  Since the end of April to the beginning of June , the northwestern inland cotton region has an abnormal climate, low temperature and too much rain, especially in the northern Xinjiang, where the temperature is significantly lower and the night temperature is lower, showing a "cool and wet" weather feature. As a result, the current growth and development of cotton is slow, and the growth period is generally delayed by 5 to 10 days. In mid- May , the seedlings were worse than the same period of last year, and the number of seedlings in northern Xinjiang was worse than 20% in the same period last year. The proportion of weak seedlings and dead seedlings is large, and Wang Miao also has a certain area. By the end of May , large areas of cotton fields had not reached the standard of buds, and the area of ​​buds was small.
In view of the current problems of various types of late-onset and seedlings, the cotton expert guidance group of the Ministry of Agriculture suggested that due to the classification management of Tianyin seedlings, the use of cotton to have certain compensation ability for late development, promote transformation, and strive to achieve early maturity. High production. The main technical measures are as follows:
　  First, a reasonable division of the type of seedlings
The type of cotton in each field is classified according to the degree of lateness, the type of cotton field, and the growth of cotton. According to the actual situation, true leaves are classified into "late-wet weak seedlings" in the form of 3 to 4 pieces / plant, and plant height <20 cm; true leaves 5 to 6 pieces / plant, and plant height 20-25 cm are classified as " Late-onset and weaker type; true leaves 6 to 7 pieces / plants without buds, plant height >30 cm are classified as "late-starting seedlings" type; have reached the bud stage, plant height 20-30 cm is classified as " Basic normal seedling type.
Second, according to the classification of seedlings management
　　 1. "late and weak seedlings" and "late and weak" type to promote the main. It is recommended that such cotton fields adopt first promotion and post-control measures. That is, appropriate amount of water and nitrogen fertilizer, or use gibberellin and foliar fertilizer to promote growth and development, timely release of the film at the right time, combined with ketamine control after dripping ( application of ketamine 1.5 g / mu solution spray 1 to 3 times , each Once every 7 days).
　　 2. The type of "late hair sprouts" is controlled first. It is recommended to use ketamine light control first, combined with cultivating, timely film uncovering and other measures to coordinate nutrition and reproduction, and promote the transformation of vegetative growth to reproductive growth. Then, a small amount of early dripping water and appropriate amount of nitrogen fertilizer to increase potassium fertilizer to promote reproductive growth.
　　 3. Basic normal type. According to the normal management of this type of cotton field, it is necessary to pay attention to the combination of promoting and controlling, using ketamine, gibberellin and foliar fertilizer, combined with cultivating and other measures to regulate, increase the amount of potassium fertilizer, promote multiple buds, early flowering, and multi-quality bell.
Third, timely topping
Follow the principle of "when the branches are not equal, the time is not equal, the height is not equal", and the top is timely. When the cotton fields have premature fruiting branches 7-8 / plant, or plant height of more than 80cm, topping a timely manner; late cotton topping, southern no later than July 10, northern no later than the end of June.
Fourth, the prevention of pests and diseases
In the early stage, the control effect of cotton aphid was very good. The main pests and diseases such as cotton aphid, cotton bollworm, red spider, and verticillium wilt were to be strengthened. In particular, the cotton aphid, cotton bollworm and red spider are taken to prevent and control the spotted piece. In the early stage of the occurrence, the central plant is removed, the stem is coated, and the chemical control is performed, which can achieve good control effect.
　　 1. Risk Index of cotton aphid Control Index medicament spraying, the choice of 30% Saidan EC of 20 to 30 ml / acre, 50% methamidophos EC of 30 to 40 ml / acre, 20% permethrin or other speed off pyrethroid EC 10 to 20 ml / acre or 50% of carbaryl wettable powder 30 to 50 g / acre, water 20 to 30 kg / acre for control.
　　 2. Helicoverpa armigera can be used to kill adult insects by installing frequency-vibration insecticidal lamps in cotton fields, which can significantly reduce the density of eggs in the field. Per acre is usually installed an insecticidal lamps 60, above the crop lamp 50 cm, decoy time of 1 May to September. Chemical control options include 30% Sai Dan emulsifiable concentrate 1000 times solution, 2.5 % bifenthrin emulsifiable concentrate 3000 times solution, 1.8 % avermectin emulsifiable concentrate 4000 to 5000 times solution, 40% phoxim 1500 times solution, etc. .
　　 3. Cotton spider mites can be treated with 10% Liuyangmycin , 0.9% dextrovulin, 73 % ketone , 5% nisolan, etc., according to 1 : 2000 times the fixed liquid spray Prevention and treatment.
V. Disaster prevention and mitigation
　　 After June , it will enter the season of frequent disasters such as hail, strengthen monitoring and forecasting of severe weather, especially hail, establish a rapid response hail warning and artificial flood control mechanism, improve forecasting timeliness, and take emergency measures to minimize disasters. loss. After the disaster, it is necessary to timely cultivating and drying, urea solution + high-efficiency plant growth regulator + 3000 times of growth hormone foliar spray, a small amount of top dressing, and later spraying ethephon according to the situation.
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