The author visited the countryside and found that some greenhouses had yellowing near the growing point of cucumber vines, and some of the top leaves had yellowing and whitening between the veins, and some showed yellow spots or plaques. The main reason is the lack of zinc and iron, root injury, drug injury, hormonal poisoning or disease. Here, the author reminds the vegetable farmers to distinguish the causes and treat them symptomatically.
Zinc and iron lack zinc and iron as trace elements and are often neglected by vegetable farmers. Over time, when cucumbers excessively absorb zinc and iron in the soil, and vegetable growers do not pay attention to supplements, zinc and iron deficiency in the soil may be easily caused. Yellow head." The first is the yellowing of the parietal lobe, the veins are still green, yellow and white in the veins between the posterior veins, and the leaf margin is gradually necrotic and dry. In this regard, it is recommended that farmers in the base fertilizer should pay attention to the use of micro-fertilizers, such as ferric sulfate per acre about 2 kg, zinc sulfate 1-2 kg. After the symptoms appear, spraying foliar fertilizer containing zinc and iron in time can relieve this symptom.
Roots were injured with root injuries, and those who were light caused "yellow heads". In severe cases, cucumber plants wilted and died. The main cause of root injury is high or low ground temperature, excessive water and fertilizer. When the leaves are rooted in roots, the ability to absorb nutrients after a root injury is significantly reduced, then the "yellowhead" is prone to occur. It is recommended that vegetable growers should reduce the amount of watering after root injury, use small water, replenish nutrient fertilizer to protect root vines, humic acid fertilizer or Apollo 963 chitin fertilizer, so that cucumber roots can be restored as soon as possible. Normal growth, so that the leaves turn green.
After occurrence of phytotoxicity, phytotoxicity of cucumbers occurs first on the leaves, the leaves are dry or yellow, and the leaves are chlorotic, malformed, and there are spots or plaques. It is recommended that the pesticide should be dispensed strictly in accordance with the prescribed concentration when spraying. Do not mix multiple pesticides as much as possible. After phytotoxicity occurs, cytokinin and nucleotide-based foliar fertilizers can be sprayed in time for remission.
Excessive melons cause hormonal poisoning, resulting in yellowing and stiffening of the parietal lobe. After hormonal intoxication, the top sheet is stiff and the leaf margin curls up and grows slowly or not long. For the plants with hormonal intoxication, the sprayed cloud 120 or cloud-enhanced tree fruit plus nucleotide foliar fertilizer can relieve the symptoms under the precondition of suspending the pods.
Infectious diseases such as severe brown spot disease in recent years, when the harm is serious, the yellow leaves of the top leaves of the cucumber are connected to pieces, resulting in cucumber "yellow head." In this regard, thiophanate-methyl or carbendazim plus Baitai or acetaminophen can be used for prevention and treatment.
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