What are the control methods of cucumber downy mildew?
(1) Jin Yan No.2, No.4, No.6, No.7, Jinza No.65438 +0, Jingbiyu Zhongnong No.65438 +0, Xinong No.58, Yuji No.8, Shanghai Foreign Firm, etc.
(2) Cultivation, disease prevention, temperature control and humidity reduction. In the morning, the temperature in the shed is controlled at 28-32 degrees Celsius, the highest temperature is 35 degrees Celsius and the humidity is 60%-70%. The specific measures are as follows: after sunrise, make full use of the morning light to close the room to raise the temperature. When the temperature in the shed exceeds 28 degrees Celsius, start ventilation. When it exceeds 32 degrees Celsius, increase ventilation in the afternoon to reduce the temperature in the shed to 20-25 degrees Celsius. After the humidity drops to about 60% and enters the night, the temperature should be controlled below 65438 03 degrees Celsius, or the humidity should be reduced to control whether to cool down or dehumidify. According to the seasonal temperature change, irrigation must be carried out in sunny morning, not in cloudy or rainy day. In order to prevent excessive irrigation, the doors and windows in the shed should be closed immediately after irrigation, so that the indoor temperature in the shed can be raised to 32 degrees Celsius for 1 hour, and then the ventilation can be greatly reduced, which can reduce the formation of moisture on the leaves in the evening.
(3) Chemical control ① Fumigation: When the central diseased plant of downy mildew is found, the dosage of 45% chlorothalonil fumigant can be 200-250g per mu of shed or 0.3-0.4g per cubic meter, and the smoke can be smoked after the shed is closed at night. It is better to distribute the efficacy evenly in the shed at 4-5 o'clock in rainy and snowy weather. Light it with dark fire, close the shed after smoking and ventilate it every seven days. The tighter the shed is, the better. ② Spraying: 500-fold solution of 58% toxic manganese and zinc is sprayed at the initial stage, or 500-fold solution of 25% toxic mildew (metalaxyl) is mixed with 65% zineb at the ratio of 1: 2, 200-250-fold solution of 40% ethyl phosphate (metalaxyl) and 600-fold solution of 75% chlorothalonil wettable powder. Pay attention to the alternate use of various agents when spraying 40% synergistic Ruifu 500 times solution. ③ Powder spraying: Powder spraying with 5% chlorothalonil powder is not only low in cost, but also simple in operation, especially in winter, which is beneficial to control the development of diseases. Use 0.75~ 1 kg per mu of greenhouse to spray powder with Fengshou No.5 or 10 duster, once in the morning and once in the evening.
(4) When the disease is fierce and chemical control can't be controlled, high temperature closed shed should be considered. The way to close the greenhouse at high temperature is to close the greenhouse on sunny days, so that the temperature of the growing point of cucumber can quickly rise to 45 degrees Celsius (cucumbers above 48 degrees Celsius are vulnerable, but the effect below 42 degrees Celsius is not obvious, and wheat straw or paraffin can be lit when it is difficult), or after the first closure of the greenhouse, it can be closed again every four days. Once again, during the period of 10~ 15 days, the development of the disease can also be controlled, but attention should be paid to watering the greenhouse. The soil moisture must be kept as high as possible the next day, and water should be poured once the next day to supplement the water consumption. Before closing the greenhouse, bend the faucet and cover it under the big leaves to prevent burns. When the greenhouse is closed, stick thermometers should be hung at the upper, middle and lower parts of the greenhouse, close to the cucumber growth point. Generally speaking, it is 6000000. 5000 1 . 66668666665
(5) Supplementing nutrition, increasing the application of phosphorus and potassium fertilizer, and improving the disease resistance of plants. In the middle and late growth stage, nitrogen and sugar solution were sprayed on the leaves to supplement nutrition, and the proportion of white sugar was 1, urea was 0.5, and water was 100. When downy mildew occurs, add 58% toxic manganese zinc or 65% mancozeb 500-600 times solution and spray it on the leaves at 3-4 pm.