What is onion purple spot? How to prevent and cure?

What is onion purple spot? How to prevent? Please guide onion purple spot disease: first, symptoms purple spot disease mainly harm onions, onions, but also infected harm garlic, leek. It mainly damages leaves, pedicels and bulbs on onion. Lesions begin at leaf tips or at wounds damaged by thrips. The initial lesions are small, gray to pale brown, purplish in the center, and black-gray mold. The lesion quickly expanded into an oval or spindle shape, concave, dark purple, forming concentric rings surrounded by yellow halos. When the humidity is high, the disease spots expand to the whole leaves, often making the onion leaves turn yellow and die or break from bottom to top, seriously affecting the yield and quality of fresh onion. II. Prevention and control methods 1. Clean the countryside and remove infectious sources such as sick bodies. 2. Strengthen management, apply more base fertilizer, topdressing, onion growth robust, enhance disease resistance. After the disease to control irrigation to reduce soil moisture, early control thrips, so as not to cause wounds. 3. Chemical control: seed soaking with 40% formaldehyde 300 times solution for 3 hours, soaked in time after washing. At the early stage of disease, spray 75% chlorothalonil WP 600 times solution, 64% anti-virus alum WP 500 times solution, 80% chlorothalonil mancozeb 500 times solution, 40% Dafu Dan 500 times solution, 50% prohydantoin 1500 times solution, 2% multi-antibiotic 30ppm, 50% Sukeling 30- 50g, onion garlic bacteria net and other chemicals spray. Any one of the above agents can be selected, and all kinds of agents should be used alternately, once every 7-10 days, for 3 consecutive times. Add 5-10 grams of neutral washing powder per 10 kilograms of liquid medicine to increase the adhesiveness of the liquid medicine. Click for more onion growing techniques Click for more vegetable growing techniques