What are the symptoms and treatment methods of Chinese cabbage soft rot?

Chinese cabbage soft rot, also called rot disease, rotten head, rotten gourd, rotten gourd head disease, water rot disease, and leaf-drop disease, is a major disease in Chinese cabbage production, mainly affecting leaves, tender and juicy tissues, and stems or roots. The early-stage symptoms and late-stage symptoms are completely different. This disease not only causes damage in the late growth stage of Chinese cabbage, but can also continue to spread and cause damage during storage, resulting in rotten storage cellars. So what are the symptoms of Chinese cabbage soft rot? How is it treated?

1. What are the symptoms of Chinese cabbage soft rot?

1. Base rot type: the plant base rots, the outer leaves wilt and droop to the ground, the head is exposed, and the whole plant falls over at the slightest touch. Farmers in northern China commonly call this “tuo da gua”.

2. Heart rot type: the plant rots from the top downward or from the base upward. Farmers in northern China commonly call this “rotten head” or “rotten gourd”.

3. Leaf scorch type: the leaf margins of the outer leaves scorch and wither, and the diseased leaves rapidly lose water and dry up, appearing like thin paper. Farmers in northern China commonly call this “burnt edges”.

Under dry conditions, the three types of symptoms above cause the rotten diseased leaves to gradually lose water and dry out in the sun, appearing like thin paper and clinging tightly to the head. The diseased and rotten areas all produce a foul hydrogen sulfide odor, which becomes an important feature of this disease and distinguishes it from black rot. Seed-bearing plants of stored Chinese cabbage that carry the bacteria also develop the disease after transplanting, causing the seed plants to wither and die prematurely.

2. How is Chinese cabbage soft rot treated?

1. Choose disease-resistant varieties

Generally, green-stem types are less affected than white-stem types, and late-maturing varieties are more disease-resistant than early-maturing varieties. Open-hearted, upright-cylinder Chinese cabbage has upright outer leaves in the field and good ventilation, so it is less affected than round-head types, but during storage the opposite is true: when round-head varieties are stacked during storage, there are gaps between them that favor ventilation, so they are less affected than upright-cylinder types. Disease-resistant green-stem varieties include Liaobai No. 21, Beijing New No. 3, Jingqiu 80, Jinqiu No. 1, Longbai No. 6, and others.

2. Pay attention to cultivation conditions

In principle, do not practice continuous cropping or neighboring cropping with crops such as cabbage, tomato, and potato, so as to reduce the chance of disease occurrence.

After the previous crop is harvested, plow the field and sun-dry the soil as early as possible to promote the decomposition of diseased residues; choose ridge cultivation for Chinese cabbage, as high-bed cultivation is less affected than flat-bed cultivation.

Appropriately increase the application of decomposed farmyard manure and phosphorus and potassium fertilizers in the base fertilizer to promote vigorous growth of Chinese cabbage and improve its ability to resist pathogen infection; sow late at the appropriate time so that the head-forming stage of Chinese cabbage avoids the hot and rainy season, reducing disease occurrence.

Plant at a reasonable density, thin and finalize seedlings in time, remove old leaves, yellow leaves, and diseased leaves, and increase field ventilation; promptly pull out and deeply bury diseased plants, dig up and expose the soil of diseased planting holes to the sun, and reduce sources of disease.

3. Control insect pests in time and control disease spread

In the early stage, attention should be paid to controlling underground pests. Starting from the larval stage, insects should be inspected frequently. When pests such as striped flea beetles, aphids, cabbage caterpillars, and diamondback moths are found causing damage, pesticides should be sprayed immediately for control.

4. Chemical control

Diseased plants should be pulled out immediately, and a medicinal solution should be poured on the diseased plants and the healthy plants around them to prevent the disease from spreading. In the early stage of disease occurrence, spray once every 7-10 days, alternating and rotating chemicals, and spray 2-3 times continuously depending on the condition of the disease.

Optional chemicals include copper hydroxide, cuprous oxide, thiodiazole-copper, copper-ammonia complex, copper abietate, zineb, streptomycin, Kasugamycin-copper, and others.