What are the key measures for managing cotton during the flowering and boll-setting stage?
The main goals of cotton management during the flowering and boll-setting stage are: preserve bolls, increase boll weight, and prevent premature senescence.
1. Apply heavy flowering and boll fertilizer: The flowering and boll-setting stage is the period when cotton needs the most fertilizer throughout its entire growth period. For cotton fields with high soil fertility, abundant rain and good soil moisture, and vigorous cotton plant growth, topdressing can be done at the full flowering stage; for cotton fields with average soil fertility, drought and poor soil moisture, and weak cotton plant growth, early and heavy application should be done, with topdressing at the initial flowering stage. Generally, apply 15-20 kg of nitrogen-potassium compound fertilizer per mu. Continue to do a good job of intertillage and loosening the soil, following the principle of shallow rather than deep cultivation.
2. Water during drought, drain during waterlogging: If cotton plants grow slowly, leaves are dark green, and top leaves wilt and droop at noon on sunny days, irrigation should be done immediately; also note that after heavy rain, accumulated water should be drained promptly.
3. Careful pruning: This includes topping the main stem, topping the branches, and removing auxiliary buds. The time for topping the main stem should generally be in mid-July for ordinary cotton fields; for cotton fields with high water and fertilizer, low density, and vigorous cotton plant growth, it can be in late July, leaving 10-12 fruit branches. In early August, top the branches and remove auxiliary buds at any time. For densely shaded cotton fields, remove old leaves on the main stem from bottom to top in stages to improve ventilation and light conditions in the cotton field.
For cotton fields using the no-pruning technique, 2-3 leaf branches (vegetative branches) have already been left on the lower part of the main stem. The timing of topping the leaf branches should be appropriate. Topping method: when the first leaf branch has grown 3-4 fruit branches, remove the tips of all leaf branches left on the entire cotton plant, and apply topdressing 5-7 days earlier during the flowering and boll-setting stage.
4. Use cotton chemical regulation technology: Chemical regulation plays an important role in regulating cotton growth, controlling excessive growth, and promoting root development. For cotton fields with excessive growth or a tendency toward excessive growth, chemical regulation can be applied. At the initial flowering and full flowering stages, the amount of mepiquat chloride used is 2-3 grams per mu, diluted with water and sprayed on cotton plants. At the same time, it can be mixed with pest control and fertilizer supplementation (potassium dihydrogen phosphate) for spraying.
5. Prevent and control pests and diseases: During the flowering and boll-setting stage, the main pests include summer aphids, cotton bollworms, and other pests, as well as diseases such as boll rot, which should be controlled promptly.