1, disease symptoms During the expansion of the bulbs, translucent grey spots appeared on the lower part of the outer leaves of the first and second leaves. The base of the leaf sheath was softened and spoiled, causing the outer leaves to fold and the lesions to expand downward. The bulbs became immersed in water at the beginning of the disease, and the interior of the bulbs began to rot, emitting a foul odor. 2. Pathogens The pathogen of soft rot on Yuancong is Carrot soft rot bacteria, which belongs to bacteria. Pathogens and rot in the soil and soil are the main sources of infection in the field, and generally the seeds are not borne by bacteria. The bacteria invade through wounds and spread mainly through fertilizer, rainwater, and irrigation water. In addition to harming onions, the bacteria can also infect cabbage, cabbage, celery, carrots, potatoes and so on. 3, the cause of the disease 3.1 Climatic element Onion bulb expansion period is generally between June and July. The high temperature during this period is the suitable temperature for the occurrence of soft rot, and the amount of rainfall is a major factor in the prevalence of soft rot. 3.2 The varieties cultivated in recent years are mostly disease-resistant varieties, such as Kamui in Japan, Fast Bear, and Crown King of the United States. 3.3 Rinse mouth arrangement According to the findings of several years of investigation, it was found that the crops that were formerly used as onions, cabbages, cabbages, potatoes, etc., were severely affected by the disease, and the fields used as soybeans, maize, and other field crops were lightly affected. 3.4 Planting methods Low-lying drainage is poor, water in the field, high soil moisture, and poor permeability are conducive to disease occurrence. The survey found that low-lying land was heavier than the high-lying land and the level was heavier than that of ridges and sorghum. 3.5 Wound Causes Germs can invade through wounds. Wounds include natural wounds, insect wounds, mechanical wounds, prolonged rain, excessive watering, etc., which can cause wounds and the onset of disease. Litters such as leaf miners, mantle, and thrips can also cause wounds. These wounds increase the chance of onset. 3.6 Fertilizer partial application of nitrogen fertilizer, the amount of organic fertilizer is less than the weight of the site of balanced fertilization. 4, comprehensive prevention Adopting comprehensive prevention and control measures focusing on prevention and control of agriculture, supplemented by chemical control, and emphasis on prevention. 4.1 Agricultural Prevention and Control 1 Crop rotation: The onion shall work best with food crops, and should not be rotated with onion garlic, cruciferous, umbelliferous vegetables. 2 selection of disease-resistant varieties: such as Japan's Kamui, fast bear, the United States, the Crown King, Daqing yellow. (3) Choose lands that can be filled with dry energy and energy, and adopt sorghum or ridge cultivation methods, and cover the mulch. 4 strengthen management: nurturing strong seedlings, timely sowing, reduce the amount of nitrogen fertilizer applied organic fertilizer, shallow watering, timely weeding. 4.2 Chemical control 1 Control of pests is generally started at the beginning of June. For pests such as onion thrips, leafminers and other pests, they are sprayed with 1500-fold of chrysanthemum emulsifiable concentrate or 1000-fold of 50% phoxim EC. 50% phoxim EC was used to control roots, and 500 times of the phoxim EC and 800 times of the 90% crystal trichlorfon were rooted. 2In the early stage of the onset of soft rot, 77% can be used to kill particles WP 500 times, 72% of agricultural streptomycin 4000 times, neophytin 4000 times, every 7 days and 10 days, even spray 2 ?3 times. Fire Sign,Luminous Safety Sign,Luminescent Safety Sign,Glow In The Dark Super Sign JINAN REALGLOW CO.,LTD , https://www.realglowsign.com