During the growth process of Cucumber planting, due to improper management of planters, causing malnutrition of cucumber, or encountering bad weather and infectious diseases and insect pests, it will cause yellowing of cucumber leaves, which is very unfavorable for cucumber growth, and will lead to serious Cucumber is not harvested. Therefore, today Xiaobian talks about the causes and prevention measures of cucumber yellow leaves, I hope to help everyone.
The yellowing of cucumber leaves is mainly divided into yellow leaf, yellow leaf of downy mildew and yellow leaf of blight. The wording of the control is as follows:
First, the lack of yellow leaves
1, showing symptoms
(1) The yellow leaf of the deficiency type is divided into the middle yellow and the middle yellow, and the middle and upper leaves are yellow.
(2) The middle and lower parts of the old yellow leaves cause elements such as nitrogen, potassium, magnesium and zinc to be difficult to be used by plants.
(3) Nitrogen deficiency: The growth of cucumber plants will be limited, and the older leaves will be green first.
(4) Magnesium deficiency: The chlorosis between the cucumber veins turns yellow, the leaf margin is green or green spots remain, and it is not curled.
(5) Potassium deficiency: leaf margin is chlorotic and even necrotic, and there is chlorosis to necrotic spots on the leaves.
(6) There is no obvious inhibition on the growth of zinc-deficient plants, and the whole leaves have chlorosis to necrotic spots or streaks.
(7) Calcium deficiency: The growth point is dead, the leaves are green and shrink to necrosis, the root system is poorly developed, and the melon is less.
(8) Desulfurization: The growth point is not dead, the leaves are light green, and the stems are small.
(9) Iron deficiency: the growth point is not dead, the leaves are yellow and white.
2, prevention and control measures
(1) Nitrogen deficiency: Foliar application of 0.5 to 1% urea solution 2 to 3 times.
(2) Magnesium deficiency: Foliar application of 1 to 2% magnesium sulfate solution.
(3) Potassium deficiency: Foliar application of 0.3 to 0.5% potassium dihydrogen phosphate solution 2 to 3 times.
(4) Zinc deficiency: Foliar application of 0.2% zinc sulfate solution.
(5) Calcium deficiency: Foliar application of 0.3% calcium chloride solution was performed twice a week.
(6) Sulfur deficiency: Foliar application of 1% potassium sulfate solution.
(7) Iron deficiency: Foliar application of 0.5% ferric sulfate solution.
Second, downy mildew yellow leaves
1, showing symptoms
In the early stage of the disease, the leaves appear as water-stained yellow small round spots on the back of the leaves, and then develop into yellow-brown polygonal lesions. In a high-humidity environment, the back of the lesion grows with a gray-brown mold layer. In severe cases, the lesions are curled and withered.
2, prevention and control measures
Foliar spray control was carried out with toxic mycelium manganese zinc 58% WP (wettable powder, the same below) 500 times solution, or 75% chlorothalonil WP, 50% lysozyme WP600 times solution.
Third, Fusarium, yellow leaf
1, showing symptoms
(1) At the beginning of the disease, some of the leaves are wilting at noon, and return to normal in the morning and evening. If the corresponding prevention and control measures are not taken in time, they will not be restored after repeated days.
(2) The leaf color gradually changed from yellow-green to yellow-brown, and the main vine on the ground surface was brown water-stained and rotted, and gradually dried up, eventually causing the whole plant to die.
2, prevention and control measures
Irrigation with 50% carbendazim WP500 times solution or methyl thiophanate 50% WP500 times solution.
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