Control methods of Black Rot of Cabbage

When the main symptoms occur in the adult stage, most of the disease spots develop inward from the leaf margin, showing a "v" shape, which is a yellowish brown withered spot. The leaf tissue around the disease spot is yellowish, and the boundary between the disease spot and the healthy part is not obvious. sometimes the pathogen can develop inward along the leaf vein, forming a reticular yellow vein. The cause of the disease is the primary infection source of the disease is the residual body in the seed or soil. The bacteria can survive for 2-3 years and spread through irrigation water, agricultural operations and wounds caused by pests. The suitable temperature for the growth of this strain is 25 ℃-30 ℃, the lowest is 5 ℃ and the highest is 39 ℃. The disease is serious in the fields which are resistant to dryness, generally high temperature, early sowing, extensive management and untimely pest control. Control methods (1) seed disinfection: soak seeds in 55 ℃ warm water for 15 minutes, then immediately move to cold water to cool down, take out and dry and sow seeds; soak seeds with 50% Dysen zinc 200 times solution for 20 minutes, wash and dry and sow seeds; or soak seeds with streptomycin 1000 times solution or chlortetracycline 1000 times solution for 2 hours. (2) strengthening cultivation management, not sowing too early, watering reasonably, squatting seedlings at the right time, paying attention to reducing wounds, and cleaning up the countryside in time after harvest. (3) Pharmaceutical prevention and treatment: 100m / L streptomycin or agricultural streptomycin or chloramphenicol 50Mel 100mg / L can be sprayed at the initial stage of the disease.