freezing, as well as water loss and shriveling, premature sprouting, nutrient loss and damage from diseases and pests, so as to prevent seed potatoes from aging, losing viability and undergoing degeneration.