Technical Suggestions on Cotton Flowering and Boll Stage Management

The flower and boll stage of cotton is a critical period for both vegetative growth and reproductive growth, which gradually changes from vegetative growth to reproductive growth, with exuberant plant growth and large daily growth. it is not only the peak period of fertilizer and water demand in a lifetime, but also the key period for the formation of economic yield. it is necessary to take measures in accordance with local conditions and seedling conditions, and do a good job in pest control, chemical control, pruning and soil loosening. At the same time, reasonable and scientific fertilizer allocation, timely and appropriate irrigation can make plant individual growth steady, plant type and field population structure reasonable, ventilation and ventilation, strong light performance, developed root system, thick green leaf color, stable July, tender August, early September, more bolls and less shedding, and strive to achieve the management goal of "not only growing, not premature senescence, more bolls, less rotten bolls" in the flower and boll period, so as to ensure high yield and harvest. This year, the precipitation in the seedling stage of cotton sowing in our city is timely, the soil moisture is sufficient, the seedlings in the field are complete, the seedlings are uniform, the seedlings grow healthily and grow well, but in the second half of June, there is no effective precipitation in the bud stage, and the temperature is high, the evaporation is large, and drought is short of moisture, which is disadvantageous to the growth of cotton plants. On June 30, moderate rain fell throughout the city, and the drought was alleviated, which was conducive to blooming and forming bolls. The management of flowering and boll stage should combine soil moisture, plant growth and soil fertility, promote and control, manage scientifically, prevent high temperature, drought, autumn waterlogging and diseases and insect pests, strive for more high-quality peaches, increase boll weight, and prevent boll rot, premature senescence and late ripening.

First, re-apply flower and boll fertilizer scientifically. The flowering and boll stage is the period when cotton needs the most fertilizer in the whole growth period. Reasonable re-application of flower and boll fertilizer is the key to high yield, so as to apply sufficient flower and boll fertilizer and cover fertilizer. For cotton fields with sufficient soil fertility, good soil moisture and strong cotton plant growth, flower and boll fertilizer can be applied with a small amount or delayed application at full flowering stage, generally applying 8-10 kg urea and 5-10kg potassium sulfate or potassium chloride per mu. For cotton fields with insufficient base fertilizer, poor soil moisture and weak cotton plant growth, flower and boll fertilizer should be applied early and re-applied at the early flowering stage, generally applying 10-15 kg urea + 5-10kg potassium sulfate or potassium chloride per mu. For the cotton fields with excessive fertilization, vigorous growth and daily growth of more than 3 cm, topdressing at flowering and boll stage should be postponed to 1-2 bolls, and the amount of nitrogen fertilizer should be reduced appropriately. After topping, apply 5-7 kilograms of urea per mu as cover fertilizer. Topdressing is mainly applied in holes or strips, below 10 cm below the surface, 25-30 cm away from the cotton plant. At the same time, combined with the prevention and control of diseases and insect pests, 0.2% potassium dihydrogen phosphate + 1% urea + 0.2% borax mixture was sprayed for 2-3 times to quickly replenish plant nutrition, regulate plant nutrient structure, and reduce flower and boll shedding. From early July to early August, according to soil fertility and cotton plant growth, appropriate foliar fertilizer should be selected, top fertilizer should be added, plant nutritional status should be improved, functional period of green leaves should be prolonged, premature senescence should be prevented, boll weight should be increased, and early maturity should be promoted. 1% urea should be sprayed on cotton fields with weak growth, and 0.2% potassium dihydrogen phosphate solution should be sprayed on fields with strong and vigorous growth.

Second, timely irrigation and timely drainage. In the flowering and boll period of cotton in our city, there is more rainfall in general years, which can meet the water needs of growth and development in this period and affect the normal growth of cotton plants, but there is a great difference between years. In some years, there may be too much precipitation, resulting in water accumulation and waterlogging in low-lying fields, occasional lack of rainfall for a long time, poor soil moisture, resulting in a large number of buds and bolls falling off, fruit branches extending slowly, affecting yield. Therefore, corresponding irrigation and drainage measures should be taken according to weather change, soil moisture and cotton plant growth. Generally, there is no rainfall for 10-15 days, the relative water content of the plough layer of the soil is less than 60%, the leaves wilt and droop at noon, the leaves are thick, small, and dark green, and the fruit branches should be irrigated tightly when the extension of fruit branches is slow, and small ditch irrigation should be used to avoid flood irrigation; if the precipitation is too large, it should be drained in time to prevent soil hypoxia caused by stagnant water, root diseases and flower and boll shedding caused by excessive field humidity.

