Wheat field weeds appear the first emergence peak at 15-20 days after sowing, which is also the largest emergence peak. Some weeds may also have a small emergence peak in March of the following year. Through a large number of experiments, there are three critical periods for weed control in wheat fields. 1. It is an important period for the prevention and control of wheat field weeds before wheat emergence. 2. Wheat seedling stage (mid-November and late November) is the best time to control weeds in wheat field. 3. The wheat returning green period (late February to mid-March) is a supplementary period for controlling weeds in wheat fields. According to the law of emergence of weeds in wheat field, and at the same time, according to the species of weeds and climatic conditions in wheat fields in our county, wheat seedling stage (mid-November and mid-November) is the best period to control weeds in wheat fields. First, the temperature is high, the drug absorption and conduction is fast, and the efficacy can be fully exerted, which can improve the weeding effect. Second, the weeds have been basically excavated, but the water and nutrients in the soil have not yet been consumed, and the wheat has not been affected; Third, small weeds, young weeds, poor drug resistance, and rapid death rate; Fourth, small wheat plants, small groups, large amounts of weeds, weeds, high mortality, complete weeding; five wheat at this time Strong resistance, it is generally not easy to cause injury, and it is safe for wheat. To sum up, the middle and late November is the best time for chemical and weed control in wheat fields in our county. This period should be based on grass conditions, temperature, select the appropriate herbicide species, timely application of pesticide control. Herbicides commonly used are: superstars, hummocks, 24D butyl ester, dimethyl tetrachlorinate salt, so that it Long and so on. In the middle or late November, there was no timely weeding and weeds occurred in severe wheat fields. They could be treated during the returning green period (from late February to mid-March), but the spraying period should not be too late to avoid causing damage to wheat. Irrespective of years before or after years of application, the amount of medication should be strictly controlled to prevent the occurrence of phytotoxicity. Endotracheal Tube,tube endotracheal,endotracheal tube holder,oral endotracheal tube,endotracheal tube price Anesthesia Medical Co., Ltd. , https://www.jssinoanesthesias.com