Common onion diseases include downy mildew, purple spot, gray mold and anthrax. Prevention and control adopt the plant protection policy of “prevention-oriented, comprehensive prevention and controlâ€. Based on the comprehensive prevention and control of agriculture, use high-efficiency, low-toxicity, low-residue pesticides for prevention and control. 1. Select disease-resistant varieties that are suitable for local growth, implement crop rotation, increase organic fertilizer, phosphate fertilizer, potash fertilizer, and micro-fertilizer, deep-deepen the soil for more than 40 days, improve the soil, try to eliminate and reduce residual pathogens in the soil, and reduce the source of infection. 2. Strengthen the management of fertilizers and water, timely spray “Tianda-2116†and other plant growth regulators to improve the disease resistance and adaptability of plants. 3. Scientific selection of pesticides. Downy mildew, with 70% metalaxyl Mn-Zn 500x, 72% DuPont Kelu 600-800x, 72.2% Prec 700x, green copper 800x, Trik 800x Liquid, Cryo-Cyanide 600 times, 75% Chlorothalonil 800 times, or 80% Ethylphosphine Aluminum 500 times liquid +64% antivirus 500 times liquid spray control. Purple spot, in the early stages of disease, use 78% Cobo WP 500 times, 41.5% fluoxetine 1500 times, 75% chlorothalonil WP 600 times, 64% WP WP or 50% iprodione (Phoenone) WP 1000 times spray control. Botrytis cinerea, at the beginning of the disease, was sprayed with 25% Prochloraz EC 1000x, SFJ 1200x SC, Veloxon 3000x or 50% Propionin WP 1500x. Anthracnose, at the beginning of the disease, is sprayed with 10% Shigao water dispersible granules 1500-2000 times, 25% prochloraz EC 1000 times or 50% anthraquinone Fumei WP 500-800 times. Melatonin Capsules,Melatonin Soft Capsule,Rhodiola Capsules,Folic Acid Powder Xi'an complex bio-tech CO.,LTD. , https://www.complexpowder.com