Heavy Rainfall Invades Southern China&Nbsp; Affected Cotton Production

Since the middle of May, a high-intensity and long-term heavy rainfall has hit the southern region, affecting Cotton production , resulting in waterlogging of cotton fields to varying degrees Cotton production Bring adverse effects. The national public welfare industry scientific research project team investigated the disaster situation in Jiangxi, Hunan, Hubei and Anhui provinces, and proposed management measures for decision-making reference.

1、 Overview of cotton field disaster

From May 13 to June 25, 60% of the cotton fields in Jiangxi Province were affected by heavy rainfall, covering an area of 500000 mu, of which 15%, 40% and 45% were cotton seedlings in the first, second and third categories of cotton fields, respectively; The area of crop failure was 100000 mu, and the cotton field of crop failure was changed to soybean, sesame, mung bean, corn and other crops. Since the middle of May, there have been five large-scale precipitation processes in Hubei Province: May 12-13, 15-18, 21-22, 26-28, June 7-8, and 23-24. The rainy days are more than 20 days, and the cotton fields are generally severely waterlogged. According to the monitoring, the cotton planting area of Hubei Province in 2010 was 7.5 million mu, the waterlogged area was nearly 40%, and the area without harvest was less. Since June, heavy rains have occurred in Hunan, especially in southern Hunan, with many times and most of the rainfall is rare in history. A small area of waterlogging disaster occurred in cotton fields. About 8000 mu of cotton fields in Lixian County were affected by waterlogging, of which more than 1000 mu were planted with rice, and the rest were less damaged. There was basically no disaster along the Yangtze River in Anhui.

2、 Adverse effects of waterlogging on cotton

The continuous rainfall from the middle of May to the end of June resulted in low temperature and lack of sunshine. The temperature was more than 2 ℃ lower than that in the same period of the year, the accumulated temperature in the growth period was more than 100 ℃ lower, and the sunshine hours in most areas were more than 20 hours less. The temperature in the middle and south of Jianghan Plain was lower than 20 ℃ for 9 days from May 13 to 22, and the "cold weather of awn seed" (the daily average temperature was lower than 22.0 ℃ for 3 consecutive days or lower than 20 ℃ for one day) occurred in the first ten days of June, which had a very adverse impact on cotton:

First, the birth period is delayed, and the growth is weak and uneven. Continuous rainfall leads to excessive soil moisture in the field, which is not conducive to growth; Long term low temperature and lack of light lead to insufficient photosynthesis and less dry matter accumulation, resulting in late emergence of stiff seedlings and slow growth. At present, about 60% of cotton seedlings in Hunan Province have not reached the budding stage, more than 15 days later than in previous years. Cotton seedlings grow irregularly, and there are 3~4 true leaves/plant and 20 cm height difference between cotton plants in the same hill block. Continuous rainfall also delayed the transplanting of cotton seedlings. About 20% of cotton seedlings in Hunan were transplanted in early June.

By June 24, there were 4~5 fruit branches of Class I seedlings in the middle reaches of the Yangtze River per plant, and no fruit branches of Class III seedlings had appeared. The growth time of late seedlings and weak seedlings lagged more than 20 days, and the proportion of Class III seedlings was more than 20% higher than that of last year.

Second, diseases, insect pests, weeds and waterlogging are serious. On the one hand, the climate of moderate temperature and high humidity led to the early occurrence of the "two wilts" disease, which was spreading with serious harm. According to the field survey, the incidence of cotton in Hubei Province is 7.9%~2.05%, the disease index is 4.6~22.8, and the death rate of serious fields is about 10%. In Lixian County, Hanshou County, Nanxian County and other places in southern province, the "two wilts" disease is serious. The incidence of some serious areas in Lixian County is about 20%, and the incidence of less serious areas is about 5%. On the other hand, the phenomenon of grassland hardening is very common. From May to June, there was a lot of rain, and most of the scattered wheat and rape sprouted and grew. The soil in the cotton field was barren and hardened seriously, and at the same time, it also bred insect pests. The blind bug elephant was more common in some cotton areas, and headless cotton and leaf breaking crazy were more common in some areas. Long term rain, low temperature and scant sunshine weather have delayed the harvest time of the previous crop of rape and wheat, and the field humidity is high, the soil is hardened, and cotton farmers are difficult to enter the field, resulting in the failure of measures such as weeding, scarifying, fertilizer application and ditch clearing, serious grassland shortage, and seedling stiffness.

Third, with the arrival of the plum rain season, the cotton production situation is facing a new test. Affected by the warm and humid air flow in the southwest and the cold air in the north around the subtropical high, the heavy rainfall belt in South China in the early stage will move northward to the Yangtze Huaihe River basin. Hubei Province has officially entered the Meiyu period since June 21, and there has been a strong heavy rain process in the province from 21 to 23, and there are two precipitation processes at the end of the month. On 26-27, there was a moderate rainfall process in most parts of the province; There was another rainfall process 30 days ago and 30 days later. According to the prediction of the meteorological department, the weather during this year's Meiyu period may be dominated by process rainfall, and the amount of Meiyu in most counties and cities is close to the multi-year average. Therefore, in the future, we need to stick to both flood control and drought relief. On the one hand, we should pay attention to preventing waterlogging caused by local heavy rainfall, On the other hand, it is also necessary to do a good job of moderate water storage and water conservation to prevent the impact of drought caused by less rainfall.

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3、 Remedial measures for waterlogging

At present, cotton has entered the budding stage in succession. Cotton production management should be based on disaster resistance, ditch drainage, water and fertilizer regulation, combined with measures such as intertillage, chemical control, pruning, etc., to promote the combination of control, achieve strong and stable growth, and build a good framework for high yield.

1. Bury the lodging cotton plants, wash the seedlings, open ditches and drain.

2. Grab the sunshine and plough in to break the knot. Grasp the sunny weather to hoe in time, intertillage and eliminate stubble, completely eliminate the grassland and harden, and provide good environmental conditions for cotton growth, especially in the oil stubble cotton field. At present, the scattered seeds have sprouted and sprouted, and should be removed as soon as possible. At the same time, the waist ditch, trunk ditch and enclosure ditch shall be cleaned to prevent the occurrence of waterlogging after entering the plum blossom.

3. Rush to apply bud fertilizer to promote erection. In the middle of June, the bud fertilizer will be applied again in combination with intertillage and soil loosening. The bud fertilizer should be combined with quick effect and slow effect. 30 kg compound fertilizer+10 kg urea+10 kg potassium fertilizer should be applied per mu.

4. Ridge and soil to prevent lodging. Attention should be paid to ridging and planting at different times, which is beneficial to prevent lodging and premature senescence when the density is low and the mutual lining ability between cotton plants becomes weak; It is also conducive to field drainage and irrigation.

5. Strengthen the prevention and control of diseases and insect pests. At present, the number of blind bugs, red spiders and aphids is high. For the "two wilts" and other diseases that have become a big occurrence in some areas, it is necessary to strengthen the field ditch clearing and drainage to reduce the waterlogging damage, timely control, and promote rapid recovery.

6. Categorized guidance focuses on chemical adjustment. In view of this year's complex seedling situation, we should give guidance by classification, and adjust measures according to the seedling conditions. Especially when the plum rain season is coming, the cotton fields with buds and normal growth should be blended with naphthylamine (or auxin) before entering the plum blossom, which can prevent excessive growth and increase shedding, and promote the growth of plants. The three types of weak seedlings should be mainly promoted, but the growth should be promoted under control.