Key Field Management Techniques for Cotton After Topping in July
After cotton topping, generally 1 to 2 chemical control applications are made. The first is 3 to 5 days after topping; for fields with about 12,000 plants per 667 sq m, apply 4 to 5 grams of mepiquat chloride in 30 kg of water;
After cotton topping in July, the following technical measures should be taken.
1. Scientific chemical control
1. Regulate according to growth vigor
After cotton topping, generally 1 to 2 chemical control applications are made. The first is 3 to 5 days after topping; for fields with about 12,000 plants per 667 sq m, apply 4 to 5 grams of mepiquat chloride in 30 kg of water; for fields with more than 16,000 plants per 667 sq m, apply 6 to 7 grams of mepiquat chloride in 40 kg of water. The second chemical control application depends on the individual development and population size of the cotton plants, and a moderate heavy control should be carried out according to the weather, soil moisture, and the growth vigor and appearance of the cotton plants; generally about 8 grams of mepiquat chloride per 667 sq m. Through the action of mepiquat chloride, the goal is ultimately to effectively control ineffective flower buds and the growing tips of empty fruit branches, realize the transformation from vegetative growth to reproductive growth, shape a growth vigor and appearance that ensures balanced yield increase, ensure an increase in the number of bolls set at the top of the cotton plants and in single boll weight, and create conditions for high yield.
2. Proper spraying method
The correct method for spraying mepiquat chloride is: first dissolve the mepiquat chloride in a weighed basin or plastic bucket container, stir thoroughly, and add it to the sprayer according to the amount of mepiquat chloride contained per 100 grams of mepiquat chloride aqueous solution.
Spraying mepiquat chloride should follow the principles of even but not overflowing, spraying the tall and not the short, and spraying the vigorous and not the weak, and it is best done after 5 p.m. Spraying under high temperature and strong light will reduce the effect; if rain occurs within 6 hours after spraying, it will affect the absorption effect; if the rainfall is heavy and lasts a long time, it will be ineffective and re-spraying is needed.
2. Irrigate according to local conditions
After cotton topping, cotton enters the peak period of reproductive growth, and flowers, buds, and bolls gradually form. This stage is the stage with the highest water demand in the entire growth period of cotton. For cotton fields with conventional furrow irrigation, the first irrigation should be light, the second should be full, and the third and fourth should be sufficient (the third and fourth irrigations are the two irrigations after topping). Irrigation must be stopped before August 15 to prevent the cotton plants from remaining green and late maturing.
3. Fertilize according to plant appearance
After topping, cotton needs more water and fertilizer. For cotton fields under conventional irrigation, different amounts of nitrogen, phosphorus, and potassium fertilizers are applied as base fertilizer and at the time of the first and second irrigations. After topping, nitrogen fertilizer should be applied as a supplement according to the branch and leaf appearance of the cotton plants, applying 5 to 8 kg per 667 sq m. At the same time, foliar boron fertilizer should be additionally sprayed; dissolve 50 grams of Sule boron in 50 kg of water per 667 sq m and spray, for a total of 2 sprays, to increase the boll-setting rate.
4. Timely harvest
After boll opening, cotton picking should adhere to the "three whites," and carry out graded picking, graded stacking and sun-drying, and graded selling, to ensure cotton quality and quantity and a bumper harvest.