In 2008, Hubei Jianghan Plain suddenly encountered heavy rain in the middle and late August, resulting in the phenomenon of premature withering in some cotton fields, which caused a serious reduction in cotton production. The author and relevant experts surveyed statistics and learned that the area of ​​cotton fields that occurred at early time accounted for 30% to 40% of the area of ​​cotton fields, and the degree of occurrence varied. The average dead seedling rate caused by early fall was 35.9%, and the seriousness reached 70. More than %, and some have emerged slowly after the recovery, but also caused a serious cut in the cotton fields. According to a typical household survey, cotton fields that have already been heavily plucked and have a good harvest are expected to have a short-term occurrence. The rate of output reduction is generally 30%-50%, and serious cases are more than 70%. In order to prevent this kind of problem from happening in our province, the case is now described as follows: I. Symptoms of early blighting Symptoms Two heavy rains were successively dropped on August 15-16 and August 28 in Hubei last year. The rainfall amounted to more than 150 millimeters. After the rain, some cotton fields showed partial wilting of the whole plant. After the end of the day, it turned brown and brown with dead coke; some cotton plants wilted from top to bottom, and some gradually died, and some of them recovered, but they also caused serious reductions in yield; others also developed blue and dry after wilting. Second, the relationship between early drying and related factors 1. The association with the species. According to the investigation of 54 cotton varieties planted locally at the Qianjiang Experimental Station of Guoxin Cotton Research Institute, the average rate of dead seedlings after the rain was 39.5%, of which 9 species were below 10% of dead seedlings, accounting for 16.6%; 10% of dead seedlings. -30% of the 15 varieties, accounting for 27.8%; 23 varieties of dead seedlings were 70%, accounting for 42.6%; 7 varieties of dead seedlings were more than 70%, accounting for 12.9%. Under the same conditions, there were significant differences in the dead seedlings between the varieties. Generally, the dead seedlings with fewer bellies and longer growing periods were lighter. The dead seedlings with more bells and pods were heavier; the dead seedlings with strong ability to resist yellowing and wilt Lighter, more severe dead seedlings. 2. The relationship with the terrain. Many surveys have shown that the groundwater level is high (less than 1 meter), drainage is poor, and dead seedlings are heavy. 3. The relationship with fertilization. According to the survey, the topdressing of cotton is generally repeated during the flowering period, and the fertilization time is generally between July 15 and July 20, with a topdressing amount of 20-25 kg of urea, which is not significantly related to the occurrence of early dryness after this heavy rain. However, fertilization is insufficient, and the weak sandy cotton fields are heavier. Some cotton farmers have top-dressing fertilizers that are too late and top-dressing is too much, but they also have heavy crops after recovering from the rainy cotton fields. In addition, in the shortage of potash fertilizer in cotton fields, early death of dead seedlings occurred heavier. 3. Reasons for the occurrence of early drought The relevant experts discussed after discussion, and finally concluded that the cotton seedlings were caused by sudden rainstorms after the premature aging of cotton. Because the susceptible varieties, early maturing varieties, and bells were increased, The degree of premature aging, so dead seedlings are heavier, high groundwater levels and poor drainage are the leading factors for early death. Fertilizer is mainly a topdressing fertilizer (urea). After the recovery, the fertilizer is not yet completely dissolved. The sudden rain (or watering) suddenly occurs, and the local concentration of soil is too large. Not only can the cotton not absorb, but also the nutrient backflow will be caused. Withering, after the occurrence of this phenomenon, part of the plants can recover. The deficiency of potassium in cotton fields is caused by yellow leaf blight or red leaf blight, and most of these phenomena occur in fertilizer-deficit or malnutrition cotton fields. The lack of fertilizer cotton fields not only lacks potassium, but also lacks nitrogen fertilizer. Yellow veins appear between veins at the beginning of the disease and the veins remain green. The leaf margin is dry and yellow, yellow leaf blight; malnutrition cotton field nitrogen sufficient, due to the incidence of potassium, red spots appear between the veins in the initial period, veins remain green, leaf margin charred, the whole leaf gradually turns red, is the red leaf blight . The above diseases went from top to bottom, developed from the outside to the inside, and suffered drought after a long drought. The early stage of disease was very similar to yellow wilt, but no discoloration was found after cutting the stem. IV. Prevention and remediation of early-morning cotton fields 1. Use anti-mite and disease-resistant varieties. This is the basis for the prevention and treatment of early fall. The selection of varieties should be adapted to local conditions. Early transplanting should be carried out for varieties with longer growth periods, so as to avoid the rainstorm season at the peak of Chengling. For transplanting of wheat and rapeseed, good varieties with early maturity should be selected. Prevent ripening from affecting yield too late. 2. Open up the ditch and do a good job of drainage. The results of the survey showed that where the drainage works are done well, it will be light if there is a shortfall. In particular, the land with high groundwater level and high groundwater level can be drained through the soil to ensure smooth drainage after rain. 3. Take effective management measures to postpone root ageing. The most prosperous period of cotton root development is in the bud stage to the early flowering stage. The development of root system is gradually weakened after the bolling. Therefore, after the flowering, the field management of cotton is mainly rooted in cultivating roots, delaying the senescence of the roots and preventing the occurrence of early weeping. After flowering, the cotton should not be intensively cultivated, and the top dressing should adopt the principle of a small number of times. When the amount of top dressing is relatively large, it is appropriate to use it after rain or after pouring, and the high-yielding cotton field bolls with fertilizers are applied twice in two. , The first flower, once the bell is full, the dressing should not be too close to the root, deep in the middle of the ditch; in late July and early August the cotton will enter the peak period of the bell, cover the top fertilizer 5-7.5 kg per mu. . In order to reduce the burden on the root system, foliar fertilizer is sprayed once every 7 days, and 2% of compound fertilizer is the best leaching solution. 4. Increase potassium fertilizer. In case of insufficient potassium fertilizer in the cotton field, the flower and bell fertilizers have to be made up. After entering the potassium-deficient cotton fields after August, 0.3% potassium dihydrogen phosphate is sprayed every 7 days. 5. Recovery and management after the occurrence of early death. After the occurrence of early drought, it is necessary to take corresponding measures according to the degree of occurrence and causes. First, drainage should be carried out to reduce waterlogging. For lighter, timely drying of peaches, removal of dead plants, and enhancement of air-ventilation intensity in the field, shallow drawing and drying. Reduce the humidity in the field and restore the normal growth of the undead cotton as soon as possible through field management. The flooding caused by fertilizer damage should be watered in time to reduce the field concentration and promote the normal growth of cotton plants. Waterproof Wound Dressing,Rectangle Big Wound Dressing,Waterproof Adhesive Wound Dressing,Medical Fixation Wound Dressing Surgimed Medical Supplies Co.,Ltd , https://www.surgimedcn.com