Recently, many vegetable farmers have reported that yellow leaves have appeared on cucumbers, which has seriously affected the yield of cucumbers and even led to the occurrence of outbreaks. There are many reasons for the yellowing of cucumber leaves, which must be dialectical.
First, the wounded yellow leaves
The yellow leaves caused by the root injury are the main reasons for the yellow leaves of the cucumber. The yellow leaves are mainly caused by watering and fertilizing the roots improperly, or they are caused by the roots of the roots caused by the cloudy days after watering. It is recommended that sprinkler irrigation should be used in combination with comprehensive prevention and control. Spraying, that is, foliar spraying with zinc and iron-containing foliar fertilizers to prevent leaf senescence and promote leaf greening. Irrigation, i.e., rooting, seedling growth, or chitin promotes root growth.
Second, the lack of yellow leaves
The lack of yellow leaves is divided into middle and lower old leaves first yellow and middle and upper young leaves first yellow. Middle and lower old yellow leaves, the lack of elements mostly nitrogen, potassium, etc.; middle and upper leaves first yellow, the lack of elements mostly calcium, iron, zinc and so on. Recommendations should be based on the different parts of the yellow leaf disease, different performance, choose the right leaf fertilizer spray supplement. Potassium dihydrogen phosphate 500 times can be sprayed if there is a shortage of potassium, and nitrogen deficiency can be sprayed with 300 times the urea solution.
Third, disease yellow leaves
Diseases such as downy mildew and angular spot disease are important causes of yellow leaves of cucumber. Downy mildew and keratoses mostly damage the middle and lower leaves of cucumber. The main symptoms of downy mildew: When the leaves become infected, water-spotted lesions appear on the leaf margins and on the back of the leaves at the beginning, and then the lesions gradually expand, appearing as triangular yellow-brown or yellow-brown patches, and when the humidity is high, the back or leaf surface of the leaves. The president will grow a gray moldy layer, and when the plant grows serious, it will turn yellow. The main difference between keratoses and downy mildew symptoms is that the lesions of keratoderma are easy to break and perforation, and when the humidity is high, the back of the leaves overflows milky white muddy watery pellicles. For diseased yellow leaves, fungicides should be applied in a timely manner to prevent and control, usually 7 to 10 days to spray once. Downy mildew can be used Kelu, Anke, frost urea manganese zinc and other agents to control; angular spot can be used Garinong, can be killed, thiazolyl and other agents.
Fourth, drug yellow leaves
When farmers use their medicines to prevent diseases, improper use of medicines can also cause yellowing of leaves. The general amount of medication is too large, such as spraying mancozeb excessive manganese prone to manganese poisoning, resulting in yellow leaves, leaf vein distortion and so on. It is recommended to use medications that are reasonable and that once the injury occurs, the foliar spray can be used to provide 600 times more liquid and 600 times more liquid Yunda 120 to ease.
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