Bacterial keratoses and downy mildews are two kinds of diseases that often occur in cucumber production. Because bacterial keratoses are very similar to the early symptoms of downy mildew, it is difficult to distinguish them. The differences and prevention measures between the two are introduced as follows:
Bacterial keratoses differ significantly from downy mildew lesions
Both the lesion size and the disease are caused by the limitation of the veins to form a polygonal lesion, the shape is more difficult to distinguish, but the lesion size is more easily distinguishable, the bacterial spot lesions are smaller, and the downy mildew lesions are larger. Diffusion spread quickly, easy to connect into large lesions.
Lesion color Bacterial keratoses lesions are lighter in color, pale yellowish brown or off-white; downy mildew lesions are dark in color and appear yellow-brown.
The lesions are perforated in the later stage of the bacterial keratoses and the perforation is often found in the late stage of the downy mildew lesions.
On the back, when the air is wet, the bacterial leaf spot on the back of the diseased leaf is overflowing with white pus. On the back of the downy mildew leaf, a villous purple-gray to purple-black mold layer grows on the back.
Bacterial keratoses at the site of onset may develop on leaves, stems, and fruits. The onset of stems and petioles often produces water-stained, yellow lesions, often with white mucous; the initial onset of the disease is water-stained and brownish depressions develop. Spots, cracks, secrete white mucus, lesions can be inward, discoloration. Downy mildew mainly damages the leaves.
Induced causes of low temperature and high humidity can easily induce bacterial angular spot; normal temperature and high humidity can easily induce fungal downy mildew.
Chemical control varies
Bacterial keratoses should be applied at the early stage of the disease. It can be sprayed with 5% citric acid copper powder. Ningnanmycin, streptomycin for agriculture, kasugamycin, copper hydroxide, ceric chloride, and B can also be used. Phosphine aluminum, aluminum, copper acetate and other 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.
In the early stage of disease, downy mildew or chlorothalonil and sulfur, procymidone, cymoxanil, and metalaxyl are used as the compound smoke agent. They are placed in 4 to 5 places in the shed, with cigarettes or cigarettes. They ignited when the fire ignited, closed the shed when the cigarettes were smoked, closed and fumigated overnight, and were ventilated 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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