Key Points for Cotton Production in the Late Stage

1. Northwestern Inland Cotton Region

In the Northwestern inland cotton region, the growth progress in the early to mid-stages was notably faster than in previous years. The proportion of early-stage bolls is high, and by late July, most cotton fields had reached the flowering stage, with some fields showing fiber development by early August, laying a good foundation for high yields. Late-stage management should focus on enhancing field management to improve harvest quality.

1. Strengthening Late-stage Fertilizer and Water Management: Apply water and fertilizer via drip irrigation 2–3 times, with a dosage of 30–40 kg per acre. Stop irrigation at the appropriate time; stopping too early or too late can affect boll development and fiber maturity. In northern Xinjiang and Gansu, stop irrigation in late August, while in southern Xinjiang, stop irrigation from late August to early September. Ensure soil moisture content stays around 60% to allow full seed and fiber development, increasing boll weight and preventing early cotton aging.

2. Pest and Disease Control: Focus on controlling cotton bollworm and spider mites. Use eco-friendly pest control methods and rotate pesticides to prevent spider mite hotspots and second-generation cotton bollworm infestations.

3. Defoliation and Ripening: Follow the principle of “timely defoliation, no waiting for fiber.” When the fiber exposure rate reaches 40%, apply defoliant during clear, windless weather with temperatures above 20°C. For fields with slow fiber exposure, spray defoliants in northern Xinjiang from late August to early September and in southern Xinjiang from September 10 to 15. Ensure the defoliation rate exceeds 92% and the fiber exposure rate exceeds 95% before machine harvesting.

4. Improving Harvest Quality: Before machine harvesting, clear fields of irrigation equipment, weeds, and residual film. Ensure fire prevention facilities are in place, and smoking or open flames are strictly prohibited. Harvesting should be done after 12 noon to ensure cotton moisture content is below 12%, with a picking rate of no less than 93%. Night harvesting, dew harvesting, or water-spraying harvesting are strictly prohibited to maintain cotton quality.

2. Yellow River Basin Cotton Region

This year, cotton growth in the Yellow River Basin progressed earlier than usual, with a high proportion of early-stage bolls. Most cotton fields have begun fiber exposure, with high boll formation rates in the lower and middle parts of the plant but low rates in the upper bolls. Late-stage management should focus on flood prevention, boll rot, and pest control.

1. Flood Prevention: In the event of heavy rain causing field flooding, drain the water promptly and support any fallen cotton plants to promote field drying.

2. Prevention of Boll Rot: Harvest exposed lower bolls promptly to prevent late-stage rainfall from affecting cotton quality. During prolonged rainy periods, support and align plants to increase field ventilation and prevent boll rot.

3. Pest Control: Major late-stage pests include mirid bugs and whiteflies. Use Flupyradifurone for mirid bugs and alternate pesticides with a 5–7 day interval. Use Thiamethoxam or Acetamiprid to control whiteflies. For large fields, coordinate pest control operations to ensure uniform application.

4. Ripening and Harvesting: In hand-picking fields, apply ethephon ripener at the end of September or early October when temperatures exceed 20°C. Use white cotton tools (cotton hats, cotton bags, etc.) to avoid contamination by foreign fibers. Machine-picking fields can apply a mixture of Thidiazuron and Ethephon ripener in late September, with machine harvesting in mid-to-late October.

3. Yangtze River Basin Cotton Region

In the Yangtze River Basin, prolonged high temperatures and drought in mid-to-late August have caused significant boll shedding in the middle and upper parts of cotton plants. The current focus should be on drought relief, boll retention, and growth regulation.

1. Timely Irrigation and Fertilization: For fields with surface cracks, use furrow, sprinkler, or drip irrigation depending on conditions. Avoid flooding furrows. Apply foliar fertilizers such as potassium dihydrogen phosphate and micronutrient solutions to promote boll retention and increase boll weight.

2. Growth Regulation: To ensure robust growth without overgrowth, use chemical regulators such as Mepiquat chloride in fields with excessive growth and high density, adjusting dosage and frequency as needed to improve ventilation and increase boll formation rates.

3. Pest Control: Late-stage pests include mirid bugs, cotton bollworms, and whiteflies. For mirid bugs, spray early in the morning or late in the evening using pesticides such as Avermectin and Malathion. Rotate pesticides for cotton bollworms and use Bifenthrin for whitefly control.

4. Ripening and Harvesting: In hand-picking fields, apply ethephon ripener in mid-October when daily temperatures exceed 20°C for 3–5 consecutive days. For machine-picking fields, apply a mixture of Thidiazuron and Ethephon when natural fiber exposure exceeds 40%, and harvest 15–20 days later.