What are the key technical points for cotton management after autumn

In autumn, cotton growth shifts to the late growth stage of boll opening and completing the development of autumn bolls. During this period, the focus should be on nurturing the roots and protecting the leaves, using scientific management methods to promote robust cotton plant growth, prevent premature aging as well as excessive vegetative growth and late maturity and rotten bolls, and strive for a bumper cotton harvest. The specific management methods are as follows:

1. Drought resistance and waterlogging prevention

No water means no fertilizer. If water is insufficient, cotton plants will produce large amounts of ethylene, leading to premature aging and shedding of cotton bolls. Therefore, from mid-August to mid-September, the soil moisture content in the 0-40 cm layer should be maintained above 55% of field capacity. Only in this way can the various physiological functions of cotton operate normally. If it falls below this threshold, water lightly or water every other row. Never flood irrigate or soak the field, so as to keep drainage in the cotton field unobstructed and avoid excessive water accumulation that affects root vigor. While preventing drought, also pay attention to waterlogging damage to cotton caused by excessive autumn rain. Timely clear ditches and drain water to protect the root system and reduce rotten bolls.

2. Intertillage and soil loosening

After rain or irrigation, the cotton field surface becomes compacted, permeability is poor, and root vigor declines. Use animal-powered shallow intertillage or manual hoeing (loosen the soil shallowly rather than deeply) to break up soil compaction, improve soil permeability, and promote cotton root growth. At the same time, combine soil loosening with hilling soil around the roots, which can effectively enhance the cotton's lodging resistance.

3. Foliar topdressing

Make full use of the absorption function of leaves to carry out foliar spraying of fertilizer, to make up for the deficiency in nutrient uptake by the root system, improve the photosynthetic capacity of leaves, and thereby increase the boll-setting rate of cotton. Apply flower and boll fertilizer heavily to meet the nutrient needs of cotton during boll setting; supplement boll fertilizer. When cotton forms bolls, it has a high demand for potassium fertilizer. Due to the consumption of large amounts of nutrients, many cotton fields show signs of fertilizer deficiency and premature aging. If nutrients are not supplemented in time, it is difficult to achieve autumn bolls covering the top; spray fertilizer at the right time to prevent premature aging. From August to early September, spray once every 5-6 days with a 1% urea solution, focusing on the underside of the middle and upper leaves. Spray after 4 p.m. on sunny days, and spray throughout the day on cloudy days. Never spray when the temperature is high and light is strong, to avoid excessive water evaporation after spraying, which causes a sudden increase in concentration and leaf burn.

4. Timely pruning, pushing rows together

Mainly remove old leaves and empty cotton branches from the lower part of the cotton plant, and remove the group tips of cotton branches. For cotton fields with lush branches and leaves and relatively high density, after rain, while the soil is still moist, also adopt the measure of pushing rows together, that is, push two adjacent rows of cotton together in a V shape, so that both sides of the pushed-together cotton receive sufficient sunlight, playing a role in ventilation, light penetration, warming, and reducing humidity.

5. Prevent excessive vegetative growth and late maturity

In the late growth stage of cotton, excessive population size, excessive or too late nitrogen fertilizer application, and overly vigorous cotton plant growth can easily cause excessive vegetative growth and late maturity, with an increase in late autumn bolls, causing cotton bolls to fail to open normally and affecting cotton quality. For late-maturing cotton bolls, spray ethephon solution for ripening. It should be sprayed around Cold Dew to Frost's Descent, when the average temperature remains above 20°C for 3 consecutive days and more than 80% of cotton bolls have reached 40 days or more.

6. Scientific pest control and disease prevention

Focus on the prevention and control of yellow leaf wilt disease, cotton bollworm, cotton aphid, and other pests and diseases. Yellow leaf wilt disease is a physiological disease accompanied by potassium deficiency and caused by malnutrition. Cotton fields lacking organic fertilizer, barren fields, and drought conditions can all lead to this disease. It can be prevented and controlled by supplementing potassium fertilizer and foliar spraying. Cotton aphids, cotton bollworms, and other pests all have strong pesticide resistance, so when controlling them, pay attention to mixed and rotated pesticide use.