I. Selection of resistant varieties Cucumber varieties with strong ability to resist downy mildew and suitable for growth in greenhouses include Jinchun No. 3 and Changchun Mickey.
Second, ecological control It is to control the temperature and humidity in the shed to create an environmental condition that can prevent the growth and development of the bacteria, but can ensure the normal growth and development of the cucumber, so as to achieve the purpose of disease prevention.
1. According to the requirements of temperature and humidity indicators for ecological control of cucumber downy mildew, manage the temperature and humidity in the greenhouse. The whole day can be roughly divided into 4 stages:
1 After the sunrise, raise the temperature of the shed to 20~30°C as soon as possible. When the temperature exceeds 30°C, the air will be dehumidified. When the relative humidity drops to 60-70%, the temperature will be raised to 30°C to meet the photosynthesis of cucumber. Need, while preventing the infection of the bacteria and controlling the occurrence of the disease;
2 afternoon shed temperature is maintained at 20 ~ 25 ° C, in order to transport and transform organic matter, but this temperature is suitable for the germination and infection of the bacteria, at this time should reduce the humidity to about 60%, single factor control of disease occurrence;
3 Pay attention to heat preservation after sunset to prevent the shed temperature from falling too fast and the humidity to increase sharply. The temperature before the night is kept at 15-20 °C, the humidity is lower than 85%, and the disease is controlled by the single factor of humidity. If the humidity exceeds 85%, the temperature should be reduced to 13 ~ 15 ° C, and temperature control disease occurs;
4 After midnight to sunrise, the humidity in the shed rises with the temperature drop. When the humidity exceeds 90%, the shed temperature of 10 °C ~ 13 °C is used to control the disease, and the respiratory consumption of the cucumber plant can be reduced. The water leaf is kept on the leaf surface of the cucumber by releasing air and draining moisture. The time of the water droplets. The daily average minimum temperature is above 13 °C, which can be vented all night.
2. Reasonable watering is an important measure to control the humidity in the shed. The general requirement is to water the water on sunny days, not on cloudy days; watering in the morning, not pouring in the afternoon; dark water pouring (dark irrigation under the membrane), the water is not poured. Immediately after watering, the greenhouse will be warmed up, and when the temperature of the shed reaches 30 °C, it will be ventilated.
3. When downy mildew occurs, you can choose to perform a high temperature shack on a sunny day. The day before the suffocating shed must be watered first, and the next day at noon, the shed temperature is raised to 45 ° C for 2 hours to kill pathogens on the plant and soil surface. Then slowly release the wind, and then close the shed when the temperature of the shed drops to 25 °C. 10 days high temperature suffocating shed once, 2 to 3 times in a row.
Third, chemical control 1, spray powder Generally use 5% bactericidal powder, spray 1000 grams per acre. Use the Harvest 5 type duster to evenly spray the powder, and do not spray against the plant. Depending on the condition, spray once every 8 to 10 days, and spray 4 to 5 times. Sunny days must be carried out in the morning or in the evening, and sprayed throughout the day in rainy and rainy days.
2. Smoked When the central diseased plant appeared, it was immediately smoked with 20% chlorothalonil-curing complex aerosol, 250 grams per acre. After closing the shed in the evening, put the tablets evenly in the shed, close the shed after the smoke, and ventilate the next morning. Smoke once every 7 days, depending on the condition, smoke 4 to 5 times.
3. Spraying Many agents for controlling cucumber downy mildew. Can be used interchangeably to improve effectiveness. 25% syphilis 800 times solution, 40% ethyl phosphorus aluminum 250 times solution can be used. 72% DuPont Klu 600 times liquid and 72% Plex 600 times liquid spray, spray once every 5 to 7 days, even spray 2 to 3 times.
Winter warm greenhouse cucumber downy mildew
Cucumber downy mildew is fast, prone to prevalence, and is a serious hazard. It is the first damage to the production of yellow claws in greenhouses. According to the test and practice in the past two years, on the basis of the selection of resistant varieties, the prevention and control of cucumber downy mildew, with the focus on ecological control, supplemented by chemical protection, can effectively control its occurrence and harm.
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