Prevention Methods for Sweet Potato Cellar Rot and Storage Management Techniques

The biggest problem during sweet potato storage is cellar rot. Once cellar rot occurs, it may at best reduce the quality of the sweet potatoes, and at worst cause all the sweet potatoes in the cellar to rot, resulting in varying degrees of loss. Sweet potato cellar rot is mostly caused by physiological diseases and infectious diseases. Physiological diseases mainly occur when the temperature is not suitable enough. If the cellar temperature remains below 10°C for a long time, chilling injury is likely to occur and cause cellar rot. If the cellar temperature remains above 20°C for a long time, it favors infection by weak parasitic fungi and the spread of black spot disease, thereby causing cellar rot. Infectious diseases can be divided into two categories: one is diseases that have already occurred in the field and continue to spread during storage, such as black spot disease and stem residue disease; the other is diseases that occur after storage, such as soft rot and blue mold. 

The following technical measures should be taken to prevent sweet potato cellar rot:

1. Build the cellar carefully. The sweet potato cellar should be built in a sheltered, sunny place with firm, dry soil. The sweet potato cellar is required to retain moisture, be well ventilated, be convenient to inspect and manage, and not be prone to collapse. Old cellars should be sprayed with 1.5% formalin solution for disinfection before use. The cellar should be built early before harvesting the sweet potatoes.

2. Harvest at the right time. To avoid freezing injury and chilling injury, harvest on a sunny day before light frost. Cut the vines the same day, dig the sweet potatoes the same day, dry them the same day, and put them into the cellar the same day. During harvesting, they need to be handled and loaded gently to reduce wounds on the tubers.

3. Select before storage. Carefully select before putting them into the cellar, and thoroughly remove diseased, damaged, and moldy-rotten sweet potatoes. The storage amount should preferably account for 2/3 of the cellar capacity. A large cellar with few sweet potatoes will not keep warm, while a small cellar with many sweet potatoes will have high temperature and high humidity, making soft rot likely to occur.

4. Temperature regulation management. In the early stage after putting them into the cellar, keep the cellar temperature at about 20°C and pay attention to ventilation and air permeability. After one week, maintain the cellar temperature at 12°C-15°C, which is the most suitable temperature during the sweet potato storage period. As the air temperature drops, close the cellar opening at the proper time and add coverings so that the minimum temperature at the cellar surface is not lower than 10°C. Set a small hole on top of the cellar, insert a thermometer, and observe the cellar temperature at any time. In early spring, as the air temperature rises, promptly reduce the coverings and gradually enlarge the ventilation pipe to avoid the cellar temperature being too high or too low.