How to control the red leaf disease of cotton?

Cotton red leaf disease is a physiological disease, which has a great influence on the yield and quality of cotton. The disease usually begins at the early flowering stage. If the disease is not prevented and treated in time, the area of the disease will expand from the full flowering stage to the bolling stage, and the disease will be aggravated. At the beginning of the disease, the leaves showed dark green, then gradually thickened and wrinkled, brittle, yellow spots appeared between the veins, and the veins were still green. with the aggravation of the disease, the edge of the leaf began to roll down, and withered and fell off from yellow to purplish red until the cotton plant was completed and withered.

The main causes of cotton red leaf disease are barren land, hardening of cotton fields and poor ventilation; the other is that improper fertilization causes root injury, which affects the deep insertion of main roots and reduces stress resistance; another is that the root disease occurs seriously at the seedling stage and the function of absorbing fertilizer and water is weakened; the fourth point is the interplanting of wheat and cotton, the soil can not be ploughed all the year round, the tillage layer is shallow, and the nutritional area of cotton roots is small.

From the perspective of the cause of cotton red leaf disease, in order to prevent the occurrence of the disease, we must first apply reasonable fertilization, apply sufficient base fertilizer, re-apply flower and boll fertilizer and cover fertilizer, and increase the application of organic fertilizer and potassium fertilizer to achieve a reasonable proportion of nitrogen, phosphorus and potassium. During the cotton growing period, if it is found that the leaves of cotton plants have turned dark green, or the edges begin to turn yellow, the mixture of 0.2% potassium dihydrogen phosphate and 2% urea can be sprayed on the leaves, and the heavier ones can be sprayed twice in a row. When the air humidity is high after rain, it often aggravates. At this time, 0.2% potassium dihydrogen phosphate should be sprayed on the sunny day, which can inhibit the occurrence of this disease to a certain extent.

Secondly, shallow and medium ploughing should be done at the right time. Ploughing frequently, especially in times of drought, should be done in time to reduce soil water evaporation and enhance the stress resistance of cotton plants. Ploughing should also be done in time after rain to destroy soil consolidation and improve soil ventilation.

In addition, water should be irrigated in time. The bud and boll period is the most exuberant period for cotton growth, which requires a lot of water, so it should be watered immediately in case of high temperature and drought. If these measures are achieved, the occurrence of red leaf disease can be reduced or suppressed.