Large temperature difference between day and night can easily lead to a decline in disease resistance of cucumbers. Bacterial keratosis is prone to occur and it should be promptly controlled. Cucumber bacterial keratoses occur in a wide range. The leaves, fruits and cranberries of cucumbers can be affected. The leaves are dry and fruit rots in severe cases. The incidence of diseased fields is generally reduced by 10% to 20%, and the severity of illness is up to 40%. , a great threat to the safety of cucumber production. In addition, it should be noted that cucumber bacterial keratoses are very similar to the early symptoms of downy mildew, and should be carefully differentiated and given the right medicine. Cucumber bacterial leaf spot is caused by bacterial infection. Downy mildew is caused by fungal infection and can be distinguished from the following aspects. (1) The size of the lesion. Both diseases are caused by the limitation of the veins to form polygonal lesions. The shape is more difficult to distinguish, but the lesion size is more easily distinguished. The bacterial macular lesions are smaller, while the downy mildew lesions are larger and spread rapidly. , easy to connect into large lesions. (2) lesion color. Bacterial keratosis lesions are lighter in color, appear pale yellowish brown or grayish white; lesions of downy mildew are dark in color and appear yellow-brown. (3) lesion perforation. Bacterial keratoses lesions are easily broken and perforated in the late stage; downy mildew lesions are usually dry but not perforated in later stages. (4) Back features. When the air is wet, the bacterial leaf spot on the back of the leaf spot of the diseased plant is covered with white pus. On the back of the leaf of the downy mildew disease, a villous purplish-gray-purple to purplish-black mold layer grows. (5) The site of the disease. Bacterial keratoses can affect the leaves, stems, and fruits. The incidence of stems and petioles often produces water-stained yellow lesions, often with white mucus. The fruit begins to be water-stained and gradually develops brown pitting lesions. Cracking, secretion of white mucus, lesions can be inward, discoloration. Downy mildew mainly damages the leaves. For cucumber bacterial leaf spot and downy mildew, agricultural control can use greenhouses to regulate the temperature and humidity conditions, create an environment conducive to the growth and development of cucumber, is not conducive to bacterial infection, inhibit disease occurrence. The specific approach: After sunrise in the morning, the temperature in the shed is rapidly increased to 25 to 30°C, and the maximum temperature is not to exceed 33°C. The humidity is about 75%. The temperature and humidity are controlled to meet the requirements of cucumber photosynthesis, and the disease resistance and disease incidence are enhanced. After proper ventilation in the afternoon, the temperature in the shed fell to 20-25°C, and the humidity dropped to about 70%. The night temperature is controlled at 12-15 °C. At dawn, the temperature is reduced to a minimum, and when the humidity reaches saturation, the air is released and the humidity in the booth is reduced. Chemical control, cucumber bacterial angular spot disease in the early onset of medication. Can use 5% copper chloride fertilizer copper powder spray, but also can choose to use Ning Nanmycin, agricultural streptomycin, kasugamycin, copper hydroxide, copper copper phosphine aluminum, aluminum aluminum acetate copper spray control. After the disease enters the epidemic period, the dosage should be increased or the number of medications should be increased. Note alternate medication. For the prevention of downy mildew, in the early stage of disease, choose chlorothalonil smoke agent or chlorothalonil and sulfur, procymidone, cymoxanil, metalaxyl as the compound smoke agent, and place them in the shed at 4 to 5 places. Or cigarettes and other dark flames ignite, closed the shed when the smoke, closed fumigation overnight, ventilation the next morning. Smoked once every 7 days, the number of fumigation depending on the development of the disease may be. In addition, if the mixture of cucumber downy mildew and bacterial keratoses occur, you can use Garnett 47% Spring Thunder Copper wettable powder 600 to 800 times liquid, or 4% pyrimidine nucleoside antibacterial water agent (Fangkang 120, 400 times liquid) Plus neomycin (5000 times) spray control.
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