Occurrence and Control of Black Rot in Cabbage
Black rot is one of the major diseases of cabbage vegetables. In the early stage, leaf spots and black veins can be caused, which directly affect the normal photosynthesis of the plants. In the later period, the plants can cause wilting or dead, which seriously affects the yield and quality of the vegetables, resulting in reduced production and income. I. Pathogens and Symptoms The pathogen of black rot of Brassica oleracea is pathogenic type of Xanthomonas campestris ssp. oleracea, which belongs to the genus Bacteria. Cabbage vegetables such as cabbage, amaranth, and kale are all pathogenic, and mainly damage the leaves, leaves or leaves. The emergence of seedlings before emergence of seedlings is not emerged. After emergence, the infected cotyledons are immersed in water, the root pith is darkened, and the seedlings are withered. True leaf disease, pathogens can invade from the leaf margin, appear "V" shaped brown lesions. Invasive from the wound, irregular brown spots can appear on any part of the leaf, and the spots are light yellow. The bacteria can develop along the veins and petioles and spread to the stems and roots, causing the vascular bundles in the stems and roots to darken, causing the plants to wilt until they die. The bulbs are cut open and the vascular bundles are all blackened or rotted, but not stinky. Under dry conditions, the bulbs are black-hearted or dry rot, distinct from soft rot. Second, the incidence of pathogenic conditions in the seed or sick body overwintering. Sick seeds are sowed that the germs invade from the leaf margins of the seedlings' cotyledons or true leaves. Sometimes the seedlings are unable to emerge due to seedling infestation, and they sometimes die shortly after excavation. It is also an important primary source of infestation that pathogens remain in the field along with the disease. When the leaves of adult plants are infested, the pathogens can invade from the water holes or wounds of the leaf margins. The pathogens quickly enter the vascular bundle and expand with the top and bottom, resulting in systemic infection. In the retained strains, the germs can enter the seed pods from the vascular bundles of the fruit pods to cause bacteria on the surface of the seeds, or invade the seeding bacterium from the umbilicus. The optimum temperature for the growth of pathogenic bacteria is 25-30°C, with high temperatures and heavy rain, serious pests and continuous cropping. Third, the prevention and treatment methods 1, and non-characterized vegetables for more than 2-3 years of rotation. 2, from the disease-free strains seed or seed disinfection before sowing, can be soaked in warm water at 50 °C for 20 minutes, and then in the water cooling, drying after sowing; or 1.5% of the seed weight bleaching powder, add a small amount of water, the seeds mix After soaking, put it in a container for 16 hours after sealing. 3, to strengthen the cultivation and management and pest control. Timely sowing, appropriate seedlings, pay attention to the prevention and control of underground pests. As soon as possible tillage soil, in order to accelerate the decomposition of diseased plants, reduce the number of bacteria. Level land, sorghum cultivation is conducive to irrigation and drainage, good ventilation and light, is conducive to wound healing. Pay attention to the prevention and control of Plutella xylostella, cabbage caterpillar, yellow song strips and other pests. 4, chemical control. At the beginning of the disease, spray 72% of agricultural streptomycin sulfate soluble powder 4000 times or 50% carbendazim wettable powder 1000 times, 58% ledomemi manganese zinc soluble powder 500-800 times, when severe disease may occur every 7 - Spray once every 10 days.