Why does cotton have rotten roots?

Cotton may have anthracnose, symptoms: cottonseed can be damaged after germination and rot in the soil. The injured light, can also be unearthed, the seedling stem base produced purplish red stripes, and then expanded into a fusiform disease spot, slightly sunken, serious water loss vertical crack, and finally withered the seedlings. The masses call it rotting root disease. The disease spots on the cotyledons are mostly on the edge of the leaves, semicircular, round in the leaves, grayish brown, and reddish brown on the outside. The disease spot on the bell begins to be very small, red-purple, and then expands and becomes black and sunken. When it is wet and overcast, the disease spot produces reddish-brown sticky material, which is the spore of the pathogen, called conidia. Diseased bells often rot or form stiff flaps. Leaves, stems and flowers are also occasionally infected. Disease regularity: the pathogen lives in the remaining stems, leaves and rotten bolls in seeds and cotton fields, invades the seedlings after sowing, produces conidia, and then spreads infection. When cotton bolls were damaged in the later stage, the pathogen could invade the inside of the seed. After sowing, the disease of low temperature overcast and rainy seedlings was serious, and it was rainy before flower harvest, and the boll disease increased. Prevention and control methods: (1) strengthen the prevention and control measures of agriculture, improve the quality of sowing, and level the land before sowing. It is required to sow seeds at the right time, and the sowing depth is 3.5 to 5cm, so as to avoid being too deep and too shallow. Appropriate early seedling, timely pest control, diligent ploughing, deep ploughing, combined with the application of fast-acting fertilizer, reduce soil moisture, increase soil temperature and cultivate strong seedlings. (2) select cottonseeds and dry them more than half a month before sowing. In the northern cotton area, soak the seeds in 55-60 ℃ warm soup for 30 minutes, turn them 2-3 times during soaking, and then soak the seeds at room temperature until they absorb enough water. (3) Cotton seeds were treated with chemicals. Seed dressing with pentachloronitrobenzene, rice foot green and mixed seed ling + thiram can treat both blight and red rot, or seed dressing with pentachloronitrobenzene + carbendazim, pentachloronitrobenzene + thiram (or anthrax) can treat both blight and red rot.