Cucumber downy mildew is commonly known as black hair, fire dragon, and horse running. It is one of the most common diseases in cucumber production. It occurs in various cucumber producing areas. The disease is a kind of airborne and epidemic disease. It is a strong force, rapid spread, and serious disease. The whole plant leaves can die in two weeks, generally reducing production by 10% to 30%. The local field can cause plant mortality of more than 50%, or even no harvest. After the disease occurs in cucumber, the leaves are yellow and the melons are small and small. The larvae die in advance or without melons, which seriously affects the yield and quality of cucumber. Incidence conditions: Cucumber downy mildew is a fungal disease. The bacteria overwinter on the leaves, immersed in the mesophyll by means of water droplets on the leaves, and spread by air circulation and field operations. When the temperature is 20-24 ° C, the relative humidity is above 85%, and when there are water drops on the leaves, the disease is prevalent. Main symptoms: Cucumber downy mildew mainly harms the leaves, yellow-green lesions on the front of the diseased leaves, water-soaked spots on the leaf margins and leaf backs, and the lesions are limited by the veins to form a polygonal chloasma. When wet, there are black gray mold on the back of the leaves. In the layer, the diseased leaves are curled to form yellow dry leaves, and are easily broken. Control methods: strengthen field management, prevent high humidity; promote soilless seedlings, or disinfect soil; can be high-canola flower warm shacks in the greenhouse, or spray dust and smoke, etc., such as 45% chlorothalonil smoke treatment 8-10 hours after re-ventilation, you can also spray 5% chlorothalonil dust or 10% anti-mold spirit dust (1 kg per acre); in order to improve the disease resistance of plants, spray 0.1% on the foliage Urea or 0.3% potassium dihydrogen phosphate, plus the same amount of white sugar water; in the early stage of the disease, spray 75% chlorothalonil WP 500 times solution, or spray 400 times solution of anti-virus 矾 wet powder. At the same time, when the cucumber downy mildew is serious, the temperature and suffocation method can be used for prevention and treatment. That is, according to the weather forecast, the weather is selected for more than 2 consecutive days, and the first day of the day, the melon faucet (main vine growing point) is dropped to prevent the baking seedlings, and then a temperature meter is hung in a conspicuous position and a place visible outside the shed, and then Watering; the shed will be sealed for shacking at around 10:00 the next day. Due to the sunlight, the temperature in the shed is 45-46 °C (the temperature can be properly released when the temperature is too high). After 90 minutes of stagnation, the air is gradually cooled down, and the temperature is controlled at 25-28 °C. In this way, it can kill downy mildew and control the effect of melon. After the shed, increase the foliar spray, the effect is better. Lose Weight Plant Extract,Poria Extract,Seaweed Extract,Codonopsis Pilosula Extract Fufeng Sinuote Biotechnology Co.,Ltd. , https://www.sntbiology.com