Prevention and treatment of damping-off disease of hollow cabbage

The symptoms showed that the seeds were infected with rotten seeds before they were unearthed, and after they were unearthed, the infected seeds appeared water stains near the soil surface, softened, appeared basal rot, the disease part constricted, rapidly expanded around the stem for a week, the vegetable seedlings lodged, and the whole plant withered quickly, resulting in pieces of dead seedlings. The suitable temperature for the growth of the disease condition was 15 ~ 16 ℃, and the suitable ground temperature for the disease was 10 ℃. The temperature higher than 30 ℃ was inhibited, and the low temperature was disadvantageous to the growth of the host, but the pathogen could still move, especially under the condition of low temperature and high humidity in the seedling stage, which was beneficial to the disease. When the nutrients in the cotyledons of the seedlings are basically used up, there is a susceptible period before the new roots are firmly rooted, when the true leaves are not extracted, carbohydrates can not increase rapidly, the disease resistance is weak, when there are continuous overcast days or cold currents such as rain and snow, the ground temperature is low, the photosynthesis is weak, the respiration of the seedlings is enhanced, the consumption is increased, and the young stem cells are elongated, and the cell wall thinning bacteria take the opportunity to invade. Therefore, the disease mainly occurs before the seedlings grow 1 or 2 leaves. Chemical prevention and treatment: spraying 40% aluminum triethylphosphonate wettable powder 200 times or 70% ethyl phosphorus at the initial stage of the disease? Manganese zinc wettable powder 500 times liquid, 58 metalaxyl? Manganese zinc wettable powder 500 times solution, 64% poison alum wettable powder 500 times solution, 18% metalaxylamine? Manganese and zinc wettable powder 600x liquid, 69% Anke manganese zinc wettable powder 1000 times liquid, 72.2% Pulic water agent 800x liquid, once every 10 days, continuous prevention and treatment for 2 times and 3 times, and spray evenly. Agricultural control: (1) selection of disease-resistant varieties. (2) promote compost made by enzyme bacteria retting and fully mature organic fertilizer. (3) seed rotation, ridge cultivation or high furrow planting in the lower wetland, reasonable close planting to prevent excessive surface humidity and timely drainage after rain.