Third, ploughing and cultivating soil to prevent lodging. General cotton field ploughing should be shallow rather than deep, inter-row ploughing depth 7-10 cm, inter-plant depth 5 cm. For the cotton fields with the trend of overgrowth, proper deep and middle tillage should be used to cut off part of the lateral roots and control the overgrowth; after irrigation or precipitation, the soil should be ploughed and loosened, the field humidity should be reduced, the breeding of weeds should be reduced and rotten peaches should be prevented. In sandy soil, cotton fields that have not yet flowered and closed rows can be ploughed deeply and highly cultivated; cotton fields that have blossomed and closed rows can no longer be ploughed deeply in order to prevent excessive root damage and affect the growth of cotton plants. Combined with ploughing, reasonable soil cultivation can enhance plant lodging resistance, ventilation and light transmittance. The general height of the soil is 13-16 cm, and the final height is lower than that of the first fruit branch. When cultivating soil, you can not bury branches, hurt branches, or touch flower buds. Ridges and furrows should be straight to facilitate irrigation and later management.

Fourth, reasonable chemical control to restrain overgrowth. The appropriate chemical control time, chemical dosage and drug use times should be determined according to the precipitation and cotton plant growth, which should be controlled when the daily growth of the main stem is 2.5 cm in the early flowering stage and 3 cm in the full flowering stage. Fields with vigorous growth and strong plants should be sprayed with 1.5 grams of meth (or 5-10 milliliters) to 30 kg of water at the early flowering stage, and 40-50 kg of water with 2-3 grams per mu or 8-15ml at full bloom. The fields with poor growth should postpone the use of drugs or reduce the amount and times of drug use, generally using 2 grams of meth or 8ml per mu, and then decide whether to control it again according to the growth situation. Five days after topping in Wangchang cotton field, the weight of peach was increased by spraying 4-5g propionate per mu to inhibit ineffective buds, concentrate nutrients and increase the weight of strong peach. Attention should be paid to the fact that it can not be controlled for 5 days before and after topping, more rain is properly controlled, and drought is less controlled.

Fifth, fine pruning, reduce nutrient consumption, enhance ventilation and light transmittance. Adhere to the pruning principle of "fix branches with density, fix branches with different times, and branches with different times". The growing points of the lower 3 or 4 fruit branches should be knocked out at the early flowering stage, the growing points of 4 or 5 fruit branches in the middle should be knocked off around July 15, and all the tips of the upper fruit branches should be knocked off in early August. You can also hit the top of the group branches and the main stem at one time when there are enough fruit branches per plant in the cotton field with good growth (the number of fruit branches varies from variety to variety). The topping of cotton fields with poor growth can be postponed appropriately, but no later than the Beginning of Autumn, which is suitable for July 25-30. Cotton fields with high water and fertilizer, low density and strong cotton plant growth should be combined with topping and remove superfluous buds at any time. For the gloomy cotton field, the old leaves of the main stem can be knocked off by stages from the bottom up to improve the ventilation and light transmission condition of the cotton field.

Sixth, uncover the film in time to promote root downward extension. At the end of June or early July, combined with watering or soaking rain, the soil moisture was opened, and then the soil was ploughed and loosened to enhance soil permeability, promote root extension, improve drought resistance, and prevent lodging and premature senescence in the later stage. When the soil is dry and lack of moisture, it is not suitable to uncover the film, so as to avoid unclean film or root injury, which will affect the normal growth of the plant. After uncovering the film, 300-500 kg straw per mu can also be used to reduce soil temperature, reduce water evaporation caused by film removal and high temperature, which is beneficial to root growth, and at the same time achieve the effect of straw returning to the field to improve soil fertility and improve soil structure.

7. Closely monitor the dynamics of diseases and insect pests and do a good job of prevention and control in time. At present, the cotton varieties in the city are mainly insect-resistant cotton, the 2nd and 3rd generation of cotton bollworm generally do not need to be controlled, and the 4th generation is controlled according to the situation. And cotton aphids, blind bugs, red spiders have become the focus of prevention and control. Prevention and treatment should adhere to the principle of giving priority to prevention and scientific use of drugs. The mixed spray of two kinds of pesticides with different components should be selected according to the corresponding types of pests, and several formulations should be used alternately. At the same time, the dosage should not be increased at will to prevent pests from developing drug resistance quickly. Spray should be fine spray evenly, so that the back of the leaf drug, to prevent leakage spray, affecting the prevention and control effect.