Timely control of black rot of cruciferous vegetables

The black rot disease of cruciferous vegetables in Beijing Jiaojia Daily mainly occurs in broccoli, cabbage flowers, Chinese cabbage, radish, mustard, and indigo, and the incidence has gradually increased in recent years, reducing the yield and quality of vegetables. Seriously affect the income of vegetable farmers. Daxing District Plant Protection Station recently conducted a general survey of broccoli and cabbage flowers and pests, and found that the incidence of black rot was over 85% and the diseased plant rate was 15% to 50%. The rainfall in the city this autumn is more than normal, which is conducive to the occurrence and prevalence of black rot. It is hoped that the farmers can prevent and treat it in time.

Symptoms: The black rot disease of cruciferous vegetables is caused by bacterial infection. It is an epidemic disease. The typical symptoms are manifested in causing vascular necrosis and darkening, but it does not rot or stink. Seedlings, plants can be disease. The incidence of seedling emergence before emergence can not be unearthed, seedlings unearthed cotyledons after the incidence of water-like shape, gradually withered or spread to the true leaves, so that the true leaf veins appear black spots or thin black spots. The incidence of adult plants mostly starts from the margins where the leaf margins and pests are harmed, and "V"-shaped yellow brown spots appear. The leaf tissue around the lesion is light yellow, and the boundary between the normal leaf tissue is not obvious, and sometimes the bacteria can develop inward along the veins to form a yellow vein. The leaves of cruciferous vegetables infected the disease. The bacteria expanded upwards along the vascular bundles, appearing pale brown, causing some of the vegetable rots to dry and rot, causing the leaves to sway to one side, sometimes resulting in delamination and shedding. The disease and the soft rot disease are complicated by the expansion of the disease, causing the stem and stem base to rot. In severe cases, the plants are wilting and dumping. The onset of the strain showed only leaf shedding, darkening of the pith moss, and finally withered. The external symptoms of radish infection are often not obvious, but after the incision, the vascular bundle becomes black, and the serious internal tissues dry rot and become hollow.

Second, the route of transmission and disease conditions: The initial infection source of the disease is seed or seed strains, soil residues. The bacteria can survive winter in seeds and undecomposed diseases, and can survive for 2 to 3 years, spreading through wind and rain, irrigation water, agricultural operations, and insect activities. Seed transport will also cause diseases to spread far away. The invasive route begins mainly with leaf margins and wounds that are pest-infested. After intrusion, it expands upward and downward, causing systemic infection. In infected strains, germs can enter the seed pods or seed coats from the vascular bundles or umbilicals of the stems to carry the seeds. The growth temperature of this bacteria is 25～30°C, and it is resistant to dryness, high temperature and rain or dew, and fog, which is conducive to the invasion of pathogens. Low-lying, poorly-drained plots occur. In particular, early sowing, cruciferous continuous cropping, planting too dense, extensive management, plant leggy, insect pests occurred in serious field weight.

Third, prevention and control methods:

1. Select disease-resistant varieties and collect seeds from disease-free or disease-free plants.

2. 2 to 3 years of rotation with non-cruciferous vegetables to reduce the source of field bacteria.

3. Seed disinfection. Seed soaked with cold water, and then soaked in warm water at 50 °C soak for 20 minutes, remove and re-germination after soaking with cold water; can also be soaked with 200-fold solution of 50% Daisen ammonium solution for 15 to 20 minutes, then rinse with water Dry sowing.

4. Sorghum cultivation, timely sowing, not too early. Reasonably water, suitable for seedlings. After the rain, ditch drainage in time to prevent the accumulation of water in the field. Rational fertilization promotes robust growth of plants and improves plant disease resistance.

5. Timely removal of diseased plants, removal of diseased leaves, reducing the chance of repeated infections in field bacteria. After the harvest, clean the garden and bring the sick body to the field to be buried or burned. Deeply turning the soil to accelerate the decay of the diseased body and reduce the re-infestation of the bacteria source.

6. Chemical control. In the initial stage of disease, spray 72% of agricultural streptomycin sulfate soluble powder 3000～4000 times solution in time, or 1 million units of neomycin solution powder 3000～4000 times solution, or 20% bronchobacillus (Thiococcus copper) suspension agent 500～600 Dilution, or 77% can kill WP 400 to 500 times. Spray once every 7 to 10 days, and spray 2 or 3 times.