Prevention and control methods:
1. Selection of disease-resistant varieties: select varieties with strong disease-resistant ability and eliminate tender and juicy white-sensitive varieties in the old ward.
2. Reasonable rotation: rotation should be carried out for more than 2 to 3 years if conditions permit, and continuous cropping or interplanting with cruciferous crops should be avoided as far as possible. Rice, corn, barley, sorghum, onion, garlic and leek are suitable for the previous crops of Chinese cabbage.
3. High border cultivation: It is better to choose sandy loam with deep soil layer and loose fertility. Before transplanting 15~20 days, dig the soil deeply, and then raise the ridge, about 35 cm high, so as to drain water and prevent waterlogging; Increase soil aeration and improve plant disease resistance.
4. Sowing at the right time: sowing too late and the temperature in the growing period is too low, which is easy to cause looseness or no package in the later stage and affect the yield; Seeding too early, because the temperature is too high, the seedlings grow slowly, which is easy to cause pests and diseases and reduce the quality. Generally, it is advisable to sow and raise seedlings before and after beginning of autumn.
5. Strengthen fertilizer and water management: apply sufficient decomposed human and animal manure and compost base fertilizer. Topdressing should be light first and then concentrated, and the dosage should be gradually increased. The use of undecomposed human feces is strictly prohibited. After entering the core filling period, we should pay attention to frequent irrigation, and each irrigation should not be too much, and it should be drained with irrigation. After the rain, it is necessary to clear the ditch and drain the water, so that the rain stops and the fields dry up.
6. Eliminate diseased plants: strengthen field inspection, uproot diseased plants in time, and sprinkle quicklime in the root holes of diseased plants for disinfection.
7. Chemical control: 200-300 units of agricultural streptomycin, 200-400 units of chloramphenicol, 500-600 times of antibacterial agent "401"and 500- 1000 times of dixone powder can be sprayed before or at the initial stage of onset.