1. Choose a field with high and dry terrain, and cultivate with deep furrows and high ridges, so that no water will accumulate after the rain stops.

2, the use of organic fertilizer should be fully decomposed, and shall not be mixed with crop residues;

3. The nutrient soil for seedling raising in paddy-upland rotation should be sterile soil, which should be dried for more than three weeks before use;

4. Selecting disease-resistant coated seeds, and sterilizing with seed dressing agent or seed soaking agent if the seeds are not coated;

5. It is an important measure to prevent and control diseases and insect pests by using medicinal soil as covering soil after sowing and spraying pesticides once before transplanting;

6, reasonable close planting, timely removal of diseased leaves, diseased plants, and take them out of the field for burning, and apply drugs or quicklime to the diseased points;

Preventive and therapeutic drugs

Seed dressing agent

50% copper succinate wettable powder with 0.4% of seed weight for seed dressing.

Nongkang 75 1 sterilizer 100 times solution 15 ml mixed with 200 g seeds, sucked dry and dried in the shade.

pressurized spray

50% Sukeling WP 1000 times solution

4000 times solution of 72% agricultural streptomycin wettable powder

Neophytomycin 4000 times solution

Symptom compilation

This disease mainly harms leaves. When the seedlings are damaged, the cotyledons initially produce waterlogging spots, and then quickly die or spread to the true leaves, and the root pulp turns black and gradually withers. Adult infection leads to leaf spot disease as black vein. Most of the lesions spread inward from the leaf margin, forming a "V"-shaped brown-yellow leaf spot. The surrounding tissue of the spot is pale yellow, and there is no obvious boundary with the healthy part. In severe cases, large yellow-brown spots or reticular black veins are formed. V-shaped lesion is the key feature of black rot recognition. Petiole infection, along the vascular bundle upward expansion, leading to dry rot or bending off. When the weather is dry, the lesion is dry or perforation is formed.

Occurrence law

Pathogens can overwinter in seeds or diseased soil and invade from water holes or wounds; Seeds can carry bacteria, and bacteria can live on seeds for about 28 months, which is one of the main ways of long-distance transmission of diseases. Most of them begin to get sick from rosette stage to ball stage; Germs spread through rain, irrigation water and farm tools, and can spread for a long distance by using seeds and seedlings with germs. High temperature, high humidity and rainy weather, dew condensation on leaves and water spitting at the edge of leaves are all conducive to the onset; Low-lying, poor drainage, frequent floods, early planting, perennial continuous cropping of cruciferous vegetables; Applying immature organic fertilizer and nitrogen fertilizer, the growth is poor or prosperous, the root system is damaged during intertillage, and the plots with more pests and heavier diseases are also seriously ill; Especially after heavy rain, diseases are very popular.