At present, the sweet potato in the north has entered the harvest period and storage period. The common diseases and storage methods of sweet potato are introduced below. Sweet potato is also called sweet potato, sweet potato, sweet potato, sweet potato, sweet potato, sweet potato, etc. The main edible part is the underground hypertrophy tuber. Sweet potatoes can be used as both food and vegetables. In my country, they are mostly used as food crops, while in foreign countries, they are often used as vegetables.

1. Freezing damage

Freezing damage is one of the main reasons for sweet potato rot during storage. Within a week of freezing, the potato pieces are indistinguishable from healthy potatoes. The skin of the potato is slightly dark in color and loses its luster. It feels elastic when pressed lightly with your fingers. When you cut the frozen potato, you can see that the flesh near the skin turns brown rapidly, and the more it is frozen, the more Severely browns faster. The frozen part is water-soaked and used for extrusion, with clear water seeping out. Frozen potato pieces tend to form a hard core, crust, and bitterness. The rot caused by freezing damage generally starts from the surface of the potato pile. If sweet potato is stored for a long time in a low temperature environment below 9 ℃, it will destroy the physiological function of potato pieces and cause freezing damage. After being frozen, it takes a while before it begins to rot. Generally, at 4~5°C, the frost damage lasts for half a month and begins to rot; at 6~7°C, it starts to rot after a month. The longer the low temperature lasts, the more severe the frost damage. There are two situations in which sweet potatoes suffer from freezing damage: one is that the harvest is too late, and the outside of the cellar is frozen, and it begins to rot around 15 days after entering the cellar, which is called freezing damage outside the cellar; the other is in the middle and later stages of storage, due to shallow cellars or poor cold and warm conditions. Freeze damage causes rot. After the potato pieces are frozen, they are easily infected by weak parasitic bacteria and cause rot. Therefore, the physiological freezing damage of sweet potato during storage is closely related to infectious diseases.

Second, the key points of sweet potato storage technology

(1) Warehouse disinfection

The warehouse for storage should be cleaned and disinfected carefully, usually with fumigant disinfectant, with 5-15 g/M 2 distribution of multiple points of combustion, airtight fumigation for 24 hours, and then fully ventilated.

(2) Timely harvest

Sweet potatoes are susceptible to cold damage and must be harvested in time. The temperature for timely harvesting should be 12-15 ℃, not lower than 10 ℃. On the day of harvest, after drying, it should be packed in a basket (box) for storage, and cannot be left overnight to prevent cold damage due to low temperature at night. It can't be exposed to rain either. Sweet potatoes that are damaged and exposed to rain are easy to rot.

(3) Featured potato nuggets

The sweet potatoes used for long-term storage should be strictly selected, and the potato pieces that are damaged by damage, frost, blisters, and pests should be removed. .

(4) Pre-injury treatment

Before storing sweet potatoes, an important pretreatment - callus is required. Because sweet potatoes are thin and brittle when harvested, they are prone to peeling and breakage damage, which is unavoidable during harvesting and handling. Callus is very important for sweet potato storage, especially for those sweet potatoes that are cold at harvest or for a short time after harvest. Called sweet potatoes have increased resistance to black spot and soft rot.

The specific method of callus treatment is to treat for 4 to 6 days at a temperature of 30 to 35 ° C and a humidity of 90 to 95 percent immediately after harvesting, with a water loss rate of 2 to 6 percent. The damaged surface protection structure was restored. If the temperature and humidity during the callus are higher or lower than the above conditions, the callus will progress slowly or not at all. Callus treatment should be carried out immediately after sweet potato harvesting, and the shorter the interval between harvesting and treatment, the better. During the callus period, it is also necessary to ensure adequate ventilation to prevent the accumulation of CO2 or lack of O2, or the generation of condensed water. The callus should be carried out in the storage room or cellar. Once the callus is completed, it should be changed to the normal storage temperature and humidity conditions, and will not be moved in the future to prevent new wounds.

(5) Strengthen management

Management should be strengthened during sweet potato storage.

In the early stage of storage, sweet potatoes breathe vigorously. If the storage temperature and humidity are high during this period, it is easy to make the potato pieces germinate or become diseased. Therefore, it should be turned on for ventilation, cooling and dehumidification. In the mid-storage period, the external temperature is very low, and sweet potatoes are susceptible to cold damage. During this period, the temperature should be kept properly (maintain the temperature above 12 °C) to avoid low temperature damage. In the later stage of storage, the external weather will warm up, the temperature will gradually rise, and the respiration of sweet potatoes will be enhanced. At this time, ventilation should be strengthened in the warehouse to prevent the accumulation of carbon dioxide released by respiration and cause "stuffy cellar" rotten potatoes.

3. Storage method

cold storage

The selected sweet potatoes are put into baskets and then put into the warehouse for stacking. The stored sweet potatoes are pre-injured first. After pre-injury, they quickly enter the warehouse with a storage temperature of 12-15 ℃, that is, they enter the normal management stage. Note that when pre-injury, sprinkle water to humidify, the humidity should reach 90-95%, and during normal management, it should be ventilated and dehumidified, and the humidity should be kept at 85-90%. The storage period is 5 to 7 months. If diseased potatoes are found during storage, they should be picked out immediately to prevent the spread.