In the field of agricultural technical services to farmers, it was found that many blocks of cotton fields appeared light or heavy lands with premature aging. Through communication, it is known that many rural households either did not find out about premature aging of cotton in their own farmland, they did not pay attention to premature aging of cotton, and some farmers found out about premature aging of cotton, but they did not know how to prevent and remedy the problem. There were even some farmer household errors. The premature aging of cotton is considered to be premature cotton.
1, cotton premature death symptoms
Even the best cotton varieties, if not supported by scientific cultivation and management techniques, are prone to premature aging and related problems. There are many causes of premature aging, which have different degrees of impact on the yield and quality of cotton. To seize the high quality and high quality of cotton, the most important part of management in the middle and late period is to prevent premature aging.
Most of the premature aging of cotton occurs from late August to early September. After the growth of cotton plants enters the flowering and boll stage, because the absorption capacity of the roots is weakened, more water and nutrients in the ground cannot be supplied, especially when the cotton enters the flowering stage and the growth center shifts to the reproductive organs such as the bud bell, the reproductive organs of the bolls and other bells Competing with the vegetative organs for the organic nutrients produced by the leaves further inhibits vegetative growth.
At this time, the cotton plant has a certain number of cotton bolls in the middle and lower parts, and the upper cotton plant can have more than 90% of the red stem, the growing point becomes sharp, the flower position moves upwards, the top flower buds lurk, and no longer extends a new fruit branch. The number of layers of fruit branches is 2 to 4 layers less than normal; root failure, less roots and shallow roots, the ability to absorb fertilizer and water is greatly reduced; leaves are thin and yellow, buds are small, flowers are weak, peach is small, shedding of the bells is increased, the clothing is low, and the quality is changed Bad seed has poor maturity.
2, many causes of premature aging of cotton
The root cause of premature aging of cotton is the poor nutrition of the cotton plant during the boll opening period, resulting in premature aging and death of the cotton plant. Causes of premature aging of cotton plants are more common in the following types.
Fertilization is irrational. August is the period of heavy flowering and ringing of cotton, which is the key period for cotton to reach high yield, and it is also the peak period of cotton for fertilizer. If the bell and peach fertilizers are insufficient or not applied at all, the contradiction between vegetative growth and reproductive growth will be exacerbated, the upper fruit branches will not expand, the cotton leaves will fall rapidly, and the stamina will be insufficient. Especially in early-onset cotton fields, because of sitting earlier, the load is heavier and it is more prone to premature aging.
In the flowering and bolling period of cotton, the deficiency of potassium fertilizer is very harmful. Potassium deficiency in cotton fields will reduce the utilization rate of nitrogen fertilizers by cotton plants and reduce the boll weight; it will also reduce the resistance of cotton plants to brown flesh wilt disease; in particular, it will cause early leaf scorch and fall off. Deficiency of potassium can cause serious disease of red leaf blight in cotton field, causing a large number of leaves to fall off and premature aging. The disease can easily occur even in the case of adequate nitrogen and phosphorus fertilizers. Special attention should be paid to the fact that the transgenic hybrid insect-resistant cotton that is currently grown is very sensitive to potash fertilizer, and the amount of potash fertilizer needs to be more than double that of conventional cotton.
In addition, boron, calcium, magnesium and other trace elements can promote the growth and development of cotton roots and improve the root absorption function. If not, it will lead to poor root development and premature aging.
The weather is abnormal. Drought or waterlogging in the early stage of the bud can cause severe root development, resulting in irreparable root damage. In the middle and late periods, when there is no drought or drought, if it is not treated with irrigation or drought, the absorption and utilization of fertilizers will be difficult, and nutrition will not be able to keep up. In the middle and late growth period of cotton, it may cause diseases such as angular spot, melasma, brown spot, and epidemic disease to infect the leaves, which may cause premature failure due to impaired leaf function and photosynthesis.
Insect pests. Diseases and insect pests can cause premature senescence, especially in the case of Verticillium wilt and cotton fields that are seriously damaged by red spider, cotton aphid, cotton bollworm, etc., vascular bundles transported by nutrients are damaged, cotton leaves are damaged, organs that produce and transport nutrients are damaged, premature aging It goes without saying.
other factors. Early planting of early maturing varieties artificially advances the growth period, causes the root senescence period to meet with the blooming and ringing period, and causes premature senescence; early sowing in case of late spring, low temperature, slow root growth and serious disease, easily lead to late nutrition supply If it does not occur, premature senescence occurs. Severe storms cause serious lodging of cotton plants and damage to the root system, which can also cause premature aging.
3, cotton premature aging prevention and treatment
In recent years, the occurrence of premature aging of cotton is more common and occurs earlier and more serious. It has a great impact on the yield and quality of cotton. At the same time, there are many factors that cause premature aging of cotton, and there are many potential factors. Therefore, Prevent premature aging of cotton can not wait until the premature aging occurs and then "repair," and should be prepared to take preventive measures in advance.
Strengthening the management of fertilizer and water in the middle and later stages is an effective measure to control premature aging of cotton fields. It is suggested that the cotton farmers have less base fertilizer or less fertilizer in the first stage. At present, cotton plants show weak growth, thin leaves, and weak leaf-colored cotton-fed cotton fields. When the cotton is in bloom, early measures are taken to prevent cotton from occurring. Premature aging.
Fertilization management. According to the seedling condition, climate and land use, the flower and bell fertilizer should be reused. The best time to top-dressing top-covering fertilizers is from the end of July to the beginning of August. For pre-fat varieties with fusible peaches and podocarpus, sand-heavy soils, low-lying water-stained soils, barren soils, and relatively thin stems should be topdressed. Topdressing must be completed before August 15th, and can be applied in the middle of the big cotton line. Don't be too close to the roots to avoid rooting and causing premature aging. The occurrence of red leaf blight is the main cause of premature aging of cotton, and the disease is mostly caused by a more severe lack of potassium in the soil. At the same time, it should be applied at the bud stage with potassium sulfate or potassium chloride 5 to 10 kg. . After the cotton enters the blooming period, the root activity is weakened and the ability to suck up fertilizers is poor. The timely spraying of urea on the middle and late stages of cotton has a rapid effect and a high fertilizer effect, and has obvious effects on preventing premature aging, reducing shedding, and increasing the weight of the boll.
Drip management. The flowering and bolling period is the peak water demand of cotton (45% to 65% of the total water requirement) in a lifetime. If the cotton plant is growing well in the early period, the water shortage will cause premature aging and if the rain falls continuously, Susceptible to premature death. Hot and hot weather should be observed. If cotton plants are found to have a hiccup at noon, they should be watered in time to conserve the root system, improve the nutrient transport of cotton, and ensure that the fertilizer effect is played in time.
Do a good job of pest control. The functional period of normal leaves is generally about 8 weeks, but due to pests such as cotton bollworm, cotton aphid, cotton aphid, and spider mites, and diseases such as wilt disease, verticillium wilt, and red leaf blight, the leaves are damaged or fall off. The function of the blades accelerates premature aging. Therefore, we must control insect pests, reduce disease, and extend the function of the leaves.
Timely control. Adhere to "a small number of times, before light and heavy," the principle of the application of Dian Ji amine.
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