How to prevent premature senescence in cotton? Cotton farmers learn these three methods
Entering July to August is the peak period of massive flowering and boll setting in cotton, the key period for cotton yield formation, and also the peak period of cotton fertilizer demand. If fertilizer cannot keep up during this period, cotton will suffer premature senescence due to fertilizer deficiency, causing massive shedding of squares and bolls, resulting in substantial yield reduction and serious losses. Therefore, for cotton fields with insufficient base fertilizer or relatively little topdressing in the earlier stage, where cotton plants currently show weak growth vigor, thinner leaves, and pale leaf color due to fertilizer deficiency, the “three” yield-increasing measures to prevent cotton premature senescence should be well implemented during the peak flowering and boll-setting period.
1. Timely supplementary application of topping fertilizer. The best time to apply topping fertilizer is after topping the growing point, from the end of July to the beginning of August. Apply 5--7.5 kg of urea per mu, combined with intertillage and earthing up, hoeing it into the large row spaces of cotton, at a depth of 10 cm, about 15 cm away from the cotton plants. This topdressing has a significant effect on increasing stamina and preventing premature senescence in cotton.
2. Timely spraying of foliar fertilizer. Spraying foliar fertilizer on cotton should begin after topping, and at the latest before the Start of Autumn solar term (August 8), foliar fertilizer should be sprayed in time to supplement nutrients. After cotton enters the peak flowering and boll-setting period, root activity weakens and root absorption capacity is poor, so soil topdressing has poor effect. Therefore, timely spraying of foliar fertilizer in the middle and late stages of cotton has quick results and high fertilizer efficiency, with obvious effects on preventing premature senescence, reducing shedding, and increasing boll weight. Methods for spraying foliar fertilizer: (1) Spraying foliar fertilizer alone: such as potassium dihydrogen phosphate, Ainong and other good foliar fertilizers. (2) 1--2% urea solution + 0.3% potassium dihydrogen phosphate solution. (3) 1% urea solution + 2% phosphate fertilizer extract. (4) 1% urea solution + 2% phosphate fertilizer extract + 2% potassium chloride solution. Spray 50--60 kg of mixed solution per mu each time, spraying the whole field, once every 7 days, for 3--4 consecutive times. When spraying, do it after 5 p.m. on windless days; on cloudy days, spray all day, focusing on the underside of leaves to facilitate absorption.
3. Grasp both drought resistance and waterlogging prevention, and persist in fighting disasters to secure a bumper harvest.
After cotton enters the peak boll-setting period, it fears both drought and waterlogging. During the flowering and boll-setting period, when there is drought, if there is no rain for 10--15 days, cotton will suffer from drought. If the weather forecast shows no rainfall in the near future, irrigation should be carried out immediately, using alternate-row furrow irrigation, and absolutely avoiding flood irrigation, to prevent waterlogging caused by rain after irrigation. After irrigation, shallow intertillage should be carried out in a timely manner to break soil compaction and help preserve soil moisture.
After heavy rain, promptly drain the standing water from the field, and drain it no later than 24 hours, to prevent waterlogging, which can cause cotton root suffocation, root rot, yellowing leaves, leaf drop, and massive shedding of squares and bolls. Also carry out timely hoeing and shallow intertillage to ensure good soil aeration, smooth root absorption, and normal cotton growth.
For cotton fields with no standing water after rain but with waterlogged damage due to heavy clay soil, dig ditches in the large row spaces of the cotton field to allow water to seep away, reduce surface humidity in the cotton field, improve the suitable growing environment for cotton in the later stage, and strive to set more cotton bolls, grow large bolls, prevent rotten bolls, and secure a bumper cotton harvest.