Cucumber downy mildew people commonly known as "running horse" and "black hair", is one of the major diseases in the production of cucumber in summer. It has become fierce, spreads quickly, and has caused serious damage. In almost a week or two, nearly entire leaves of cucumbers have died, seriously affecting yield, causing serious economic losses to vegetable growers, and must be highly valued. Symptoms The onset began with the lower leaves, followed by many water-stained, pale green spots along the edges of the leaves, and quickly developed into yellow-green to yellow lesions that were limited by the veins and the lesions were polygonal. When the water film was formed in the morning or on the leaf surface, the outer tissues of the lesion showed dark green water stains. In humid conditions, the diseased leaves develop a purple-brown or dark brown irregular spot on the back, and the surface is covered with downy mildew. In severe cases, the lesions fuse with each other, the leaves turn dark brown, the edges curl up, and the leaves die from the bottom up. The law of incidence The disease is an airborne fungal disease caused by the infestation of Pseudoperonospora of Cuba. As long as the temperature is between 16-20°C and the relative humidity is above 85%, the disease can occur. The optimal temperature is 20-26°C. Foliar condensation or water film is a necessary condition for downy mildew infection. During the infection, spores produced by sporangia, germinated tube, or sporangia directly sprouted into the tube, and were directly invaded by the leaf epidermis, causing disease epidemics. Climate or cold or hot, humid air, large temperature difference between day and night, will cause the occurrence and prevalence of downy mildew. Control methods 1. Agricultural control. Selection of disease-resistant varieties, such as Jin He No. 1, No. 2, No. 3, No. 4, Xia Feng No. 1, No. 2 Amaranth, Zhongnong 1101, etc. Strengthen the cultivation and management centered on water control, pouring ground water, and paying attention to ventilation and humidity. Applying basic fertilizer and adding phosphorus and potassium fertilizers will help enhance the disease resistance of plants. Reasonably arrange the planting density, remove the old leaves and diseased leaves in time, make the fields ventilation and light, reduce the moisture in the field, and reduce the occurrence and spread of diseases. The cucumbers in the greenhouse can adopt high-temperature stuffy shed method, and close the greenhouse at noon for 2 hours, so that the temperature of the upper part of the plant can reach 44-46°C, which can kill the downy mildew in the shed, once every 7 days. 2. Chemical control. To be preventive, spray prevention should begin when downy mildew does not occur. When the disease occurs, it is necessary to spray and control immediately. The commonly used pharmaceuticals are: 58% metalaxyl MnZn WP 500 times, 64% WP WP 500 times, 72.2% Proccel 800 times, 80% Triethylaluminum Phosphate (Ethyl Phosphorus Aluminate, Insecthuramol) 600x Solution, 70% ADP Aluminum Manganese Zinc Wettable Powder 500x, 72% Cream Urea Manganese Zinc Wettable Powder 700x, DuPont Kelu 800 The fluid is sprayed once every 7-8 days and the number of sprays is determined depending on the condition. In order to avoid drug resistance, the above pesticides should be used alternately in order to improve the control effect. Angiography Kit,angiography system,angiography machine,angiography surgical grown Anesthesia Medical Co., Ltd. , https://www.honestymed.com