First, the harvest of virus-free seed potatoes The virus-free seed potatoes should be timely harvested, generally in late October, the average daily temperature of about 15 °C harvest is appropriate. If the harvest period is too late, the virus-free seed potato is frozen in the field, and its resistance to disease is poor, and it is perishable during the early storage period. Should choose sunny weather, in the morning plan to harvest seed potato drying, entering the pit in the afternoon of the same day; if the day can not enter the pit, must be covered overnight to prevent freezing of seed potatoes. When harvesting, light planing, light loading, light transport, and light unloading should be done to minimize seed potato damage. When entering the pit, strict quality control should be implemented to remove the seed potatoes with damage, pests and diseases, cracks, and weights less than 100 g and that do not meet the characteristics of the species. Second, the preparation of storage pits choose to shelter from the sun, high dry terrain, solid soil, low groundwater level, convenient transportation management, drainage conditions in a good place to build cellar. If it is stored in an old cellar, it must be completely cleaned and disinfected. The method of disinfection is: scrape the top layer of topsoil in the pit and then use quicklime, formalin, carbendazim, or sulfur fumigation. Before planting potatoes into the pit, they must be covered with a layer of corn stalks on the ground and around, which not only reduces the damage of seed potatoes but also absorbs excess moisture. III. Management of Seed Potato Pits Seedlings are stored for 1 to 20 days after entering the pit. As the temperature is relatively high during this period, the seed potato respiration is strong, the moisture discharged is large, the humidity is high, and the pit temperature is easy to rise. Attention should be paid to opening windows and doors in time. And vents to cool and loose. When the cellar temperature drops to 13 to 15°C, immediately close the doors and windows, adjust the vents, and prevent the cellar temperature from dropping sharply. From the 20th day after the seedlings enter the pit to the middle of the second year of the second year, it is the middle period of storage. During this period, the temperature is low and the seed potatoes are vulnerable to freezing. Therefore, in addition to closing doors and windows and ventilation holes, it is necessary to add cold cotton curtains outside the doors and windows or The seed potatoes are covered with moisturizing grasshoppers, so that the temperature in the pits is kept between 11 and 13°C. After mid-February, it is the late period of storage. During this period, temperature and ground temperature rise rapidly, but often there are more cold currents and unstable temperatures. After a long-term storage, the physiological function of seed potato is poor, and it is particularly sensitive to low temperatures. Therefore, the stability of the cellar temperature should be the main factor in the later period, so that the cellar temperature can be maintained within the range of 13 to 14°C. In short, the storage temperature of seed potato can not be lower than 9 °C, the seed potatoes are vulnerable to freezing damage; can not be higher than 15 °C, high seed germination, and prone to soft rot of sweet potatoes, reduce the pit of the seed potatoes rate. The cellar humidity is maintained between 75% and 85%. During the storage period, if a diseased potato is found, the pit shall be cleaned out in time, and some powdery fungicide or quicklime shall be sprinkled on the bad rotten potato to prevent the disease from spreading; if the rotten potato is more, the potato stack can be removed and rotted. Potato, remember not to fall down pit. China Agricultural Network Editor