What medicine is used to prevent and cure potato late blight?

What are the hazards of potato late blight? What medicine is used to prevent and cure potato late blight? Also ask experienced netizens to help introduce that potato late blight is the main disease in potato planting area, which occurs seriously in winter. The disease harms leaves, petioles, stems and tubers, resulting in great losses in production. Therefore, the farming network has sorted out the harm and control methods of potato late blight, which are listed below for netizens' reference. The harm of potato late blight: the potato with late blight initially showed small dark green disease spots at the leaf tip and edge of the leaves. Under humid conditions, the disease spots expanded rapidly and showed waterlogged irregular dark green disease spots. The edge of the diseased leaf curled up and withered, and the downy mildew layer formed by the pathogen could be seen on the edge of the disease spot on the back of the leaf. When the potato late blight disease is serious, the disease spot extends to the veins, petioles and stems, and the diseased leaves die and fall off. The infected tubers initially showed small brown spots and later expanded into sunken dark brown irregular spots. A layer of brown dry tissue can be seen after the diseased potato is cut. The pathogen of potato late blight mainly overwintered in the tuber and invaded the stems and leaves with the growth of buds after sowing. The pathogen further spread and infected through air and water flow. Rainy, foggy and dewy weather is suitable for the disease. It is most popular when the temperature is about 20 ℃ and the humidity is high. Prevention and control methods of potato late blight: first, strictly select the seed potato before sowing, remove the rotten potato, and select the healthy and disease-free seed potato. Concentrated producing areas, it is necessary to establish a disease-free seed potato base to provide disease-free and healthy seed potatoes for farmers. Method 2. Disinfect the seed potato. After spreading out the seed potato, the seed potato can be sprayed evenly with 5 grams of 58% metalaxyl manganese zinc wettable powder and 2.5 kg of water, and the seeds can be sown after drying. Third, reasonable close planting of potatoes, in low-lying, more Rain Water planting areas, timely drainage can reduce the spread of bacteria. Methods fourth, timely removal of diseased potato leaves for chemical control. In the early stage of the disease, the diseased leaves in the center of the disease were removed, and metalaxyl manganese zinc or broad-spectrum fungicide carbendazim was used for 1-3 times. Methods 5. The epidemic of late blight is strong, and the prevention and control strategy should be based on early prevention and control, and if there are conditions for the occurrence of the disease, spraying prevention should be done in advance. Choose 25% metalaxyl wettable powder 500 times, or 58% metalaxyl manganese zinc wettable powder 500 times, or 40% aluminum triethyl phosphate 300 times, or 70% mancozeb wettable powder 800 times, or 50% carbendazim wettable powder 500 times, or 50% carbendazim wettable powder 500 times, or 64% germicidal alum 500 times Or 60% ethyl phosphine aluminum wettable powder 500x liquid, or 72% Kelou wettable powder 70000x liquid, or 69% A ·mn-Zn wettable powder 1000 times liquid, or 72.2% chloramphenicol water agent 800x liquid, or 1 ∶ 1 ∶ 200x Bordeaux solution. Spray the medicine once every 7 to 10 days and spray for 2 to 3 times. In order to slow down the emergence of drug resistance, attention should be paid to the rotation of drugs. Potato slicing method what is virus-free potato