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What are the control methods for cotton red leaf disease?

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Cotton red leaf disease is a physiological disorder that has a relatively large impact on cotton yield and quality. This disease usually begins to occur at the early flowering stage. If control is not timely, by the full flowering stage to the boll-setting stage the affected area expands and the condition worsens. When the disease first appears, the leaves take on a dark green color, then gradually thicken and wrinkle, becoming brittle, with yellow spots appearing between the veins while the veins remain green. As the disease worsens, the leaf edges begin to curl downward and turn from yellow to purplish red, withering and dropping off, until the cotton plant is left as bare stalks and dies. The main causes of cotton red leaf disease

Cotton red leaf disease is a physiological disorder that has a relatively large impact on cotton yield and quality. This disease usually begins to occur at the early flowering stage. If control is not timely, by the full flowering stage to the boll-setting stage the affected area expands and the condition worsens. When the disease first appears, the leaves take on a dark green color, then gradually thicken and wrinkle, becoming brittle, with yellow spots appearing between the veins while the veins remain green. As the disease worsens, the leaf edges begin to curl downward and turn from yellow to purplish red, withering and dropping off, until the cotton plant is left as bare stalks and dies.

The main causes of cotton red leaf disease: one is poor, infertile land, with compacted cotton fields and poor aeration; another is improper fertilization that damages the roots, affecting the deep penetration of the main root and reducing stress resistance; another is severe root disease at the seedling stage, which weakens the ability to absorb fertilizer and water; the fourth is intercropping of wheat and cotton, where the soil does not get plowed for years, the plow layer is shallow, and the nutritional area for cotton roots is small, all of which easily induce this disease.

Judging from the causes of cotton red leaf disease, to prevent this disease the first thing is rational fertilization: apply sufficient base fertilizer, apply a heavy flower-and-boll fertilizer and a good topping fertilizer, and increase the application of organic fertilizer and potassium fertilizer, achieving a reasonable ratio of nitrogen, phosphorus and potassium. During the cotton growing period, if cotton leaves are found to have turned dark green, or the edges have begun to turn yellow, a mixed solution of 0.2% potassium dihydrogen phosphate and 2% urea can be sprayed on the foliage; for more serious cases, spray twice in succession. When air humidity is high after rain, the disease often worsens, and at this time 0.2% potassium dihydrogen phosphate should also be sprayed on the day it clears up, which can inhibit the occurrence of this disease to a certain extent.

Second, shallow intertillage should be carried out at the right time. Cultivate frequently, and especially during drought carry out timely shallow intertillage to reduce soil moisture evaporation and enhance the stress resistance of the cotton plants. After rain, intertillage should also be carried out promptly to break up soil compaction and improve soil aeration.

In addition, irrigation should be carried out in a timely manner. The bud-and-boll stage is the period of most vigorous cotton growth, with a large water demand, so when high temperature and drought occur, water should be applied immediately. If all these measures are carried out, the occurrence of red leaf disease can be reduced or inhibited.

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