Downy mildew is an important disease in cucumber production in greenhouses, especially in spring greenhouses. Its onset is characterized by aggressiveness, rapid spread, and severe disease. The entire leaf is allowed to die within two weeks, which seriously threatens cucumber production. Therefore, it is extremely important to control the occurrence and harm of cucumber downy mildew in advance. The following specific measures should be taken:
First, supplement nutrition
Phosphorus and potassium fertilizers should be added before planting, and nutritional supplements should be given according to the growth of cucumbers during the growing period of cucumbers. Spraying potassium dihydrogen phosphate, borax, urea mixed solution, spraying once every 10 days, even spraying 2-3 times, can quickly and effectively provide the required nutrients to plants, promote robust growth of cucumber, improve disease resistance.
Second, ecological control
The conditions for the occurrence of cucumber downy mildew are: temperature 16°C-22°C, relative humidity more than 85%, plant leaves have small water droplets or water film. Therefore, prevention measures are: 1 temperature control. The greenhouse temperature rose to 32°C-35°C as soon as possible to increase photosynthesis. The nighttime temperature is controlled below 16°C in the middle of the night and 13°C in the middle of the night. When the minimum ambient temperature reaches 13°C, it can be ventilated overnight. 2 control wet. Under the premise of ensuring the normal temperature for plant growth, ventilation should be as far as possible so that the condensation time at night does not exceed 2 hours, and the release of wind is mainly to release the top wind. Watering should be carried out on a sunny morning. Immediately after pouring, the temperature should be raised to 32°C in a closed booth. After 1 hour of continuous ventilation, loosen the air. When the temperature drops to 25°C, close the air outlet to increase the temperature. This is repeated 2-3 times. The area of ​​the water film formed by the leaves at night.
Third, high temperature stuffy shed
In the shed, local disease is heavy, but this method is used when the fleas are more robust. Select the sunny morning, first close the doors and windows of the greenhouse, so that the temperature near the cucumber growth point in the greenhouse rises to 45 °C, maintain for 2 hours, and then let the wind cool. The treatment requires high humidity inside the shed and can be poured once a day the previous day.
Dust application
The use of powder dusting has a better control effect. The method is to close the doors and windows, and spray 10% chlorothalonil dust agent with powder sprayer, and the dosage per kilogram is 1 kilogram, which can also cure gray mold and anthrax. Usually sprayed once every 7 days, sprayed 2-3 times.
五ã€Pharmaceutical spray
Select pesticides with low toxicity, low residue, and high efficiency. Downy mildew can be used to prevent and control poisonous sputum, grew, ank, frost urea manganese zinc and other agents spray. Before spraying, we can remove the diseased leaves, especially the old leaves of the lower part, and pay attention to the back of the spray blade. The finer the fog droplets are, the better the effect is. The spraying liquid per acre should not be less than 30 kg.
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