Grasp the time and methods of chemical control of cotton

Although the sowing of cotton is late, the development of cotton seedlings is also late. By the first ten days of June, the well-growing cotton fields in the north have now had 7 to 8 true leaves, and some have already budded. Around June 10, most cotton fields will enter the budding stage one after another. On June 10, most cotton fields have three fruit branches, but this year there will be two less fruit branches, and there will be no peaches or fewer peaches, which is not necessarily a bad thing. It can save the work of removing early buds and 1 or 2 fruit branches in the lower part, which is conducive to reducing rotten bolls and stiff bolls.

According to the investigation results of Guoxin cotton plant, the fastest growth period of cotton main stem is from June 10 to July 10, with an average daily growth of 1.5 cm, and it is also the peak period of root growth at this time. If the aboveground grows too fast, it will affect the root growth, resulting in the imbalance of aboveground and underground growth, and is not conducive to the control of plant height. Therefore, most cotton fields should be sprayed for the first time in mid-June.

The specific day to start chemical control, mainly depends on the growth of cotton seedlings. For cotton fields with fast development, large leaves and high plant height, it is appropriate to start in early June. large leaves of cotton seedlings indicate that vegetative growth is prosperous, and chemical control is necessary, and the effect of chemical control mainly depends on chemical dosage. generally, 0.3 ~ 0.5 grams per mu of cotton field is used, and the cotton field with prosperous growth should be added, and the concern of chemical control in bud stage must be eliminated. Once the chemical control is late, it will cause passive management. Specifically, it is necessary to master the following points:

First, select the national standard, that is, the effective ingredients are more than 97% and the impurities are less than 1.5%. Do not use other chemical control drugs that do not indicate the content of impurities and unknown ingredients. In the past, the problems in the chemical control of cotton farmers, either ineffective or overweight, were caused by unqualified propranolol or regulators with unknown ingredients.

Second, spraying must make the cotton tip transfer very slowly because the cotton tip is quickly absorbed and absorbed on the cotton plant. The new leaves, fruit branches and stems to be produced by the cotton plant are all contained in the cotton tip. If the cotton tip has no medicine, it will not be able to achieve the goal of getting smaller in the next three leaves and shortening in the next three internodes. So spray when there is a large leaf to cover the cotton tip, be sure to spray the liquid to the cotton tip from the side.

Third, because the seedling is suitable for the same plot, it is necessary to master more spraying of big seedlings, less spraying of small seedlings or no spraying of small seedlings.

Fourth, the test effect if the new tender leaves do not change 3 days after spraying, indicating that the dosage is small, you can spray again as appropriate; if the new tender leaves are dark and shiny and the wrinkles are obvious, it shows that it worked.

Fifth, fertile to increase the amount of fertile melons, vegetables, garlic and stubble fields, less medicine does not work, spray more suitable? The experiment can be done first. Mind do not be imprisoned, particularly fertile land, 1 mu of medicine 1 to 2 grams of medicine does not work. As long as the dosage is increased, there is no uncontrollable cotton field.

Sixth, mainly control the dosage of 0.3 kg / mu and 0.5 g / mu, and 10 / mu and 15 kg of water per mu at the seedling stage.

Seventh, the irregularity of seedlings should be controlled alone and single spray Jiean can prevent large seedlings and small seedlings from using the same amount of drugs. if mixed spraying of pesticides is added, chemical control must be given priority to, and many insects should not be sprayed, so as not to affect the growth of cotton plants.

8. After the start of chemical control, the pharmacodynamic period of Jiaoan should not be interrupted for 10 to 15 days. If the chemical control is not continued after the initial chemical control, the growth of cotton plants will rebound, and even the previous efforts of chemical control will be wasted. Therefore, after starting chemical control, the chemical control is carried out every 8 to 10 days, and the dosage increases gradually, and the interval date and dosage depend on the growth status and weather conditions of cotton plants.

Chemical control morning and evening different doses of chemical control start to use less drugs early, start too late and use more drugs appropriately.

10. According to the requirements of different density and high density, the plant should be controlled earlier and the chemical control should be larger; if the density is low, the requirement of plant height is not too strict, and the chemical control can be relaxed appropriately.

Chemical control do not forget to topdressing cotton plants after chemical control, the leaves become darker, but it does not mean that there is no lack of fertilizer. If you want to be topdressing, you must be topdressing. In the plots with uniform growth and low soil fertility, 1% urea can also be added during chemical control to control the seedlings and supplement nutrients, but do not add fertilizer in the cotton fields where the cotton seedlings are irregular, otherwise the big seedlings will be bigger.

12. Combined with the weather forecast, the best chemical control is before the rainfall, and it is easy to cause passive chemical control after the rainfall.

13. Heavy chemical control can be remedied in accordance with the above-mentioned methods of chemical control, generally there will not be the problem of excessive chemical control. There are often four situations in chemical control of overweight: first, the calculation of the dosage is wrong or the spray is not mastered; the second is to forecast rain, but there is no rain after spraying; the third is to spray with unknown ingredients, such as nutritional medicine containing regulators and shrinking safety; fourth, it is ineffective after chemical control, and then spray more. If the chemical control is heavy, 1% urea can be sprayed to alleviate it; when urea spraying is ineffective, "920" can be sprayed.