How to manage the flowering and boll period of planting cotton

Cotton entered the flowering stage from the first ten days of July to the end of August and the beginning of September. The flowering and boll stage is not only the most exuberant period of cotton growth and development, but also the key period to determine the yield. Due to the high temperature this year, the growth process of cotton is generally fast, which lays a hidden danger for rotten bolls. Due to the different production conditions, the appearance of cotton fields and the ever-changing climatic conditions, the management of cotton flowering and boll stage should be classified according to local conditions.

First, fertilize the flowers and bolls well. For cotton fields with early flowering and severe drought, it is necessary to apply flower and boll fertilizer in combination with watering. Flower and boll fertilizer should be applied early in the early flowering stage, which is beneficial to more bolls. For cotton fields with good fertility and prosperous growth, fertilizer can be applied when sitting on one or two big bolls in the lower part of the plant. Flower and boll fertilizer should be re-applied, the general application of urea per mu is about 15 kg, and the bottom application of phosphorus and potassium fertilizer can be properly applied. The fertilizer of flower and boll should be applied deeply, and it is best to apply it below 10 cm in ditch after rain. Capping fertilizer can prevent premature senescence, shedding, more bolls and increase boll weight. Whether topdressing should be applied or not depends on soil fertility and cotton plant growth. For late-maturing cotton fields with sufficient fertility and strong cotton plants, saline-alkali land and clayey land, little or no top fertilizer should be applied to prevent greedy green late ripening, and early and more application should be applied to sandy land and cotton fields where cotton plants have a tendency of premature senescence. The top fertilizer is generally applied 3-5kg urea per mu, which is generally applied at the end of July and the beginning of August. In the middle and later stage of flowering and boll stage, the ability of cotton roots to absorb fertilizer and water gradually weakened, often due to insufficient nutrient supply, resulting in premature senescence. Foliar fertilizer spraying can effectively supplement nutrients and has a significant effect on increasing boll weight and preventing premature senility. Cotton fields with signs of premature senescence can be sprayed with 2% urea water + 0.5% potassium dihydrogen phosphate solution, usually 2 times from mid-August to early September.

Second, water the flowers and bell water well. When the soil water holding capacity falls below 70%, or the cotton plant grows slowly, the red stem rises rapidly, the leaf color is dark green, and the top leaves of the cotton plant wilt and droop slightly at noon, indicating that the cotton field is short of water and should be watered in time. The amount of water should not be too large, and at the same time, the field drainage project should be done well to prevent waterlogging and waterlogging damage caused by rain after watering.

Third, hit the flower bell branch. For cotton fields that bloom prematurely, the early flowers and young bolls before July 5 can be removed combined with pruning, which is beneficial to prevent premature senility and rotten bolls. The topping time should be adjusted to local conditions, generally around July 20; those with weak growth and wide row spacing can be advanced appropriately, strong growth, low density, and can be postponed to July 25; the topping time of pruning-free cultivation should be advanced to July 15, and the tops of main stems and leaf branches should be beaten thoroughly at one time.

Fourth, chemical control of flowering and boll stage. In general, high-yield fields, on the basis of chemical control at the budding stage, the second and third chemical control should be carried out according to the cotton growth in the flowering and boll stage. at this time, due to high temperature and humidity, the cotton plant grows vigorously, and each interval is determined according to the climate and the growth of the cotton field. generally, the interval is 10 to 15 days, 1 ~ 3 grams per mu, focusing on spraying the top of cotton plant and the top of fruit branches. The last chemical control should be carried out 7-10 days after topping, when the top fruit branches grow 3 fruit nodes, when the branches and leaves have aged, the dosage should be increased, generally 3 ~ 5 grams per mu.

Fifth, prevention and control of diseases and insect pests. The main pests in flower and boll stage are blind Toona sinensis, aphid, cotton bollworm and thrips, and the main diseases are Verticillium wilt, Fusarium wilt, ring blight, red leaf stem blight, boll blight and so on.