What to do after cotton suffers hail damage
During the growth period of cotton, hail disasters occur every year. Although the scope is small, the damage caused is very serious. According to statistics, after 1980 in Shandong Province, the average area of farmland affected by hail damage was more than 5 million acres every year. Hail in the North China Plain occurs concentratedly from May to July, and the number of hailstorms accounts for more than 60% of the total number of occurrences, with more hail falling in June, followed by May, July and April.
Because cotton has the characteristics of unlimited growth, deep roots, hard stems, and strong recovery ability, if it is treated promptly after a hailstorm, it can still achieve considerable yields. Factors such as the degree of damage to cotton, the timing of hailstorms, and economic gains and losses must be comprehensively considered to determine the specific measures to be taken. Under normal circumstances, after cotton is hit by a mild or moderate disaster, management should be strengthened in a timely manner to achieve better economic benefits; cotton fields that are severely hit by hail before late May will be more profitable to replant with summer cotton, and those that are hit later will be more profitable to replant with summer corn. . Cotton affected by mild or moderate disasters should take the following management measures:
(1) Assault cultivating to loosen the soil. Hail is usually accompanied by violent storms, which not only directly damages cotton plants, but also causes soil compaction in cotton fields, high humidity, low temperature, and poor ventilation. After sunny days, the temperature rises quickly and is higher than the ground temperature. To save cotton, save the roots first. After the disaster, timely plowing and loosening of soil should be carried out. First, loosen the rhizosphere hardening layer of cotton plants, and then carry out loosening of soil between plants and cultivating between rows to ventilate and disperse moisture, loosen soil and increase temperature, so as to change unfavorable environmental conditions. , reduce root rot, meet the needs of root growth and development, and promote the root system to grow new roots quickly and resume growth. Cultivating should be shallow rather than deep to avoid damaging too many roots.
(2) Prevent and control pests in a timely manner. In the early stages of recovery of hail-damaged cotton, the leaves are small and the buds are tender, so they are afraid of aphids. After the disaster, it is necessary to promptly prevent and control cotton aphid damage. The growth period of hail-damaged cotton is delayed, and it becomes tender and vigorous late. The insect-resistant activity of insect-resistant cotton is also low. In the middle and late stages, the damage of cotton bollworm and Lygus gossypii is serious. It is necessary to investigate the insect situation in time and strictly control the control indicators to ensure the control effect.
(3) Carry out fat pursuit in a timely manner. In order to improve the nutritional conditions of hail-damaged cotton and promote the recovery of growth, 5 to 7 days after the disaster, when the physiological functions of the cotton plants have reached a new stable equilibrium state and most cotton plants have grown new buds, it is necessary to catch up in time. Apply nitrogen and phosphorus together, 15 to 20 kilograms of each per mu. Mixed application of nitrogen and phosphorus can improve the assimilation capacity of leaves and improve the operation and distribution of assimilation products. When the cotton reaches the peak flowering stage, apply 10 to 13 kilograms of urea per acre to accelerate growth in the middle and late stages, promote faster and more bolls, and increase yields.
(4) Reasonable pruning and pruning. For cotton fields with minor disasters where the top center of the cotton plant is not damaged but only leaves are damaged or fruit branches are broken, the main task is to remove the superfluous buds and leaf branches in time to keep the top buds growing normally; for cotton fields where the top center is damaged but there are broken leaves and a small number of fruit branches. For cotton plants, after new buds appear in the upper part, 1 to 2 strong buds can be left on the 5th, 6th, and 7th leaf positions of the main stem to replace the top buds; for severely damaged cotton plants with complete stalk decapitation, it is necessary to choose according to the hail disaster. Depending on the period, growth status, cotton field strength and seedling density, select an appropriate number of leaf branches in appropriate locations. For cotton plants that have been decapitated by hail before budding, select 1 to 2 new buds growing in the middle and upper part of the main stem, no more than 3; for cotton plants that have been decapitated by hail during the early flowering period, due to the limited growing season , should be based on the principle of protecting early buds and early bells, and carry out reasonable renovation. When most of the new buds begin to bud, remove the small buds without buds, select the big buds with big buds, and top them early appropriately, so that more buds can be obtained. Preserve effective early buds and increase effective bell formation. Regardless of the degree and period of the disaster, care must be taken to protect the leaves during pruning. Even damaged leaves have the function of producing nutrients. For cotton plants with completely decapitated stems, pruning can be done when the new shoots turn from yellow to green and the leaves open. Cotton affected by hail is late and late-maturing. In October, 150 to 200 ml of ethephon per acre can be sprayed to accelerate ripening, which will have a significant effect on increasing the flowering rate before frost.
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