Technical Guidance on Late-Stage Cotton Management, issued by the Ministry of Agriculture in 2014
Cotton Expert Steering Group of the Ministry of Agriculture
National Agricultural Technology Extension Service Center
To strengthen late-stage cotton production management, based on cotton production conditions and climate characteristics in different cotton regions, with the goal of preserving bolls and increasing boll weight, strengthen late-stage fertilizer and water management, do a good job in disaster prevention and harm reduction, and go all out to secure a bumper cotton harvest.
I. Yangtze River Basin Cotton Region
The Yangtze River Basin cotton region is at the critical stage of autumn boll formation. All localities should make full use of the favorable late-season climate conditions of abundant sunlight and high temperatures, strengthen management, and strive for high yields.
(1) Scientific supplementary fertilization. According to cotton growth conditions, for cotton fields with late boll setting, few bolls in the middle and lower parts, and relatively vigorous growth, spray a 0.3% potassium dihydrogen phosphate solution for foliar application; for cotton fields where the upper fruiting branches of the cotton plant are short and growth is slow, timely foliar fertilization should be carried out to promote elongation of the upper fruiting branches; for cotton fields deficient in boron and potassium, timely spray boron fertilizer and potassium fertilizer to supplement late-stage nutrients, extend the functional period of leaves, and prevent loss of vigor and premature senescence.
(2) Strengthen field management. First, drainage to reduce waterlogging. All localities should pay close attention to weather conditions, timely clean and dredge field ditches, promptly drain accumulated water from cotton fields, and in case of typhoon and rainstorm weather, timely straighten and support cotton plants and loosen the soil at the appropriate time. Second, pruning and bud removal. For cotton plants with excessive vegetative growth and clusters of superfluous buds, timely pruning should be carried out to remove ineffective branches, leaves, and superfluous buds, and overripe bolls on the lower part of the cotton plant should be timely picked and dried to prevent boll rot. Third, spraying for ripening. For cotton fields with late development, many autumn bolls, and inability to normally crack and open bolls, according to weather and growth conditions, it is advisable to spray ethephon for ripening when the boll stage is more than 45 days, the temperature is above 20°C, and 20 days before the first frost.
(3) Integrated control. Pay close attention to the occurrence of the fourth generation of cotton bollworm, the fourth generation of cotton mirid bugs, tobacco whitefly, and other pests, select the right pesticides, apply them promptly, and control at the appropriate time.
(4) Timely harvesting. Normal cotton bolls are best harvested 5-7 days after boll opening. In the processes of seed cotton harvesting, drying, and packaging, attach importance to color grading, and carry out separate harvesting, separate drying, separate storage, and separate selling of white cotton and dull cotton, good cotton and stiff-petaled cotton, pre-frost cotton and post-frost stripped peach cotton, and normally opened cotton and contaminated cotton.
II. Yellow River Basin Cotton Region
Based on the cotton growth conditions in the Yellow River Basin cotton region, late-stage production should focus on increasing autumn bolls and timely harvesting, controlling the occurrence of premature senescence and late maturity in cotton fields, and strengthening fertilizer and water management to prevent boll rot.
(1) Fertilizer and water management. First, for cotton fields with premature senescence due to fertilizer depletion, spray 3% urea combined with 0.5% potassium dihydrogen phosphate solution or photosynthetic micro-fertilizer on the leaves. Second, field irrigation should depend on rainfall conditions and soil moisture; late-stage irrigation should not involve reopening furrows, and irrigation for high-yield fields and seed multiplication fields should continue until mid-September. Third, strengthen ditch cleaning and drainage to ensure smooth drainage and prevent waterlogging damage to cotton fields.
(2) Scientific management. First, for vigorously growing cotton fields and late-crop cotton fields, pruning and leaf removal are recommended to remove empty branches and old leaves and prevent field shading. Second, tall weeds and malignant weeds such as dodder should be timely removed, and plants should be pushed together into rows to increase field ventilation and light penetration. Third, for late-maturing cotton fields, ethephon should be sprayed according to weather and plant conditions; the spraying requirement is a suitable boll stage of 40-45 days, a temperature above 20°C, and the spraying time roughly 20 days before the first frost.
