How to prevent and cure astragalus powdery mildew?

How to prevent and cure astragalus powdery mildew? Please introduce Astragalus membranaceus as a wild or cultivated species. Astragalus membranaceus is seriously damaged by powdery mildew during the whole growing period, which directly affects the yield and quality. 1. Symptoms: Astragalus powdery mildew is not only harmful to leaves, but also to stamens, pods, stems and other parts. At the initial stage of the disease, leaves and pods produce sparse white powdery mildew layer. In the later stage of the disease, the white powder was gray-white, the leaves were withered and yellow, and many small black spots appeared on the diseased leaves. 2. Pathogen: Astragalus powdery mildew is caused by the infection of powdery mildew in pea. The closed cysts are globose or oblate, dark brown, and there are several vesicles in the closed cysts, which are oval, Obovate, colorless and with short stalks. 3. Occurrence characteristics: according to the investigation, Astragalus powdery mildew formed a sexual generation in late September and overwintered with ascomycetes on the diseased body. When the temperature reached more than 20 degrees in May of the following year, the spores germinated, and the biennial astragalus plants were first infected, the disease center appeared, the bacteria multiplied, repeatedly infected, white powdery matter appeared on the leaves, spread through the wind, and quickly spread to the neighboring plants. The disease was very serious from August to September, and the prevalence rate and severity reached 100%. The ascomycetes were formed from late September to early October, and the disease remains fell into the soil for the winter. The occurrence of the disease is characterized by the emergence of the disease center in the field, and then spread in all directions. 6. Prevention and control methods: (1) Agricultural control: burning the fallen leaves of residual plants and reducing the source of overwintering bacteria. According to the habit of Astragalus powdery mildew pathogen overwintering on litter, after harvesting the aboveground part of Astragalus membranaceus, the residual branches and leaves were swept away and burned in order to depress the source of overwintering bacteria. (2) Chemical control: the occurrence period of Astragalus powdery mildew is longer, and the best period is from June to October. Spray 50% topiramate or 50% carbendazim 800 times to 1000 times at the initial stage of the disease, once every 10 days, 2 to 3 times in a row. Spraying once in the middle and later stage, using 25% trimethoprim WP4000 double liquid spray, the control effect is more than 90%. In addition, 70%WP, 70% mancozeb WP500-800 double liquid spray can be used for prevention and control. Click to get more planting techniques of Radix Astragali