Black rot is one of the most common important diseases of cruciferous vegetables during the summer and autumn rains. It usually occurs in the middle to late September to the middle of October. It is a disease caused by bacteria. The disease can affect cruciferous vegetables such as cabbage, cabbage, mustard and radish, among which cabbage is the most affected.
Disease symptoms
The main damage leaves, but also against leaf or bulb, each growth period can occur. Before the seedlings emerged, they caused bad seeds and caused seedling deficiency. The damage to the cotyledon of seedlings was water-stained, causing the plants to quickly die or spread to the true leaves. The bacteria on the true leaf mainly invade from the leaf margin and form a "V" shaped lesion; it can also invade from the wound in the leaf and form irregular lesions in the vicinity. The lesions are yellow-brown to gray-brown necrotic with a distinct yellow-green or yellow halo, and the diseased health boundary is not obvious. The veins in the lesions are gray-brown or dark brown, and contracted (thicker veins are more pronounced). The pathogen further spreads along the leaf veins in or around the leaf, and may form a large area of ​​necrosis or an irregular yellow to yellow-brown large spot with a pale yellowish edge. Severe disease can cause the whole leaf to die or part or all of the outer leaves to rot. When the climate is dry, the lesions are dry or perforated. The germs further spread through the stem vascular bundles to shorten the stems and leaves, causing the outer leaves to turn yellow until they die. The culprit damaged by bulbs turns black or rot, but it is not stinky. It is different from soft rot of cabbage, but it is often mixed with soft rot. It is a common devastating disease of cabbage and can cause large areas of cabbage to die or even to close.
The germs enter the pods from the vascular bundles of the fruit pods, or invade the seeds from the umbilicus, causing seeds to colonize.
Prevention
1. The bacteria can survive in the field for about one year. Therefore, two years of crop rotation should be carried out between the severe disease fields and non-cruciferous vegetables to reduce the occurrence of diseases.
2. Use disease-free zones to plant seeds or disease-free plants to pick seeds, and use disease-resistant varieties or seeds for disinfection. Soaking before sowing can be warm soup, soaking with hot water at 50 °C for 20 minutes, immediately after cooling with cold water; or soaking seed, with 20% quinacridone 1000 times wettable powder, or 77% can be obtained powder 800-1000 Soaking the seed for 20 minutes, after washing, wash the seeds thoroughly with clean water.
3. Use disease-free soil plugs or nutritious soil blocks to raise seedlings, cultivate disease-free strong seedlings, use mulching mulching to cover planting, and remove sick and weak seedlings before planting. Remove diseased plants and bury them in early stages or after harvest to prevent the spread of pathogens.
4. To strengthen the cultivation and management. Timely sowing, appropriate seedlings, rain-proof seedlings; reasonable close planting, sorghum deep-groove cultivation, timely drainage after rain, dip irrigation when needed, reduce the humidity in the field; apply adequate decomposition of organic fertilizer, so that nitrogen, phosphorus, potassium and reasonable cooperation Application; timely pest control, reduce the chance of wounds and infection; clean the garden, timely removal of sick bodies; implement 2-3 times of cultivating loose soil, promote root development.
5. Chemical control. The beginning of adulthood began spraying. Pharmacy can be made of 47% Chlorhexidine Copper wettable powder 700-800 times, or 58.3% can kill 2000 dry suspension 800 times, or 77% can kill wettable particulate powder 500 times, or 72% of agricultural sulfuric acid Streptomycin soluble powder 4000 times, or 20% thiazole copper suspension 500 times, or 25% thiophene WP 800 times, or 20% quinacridone WP 1000 times, etc. spray. Application interval 10 days or so, continuous prevention and treatment 2-3 times.
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