The nutritional value of alfalfa is very high, and the economic value is naturally high. Therefore, the yield of planting alfalfa is also very good, but in the process of growth of alfalfa, pests and diseases can not be avoided. Powdery mildew is a common disease. Let's let Let's take a look at the symptoms and prevention methods of powdery mildew. Symptoms of powdery mildew Also known as eucalyptus leaf spot. Mainly harmful to leaves and fruits. The leaf is infected with a round to nearly round lesion, the size is 2-4mm, the edge of the lesion is brown, the center is grayish white, and the back of the leaf is often black gray mold. Fruit sickness also produces similar symptoms. Pathways and pathogenesis of chalky mildew The pathogens are overwintered by mycelium or conidia in the dead leaves of the cockroaches or in the soil with the diseased fruit. The conidia of the next year are spread by the wind and rain for initial infection and reinfection, and the damage is expanded. High temperature and rainy years, high soil moisture, humid air, soil deficiency, and plant weakness are prone to disease. Prevention and treatment of chalky mildew (1) Select good varieties. Such as Ning Hao No. 1. Clean the garden in the fall after the fall leaves, remove the diseased leaves and diseased fruit, concentrate deep burial or burn to reduce the source of bacteria. (2) Strengthen cultivation management, advocate the application of compost made by Japanese enzyme bacteria, increase the application of phosphorus and potassium fertilizer, and enhance disease resistance. (3) Beginning in June, spraying 70% mancozeb WP 500 times solution or 75% chlorothalonil WP 600 times solution, 64% antivirus WP WP 500 times solution, 30% green suspension suspension 400 times liquid, once every 10 days or so, continuous control 2-3 times. The drug was stopped 7 days before harvesting. More pesticide knowledge, please pay attention to pesticide network Lincoln Welding Torch And Accessories Lincoin Type welding torch EDAWELD COMPANY LIMITED , https://www.jsedaweld.com