Beware of the outbreak of cotton red leaf stem blight after heavy rain

Recently, the cotton area has been raining heavily, and it is easy to break out red leaf stem blight for cotton after a long drought.

Red leaf stem blight is a physiological disease. It starts from the growing point of the main stem or the top of the fruit branch, and generally develops from top to bottom and from outside to inside. The main stem withers to death but the anatomical vessels are achromatic. The root system is thick and short, and the fibrous root is less poorly developed.

The reasons for the outbreak of red leaf stem blight of cotton are: extensive cultivation of cotton field, poor development of cotton root; poor drainage of cotton field; partial application of nitrogen fertilizer, vigorous growth of cotton field, shade of cotton field; and low organic fertilizer and poor soil fertility. Therefore, when the climate changes sharply, some cotton plants with poor cultivation environment and incomplete physiological function are prone to red leaf stem blight. To prevent and control cotton red leaf stem blight, the following points should be paid attention to:

I. Control the upper and promote the lower to enhance the resistance ability. One is to control the vigorous growth of cotton by applying plant growth retardant mepiquat amine or auxiliary strong element, spraying 2- 3g mepiquat amine or 8- 12ml auxiliary strong element on 50kg water per mu, which can effectively promote its stable growth; the other is to promote the stable growth of cotton fields with hardened soil, timely tillage and board breaking ventilation to enhance the performance of opening and showing; Third, for cotton fields with low terrain, attention should be paid at any time to tidying up ditches to promote cotton roots; fourth, for cotton fields with double film cultivation, the plastic film should be removed immediately to make cotton roots develop in depth.

Second, increase potassium fertilizer and improve fertilizer efficiency. Potassium deficiency was one of the main factors inducing red leaf stem blight of cotton. For the two types of cotton fields with potential potassium deficiency or less potassium application, 10-15 kg of potassium fertilizer should be added per mu. One can meet the needs of cotton for potassium fertilizer, and the other can adjust the fertilizer mix structure of cotton field. Improve the utilization rate of nitrogen and phosphorus fertilizer.

3. Spraying outside roots to improve oxygen and fertilizer absorption environment. Cotton with red leaf stem blight disease, as long as the cotton leaves have not withered, the main stem growth point still has vitality, and can be quickly restored to fertility function by topdressing. One is to spray 100ml of humic acid active liquid fertilizer Huimanfeng on 50kg of water per mu, which not only supplies fertilizer quickly, but also improves the oxygen supply status of soil; the other is to spray 100g of chemical fertilizer essence on 50kg of water per mu, which can supplement a large number of elements and trace elements; the third is to spray plant growth agent "802", which can accelerate cell division and enhance cotton self-regulation ability.