What medicine is effective for controlling cotton red leaf disease?

Control the top and promote the bottom to enhance the stress resistance of cotton plants. First, for cotton with vigorous growth, apply the plant growth retardant succinic acid or mepiquat chloride to control excessive growth; use 2-3 grams of mepiquat chloride or 8-12 milliliters of mepiquat chloride per mu, mixed with 50 kg of water for spraying. Second, for cotton fields with compacted soil, cultivate and aerate in time to enhance permeability. Third, for cotton fields in low-lying areas, pay attention to clearing ditches and beds at any time to promote cotton roots to grow downward. Fourth, for cotton fields using plastic film mulching cultivation, remove the plastic film immediately so that cotton roots develop deeper.

Apply more potassium fertilizer to improve fertilization efficiency. For the two types of cotton fields with potential potassium deficiency in the soil or low potassium application, apply 10-15 kg of potassium fertilizer per mu. First, it can meet the cotton's need for potassium fertilizer; second, it can adjust the fertilizer ratio structure in the cotton field and improve the utilization rate of nitrogen fertilizer and phosphate fertilizer.

Foliar spraying to improve the oxygen supply and nutrient absorption environment of the root system. For cotton that has already developed red leaf stem blight, as long as the cotton leaves have not wilted and the main stem growth point is still viable, foliar topdressing can be used to quickly restore reproductive function. First, use 100 milliliters of humic acid active liquid fertilizer Nongshibao per mu, mixed with 45 kg of water for spraying; second, choose a 0.2% potassium dihydrogen phosphate solution and mix it with a fungicide for controlling leaf spot disease, such as Maoling, for spraying.