What to Do After Cotton Is Flooded? Key Points of Emergency Management

In summer, rainfall is heavy, concentrated, and prolonged. At this time, cotton is in the most critical period of transitioning from vegetative growth to reproductive growth, and also the most critical period for the increase of cotton buds and bolls. To reduce cotton production losses and strive for a good cotton harvest, the following emergency management measures must be taken immediately after cotton is waterlogged.

1. Deeply dig three ditches. Quickly drain standing water and reduce water accumulation in the cotton field. Deeply dig the three ditches not only to drain standing water, but more importantly to lower the groundwater level and soil moisture content to relieve hidden waterlogging in the cotton field, and promptly clear the furrow ditches; the waist ditches must strictly meet the standards of 60 cm surface width, 30 cm bottom width, and 50 cm depth, with unified dredging and control. The waist ditches must be unobstructed, and the outlet must be deep so that all water can flow into the branch ditches; the branch ditches must promptly remove drainage obstacles to ensure unimpeded drainage.

2. Fertilize according to field conditions. Cotton after waterlogging is generally in two states: first, the waterlogging-controlled type, and second, the excessive-rain vegetative type. The waterlogged state must be strictly distinguished, and targeted remedial measures must be taken.

(1) Waterlogging-controlled type. This mainly refers to cotton fields with third-category seedlings and cotton fields flooded for more than 36 hours, where the cotton plants are stunted and do not grow, forming water-controlled conditions. For these cotton fields, apply quick-acting nitrogen fertilizer, with 10 kg of urea or 15 kg of diammonium phosphate per mu. (2) Excessive-rain vegetative type. Because cotton during waterlogging is often in the critical period of transitioning from vegetative growth to reproductive growth, long-term heavy rain inhibits the reproductive growth of cotton, causing excessive vegetative growth and forming a vegetative flush, with cotton plants growing leggy and serious shedding of buds and bolls. For vegetative-flush cotton, reduce the amount of fertilizer, especially quick-acting nitrogen fertilizer. Flower and boll fertilizer must be applied only after cotton growth weakens and 1-2 large bolls have set per plant. Because long-term flooding causes very serious loss of nitrogen, potassium, and micronutrient fertilizers from the cotton field, flower and boll fertilizer must be applied heavily. Apply flower and boll fertilizer per mu by burying 20-25 kg of urea, 15 kg of potassium chloride, and 1 kg each of boron fertilizer and zinc fertilizer, mixing them evenly and applying deeply in furrows. Combine fertilization with earthing up around the base.

3. Chemical regulation according to seedling conditions. For waterlogging-controlled cotton, chemical regulation should not be used during the water-controlled period. After fertilization improves the condition, chemical regulation should be light and carried out in small amounts multiple times. For excessive-rain vegetative cotton, chemical regulation should be used appropriately earlier and more often, so that plant height at flowering is controlled at about 50 cm, using 1.2-1.5 g of mepiquat chloride per mu, and carrying out chemical regulation during breaks in the rain.

4. Foliar topdressing. Waterlogging damage severely damages the cotton root system and blocks nutrient uptake. Through foliar topdressing, cotton nutrients can be quickly supplemented, the waterlogging resistance and flood tolerance of cotton can be enhanced, and the shedding of cotton buds and bolls can be reduced. Specific method: per mu, use 200 g of urea, 100 g of monopotassium phosphate, and 100 g of boron fertilizer mixed with 50 kg of water for foliar spraying. For foliar spraying, note that it should be done on cloudy days or in the early morning or evening of sunny days, and the concentration must not be too high.

5. Intertillage and earthing up. After long-term flooding, the cotton root base is very unstable and prone to lodging. At this time, the cotton plants must be quickly straightened and earthed up. When soil moisture conditions permit, quickly carry out intertillage and deep earthing up. Intertillage helps break soil compaction, promote root respiration, and accelerate root growth.

6. Disease and pest control. Promptly control the third generation of cotton bollworm, the second generation of pink bollworm, corn borer, aphids, red spider mites, and other pests. Take targeted measures against cotton Fusarium and Verticillium wilt, and prevent cotton boll disease in advance.

For fields that have already lost all harvest, do not wait and see; quickly replant short-season crops such as autumn corn, buckwheat, and vegetables to minimize losses as much as possible.