According to investigations and on-the-spot investigations conducted by the National High-Quality Cotton Base Scientific and Technological Services Project Team, in recent years, the country’s area of ​​premature aging of cotton has become larger and larger, and the damage to production and quality has also been increasing. The rate of production reduction has reached 20%, and the severe decline has been achieved. 30%, severe crop failure. It is estimated that from 2003 to 2004, the output loss reached 400,000 to 500,000 tons because of premature senescence, and the economic loss reached 6 to 6 billion yuan, a reduction of 10%. Premature cotton not only reduced the production, but also reduced the quality of seeds and fiber. It can be seen that premature aging has become a major technical obstacle that restricts the improvement of cotton yield and quality improvement. The main reasons are as follows: First, it is caused by illness. In recent years, a major outbreak of wilt and verticillium wilt in cotton has been the main reason constraining the increase in yield. Since the onset of the climate response to the disease is very sensitive, as long as the temperature is below 30 °C in June-September, combined with high humidity, the mixed condition will quickly spread, which occurred in July-August, the most serious damage, due to slow recovery of the disease The biggest loss of output. It has been observed that the three major cotton regions show a trend of large outbreaks, with the Yellow River basin being the most serious. The outbreak time was for the first time in June-July; the second time was in August. Farmers said vividly that "cotton plants are disease-free for the rest of their lives." The main producing area has been continuously used as an old cotton field for many years, and the disease index is getting higher and higher, and the cotton plant “leaves and stalks†is even more serious. Variety of transgenic pest-resistant cotton disease is the most serious, the largest loss of output. In addition, in Xinjiang, the use of drip irrigation under the membrane has significant water-saving effect, but due to the long-term moisture in the cotton field, it is also easy to induce damage and decline. Because long-staple cotton is not resistant to wilt disease and leaf spot disease, it is prone to premature aging and its production is reduced by up to 50%. The second is the decline due to nutritional imbalance. Mainly due to "red leaf blight" caused by the decline. In the Yangtze River, the Yellow River and parts of northern Xinjiang, there is a large trend, mostly caused by soil malnutrition. Due to the slow growth of many transgenic Bt cottons and the lack of vegetative growth, topdressing with N fertilizers promoted growth. Because of the excessive use of N fertilizers, insufficient application of organic and potash fertilizers resulted in nutritional imbalance. Symptoms of premature aging are evident during the middle growth period and are accelerated in the later stages. In northern Xinjiang, as long as the low-temperature process from August to September is also prone to decline. The third reason is that the concentration of the bells caused failure. This is because some varieties of transgenic insect-resistant cotton are concentrated in the early and mid-term, and due to heavy physiological load, prone to premature aging in the event of drought and morbidity at the later stage. Fourth, due to the aging of the farming system and irrigation and water conservancy, it will cause decay. Premature ageing is also closely related to continuous cropping and no-tillage. This is due to a series of problems such as many years of farming systems, declining quality of farmland management, and aging of farmland and water conservancy. Long-term continuous cropping is another important cause of the decline of cotton. Because continuous cropping results in an increase in the cumulative amount of soil bacteria in cotton fields, it is extremely prone to decay. Adjusting the layout and rotation, promoting deep plowing, building irrigation and drainage fields freely, increasing organic fertilizers and potash fertilizers, selecting disease-resistant varieties, mulching and water-saving irrigation, strict quarantine and supplementing chemical agents, etc. The main technical measures for improving anti-microbial resistance, preventing premature aging of cotton, and seizing high yields are as follows: 1. Adjust production layout, promote rational rotation and deep plowing. Within a county within a suitable producing area and within a township, there should be plans for the purpose of shifting from a serious disease-producing area to a mildly ill place, from the diseased area to the non-disease producing area. For dry, verticillium wilt re-issued cotton fields, should be a reasonable rotation dumping. In the Yangtze River Basin, the cotton and paddy area is promoted, and the Yellow River Basin cotton area advocates wheat/maize, wheat/soybean and wheat/cotton rotations. The cycle of flooding, drought and drought is 3-5 years. In the area of ​​the Yangtze River, we will promote deep plowing, improve soil structure, promote root growth, and achieve a strong root. 2. Construct a high standard irrigation and drainage cotton field and implement deficit irrigation. On the basis of the construction of a high standard cotton field, irrigation and drainage can be performed freely. Due to the biological characteristics of cotton with drought tolerance, the amount of irrigation water and the number of irrigation can be appropriately reduced in severe cases. In drip irrigation, the continuous irrigation should be changed to intermittent irrigation to keep the cotton field dry and wet alternately. 3. Increase organic fertilizers and use chemical fertilizers in a balanced manner. Chemical fertilizers advocate the use of "reducing nitrogen and stabilizing phosphorus to supplement
Potassium fertilizer" to apply boron-zinc microelement fertilizer in boron-deficient and zinc-deficient cotton fields. To promote the application of potash fertilizer, it is recommended that the ratio of nitrogen and potassium in high-yielding cotton fields be 1:0.8-1. The promotion of foliar application of potassium dihydrogen phosphate in the middle and late stages has the effect of delaying the onset of diseases and promoting the rapid recovery of diseased plants. 4. Strict quarantine, control proliferation. First, strict quarantine, cotton seed species must be reduced by sulphuric acid to eliminate seed short-fed fungus and control disease spread over long distances. The second is to control the spread of sporadic disease fields, to remove sporadic diseased plants at the primary site of origin, and to burn them outside the field; to eradicate severe disease fields, use dot blots. 5. Complementary pharmaceuticals and biological control. The use of some biochemical and growth regulators, such as Greenwind 95, Betox, ABT4, Diaminos, Potassium Dihydrogen Phosphate, etc., can promote strong roots, help prevent disease intrusion, and increase resistance to diseases. .
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