What are the key technical points for cotton boll stage management?

The period from flowering to boll maturity and boll opening in cotton is called the flowering and boll stage. In general cotton fields, from early July to early September, cotton growth during the flowering and boll stage still involves both vegetative growth and reproductive growth proceeding simultaneously, but gradually shifts from vegetative growth dominance to reproductive growth as the main focus. The main direction of management in this period is to increase the setting of three bolls. Its management techniques mainly include five aspects.

1. Heavily apply flowering and boll fertilizer, and supplement with top-covering fertilizer. The fertilization time is at full flowering when 2 mature bolls have set on the lower part of the cotton plant. Generally, apply 10-15 kg of standard nitrogen per mu. If soil fertility is poor, cotton plant growth is weak, and soil moisture is poor, the flowering and boll fertilizer should be applied early, heavily, and with water. Achieve "apply at flowering for boll use." To prevent premature senescence, strive to set autumn bolls, and increase boll weight, for cotton fields showing a trend of fertilizer deficiency and premature senescence, apply about 5 kg of standard nitrogen per mu from late July to early August. In the later stage of cotton, because root absorption capacity weakens, foliar spraying can be adopted, spraying 2-3 times with potassium dihydrogen phosphate or urea aqueous solution.

2. Timely drainage and irrigation. In this period, the Huaibei region is often in summer drought, so watering should be done at the right time according to weather conditions, soil moisture, and cotton plant growth status. Our province has recently had continuous overcast and rainy weather, insufficient light, and water accumulation in some fields, so ditches should be cleared and drained in time to reduce field humidity and alleviate damage to cotton bolls.

3. Timely and careful pruning. General fields should be topped in late July to control apical dominance, avoid ineffective fruit branches, concentrate nutrients for bud and boll growth, improve field ventilation and light penetration, reduce bud and boll shedding, increase boll weight, and promote early maturity. Topping should remove 1 leaf and 1 top. For cotton fields with vigorous later growth, when there are many late buds and ineffective flower buds on the upper fruit branches, manual removal of side tips can be used to remove late buds, and flower leaves should be removed in time, empty branches cut, and redundant buds wiped off.

4. Reasonably implement chemical regulation. During the flowering and boll stage, spray 1-2 times with plant growth regulators such as mepiquat chloride to regulate the transport and distribution of nutrients in the cotton plant, enhance photosynthetic capacity, simplify later pruning, and prevent excessive vegetative growth and late maturity.

5. Strengthen the prevention and control of diseases and insect pests. The cotton flowering and boll stage is a period when various diseases and insect pests such as summer aphids, cotton bollworms, bridge-forming caterpillars, and red leaf stem blight occur and cause damage. Disease and pest forecasting should be strengthened, and integrated measures should be adopted for prevention and control to ensure a abundant cotton harvest.