(3) Pest control. Increase control efforts against pests in cotton fields such as small brown planthopper, cotton mirid bugs, tobacco cutworm, and beet armyworm, do a good job in unified prevention and control, and reduce the probability of large-scale pest and disease outbreaks in cotton fields caused by factors such as high temperature and drought and excessive vegetative growth and late maturity of cotton plants.
(4) Reasonable harvesting. First, normal cotton bolls are best harvested 5-7 days after boll opening, and harvesting should use a cotton cloth bag. Second, in harvesting, drying, packaging, and storage, attach importance to seed cotton color; in practice, carry out separate harvesting, separate drying, separate storage, and separate selling of white cotton and dull cotton, stiff-petaled cotton and white cotton, pre-frost cotton and post-frost stripped peach cotton, and normally opened good cotton and contaminated cotton. Third, the seed cotton drying yard should be kept clean, and harvesting, drying, and storage should control the mixing of “three fibers” into seed cotton to ensure raw cotton quality.
III. Northwest Inland Cotton Region
In response to the characteristics of late-stage cotton production this year, focusing on preserving bolls and increasing boll weight, with the goals of promoting the development of middle and upper bolls, preventing biting, rot, drying, premature senescence, and excessive vegetative growth and late maturity, strengthen cotton field management, pest and disease control, and pruning and ripening.
(1) Cotton field management
1. Normal cotton fields. First, stopping irrigation should not be too early, and urea should be applied as a topdressing in combination with drip irrigation to prevent premature senescence. Second, depending on leaf color and leaf function, spray urea or potassium dihydrogen phosphate foliar fertilizer.
2. Prematurely senescent cotton fields. First, ensure irrigation and delay stopping irrigation; especially at the time of cotton boll opening, soil water-holding capacity should be maintained at 55%-60% to prevent stopping irrigation too early. Second, apply additional boron, zinc, and micro-fertilizers, and spray potassium dihydrogen phosphate on the leaves in the middle and late stages to prevent premature senescence of cotton. Third, use urea or potassium dihydrogen phosphate foliar fertilizer aqueous solution to spray once every 7-10 days, continuously spraying 2-3 times, which can achieve the effect of increasing boll weight and improving lint percentage and quality.
3. Management of excessively vegetative and late-maturing cotton fields. First, water control, reducing irrigation amount, extending irrigation intervals, and stopping irrigation earlier. Second, fertilizer control, reducing the total amount of fertilizer and the amount of nitrogen fertilizer. Third, manual pruning, removing side branches and secondary-growth branches, leaves, and superfluous buds; methods such as pushing plants together into rows can also be adopted. Fourth, timely application of ripening agents such as ethephon for ripening; before application, carefully read the pesticide label and operate according to regulations.
4. Management of machine-picked cotton fields. Spraying defoliants should follow the principle of appropriate dosage; it is more suitable to spray when the top cotton bolls are basically mature, more than 80% of bolls have reached more than 45 days, and the temperature is stable at 18-20°C; defoliation and ripening agents must be sprayed 18-25 days before harvest.
(2) Integrated control. Focus on the control of verticillium wilt, cotton bollworm, red spider mite, and other pests and diseases. When controlling pests such as cotton aphid and cotton bollworm, attention should be paid to mixed pesticide use and rotating pesticide use.
(3) Reasonable harvesting. For hand-picked cotton, focus on the “four separations” and strictly control the mixing of “three fibers” into seed cotton; for machine-picked cotton, harvesting can only be carried out when the defoliation rate in the cotton field is above 90% and the boll opening rate is above 95%; after mechanical harvesting is completed, manual field cleaning should be carried out promptly to reduce losses and waste.