6 key points to grasp in cotton square-stage management

Proper watering: since rainfall in northern China is relatively low in mid-to-late June and the weather is hot, water appropriately, but do not overwater, so as to avoid excessive vegetative growth of cotton that causes squares to drop. After watering or heavy rain, cultivate the soil promptly to encourage the plant roots to grow downward.

Topdressing to promote weak plants: generally apply 5-6 kg of urea, 15-20 kg of potassium chloride, 1 kg of zinc sulfate and 1 kg of borax per 667 sq m to help the plants build a good high-yield framework. When fertilizing, the fertilizer should be placed in furrows about 15 cm from the plants and applied deeply. Topdressing at the square stage should take care of weak cotton seedlings and promote weak seedlings to upgrade.

Scientific pruning: pruning should adopt the method of retaining leaf branches; when 2-3 fruit branches have grown on a leaf branch, promptly remove the growing tip of the leaf branch to promote squaring, flowering and boll setting. Generally carry this out once around June 20, removing 4-8 early buds from the lower 1-4 fruit branches of the cotton plant, or removing the lower 2-3 fruit branches of the cotton plant. Adjust the flowering period to around July 10, and do not keep pre-dog-days bolls. Make the peak boll-setting period of cotton and the high photosynthetic efficiency period of cotton leaves coincide with the local high temperature, abundant light and abundant water period.

Intertillage and hilling: when the soil becomes compacted, or after watering, rain or snow, cultivate the soil promptly. Intertillage at the square stage should be deep, with a depth of 8-10 cm being appropriate. For cotton fields with a tendency to excessive vegetative growth, the intertillage depth can be increased to more than 10 cm to cut some lateral roots, reduce the number of root groups and control stem and leaf growth.

Timely chemical regulation: chemical regulation should follow the principles of "small amounts many times, spray vigorous plants but not strong plants, spray waterlogged fields but not dry fields, spray fertilized fields but not poor fields" to avoid phytotoxicity. Generally starting from the square stage, use mepiquat chloride for chemical regulation 4 times in total, but the start date and the dosage each time are not the same, mainly depending on the conditions of each cotton field; the first chemical regulation uses 0.1-0.5 g per 667 sq m; the fewest number of chemical regulation treatments is 3, and the most is 6.

Pest control: the main pests occurring in cotton at the square stage include second-generation cotton bollworm, cotton aphid, red spider and plant bugs. In future control work, remain vigilant against second-generation cotton bollworm. Second-generation plant bugs must also be detected promptly and treated promptly; the adults migrating into the cotton field should be killed before egg laying, and control work should be done in advance to avoid damage.