Safe use of long residual herbicides

Long residual herbicides are herbicides that remain in the soil for more than one year after some herbicides are used, which are easy to cause different degrees of drug damage to sensitive crops. Nowadays, on the one hand, the herbicidal activity of herbicides is getting stronger and stronger, and the dosage of herbicides is decreasing; on the other hand, crops are more and more sensitive to them. In particular, sulfonylurea herbicides, although the herbicidal activity is strong, the dosage is very small, but there are some problems in safety. In the production practice, the phenomenon of drug damage to the next crop caused by the application of long residual herbicides occurs from time to time, resulting in undue losses to production. For example, the long residual herbicides which are mainly composed of metformin, chlorosulfuron, aminobenzenesulfuron and so on, often cause yellowing, dwarfing and other drug damage symptoms in the growing period of rice. Therefore, attention must be paid to the damage of future crops of this kind of herbicides. First, different herbicides should be selected according to the characteristics of different soils, types of microorganisms, climate and irrigation conditions. According to the data, Lvhuanglong, Douhuanglong and Dihuanglong are degraded mainly by hydrolysis in soil. In the case of alkaline soil in the field, less rainfall in the same year, soil drought and so on, their residual period in the soil is often prolonged, and the subsequent crops are vulnerable; on the contrary, the residual period is shortened in acidic soil, soil moist or irrigated farmland, and the subsequent crops are relatively safe. Second, before planting the following crops, we should know whether the herbicides applied in the previous crops are harmful to the following crops. If herbicides containing chlorhexidine and metformin were applied in the previous crop, corn, soybean, cotton, peanut and other crops could not be planted in the subsequent crop, nor could they be used as seedling fields. In recent years, the use of benzoflavone (also known as superstar, broad-leaf net) in some places has caused varying degrees of drug damage to the next crop of peanuts, resulting in difficulties in emergence, slow growth and reduced yield of peanuts. Third, improve the application method and reduce the soil residue. First, the dosage should be accurate, spray evenly, do not leak spray, do not re-spray. If the herbicides containing chlorsulfuron are applied year after year, it will cause drug damage not only to the following crops, but also to the crops in the current season. Second, the period of use should be flexible. It can be treated with soil before sowing and before seedling, and can also be sprayed after seedling. At present, early post-seedling spray should be used in Pusht, Guangmianling and atrazine in order to reduce the dosage and residue. When used after emergence, it is recommended to add auxiliaries or synergists to improve efficacy and reduce drug dosage. The third is rational application of medicine. The mixture of chloruron and 2pyrone 4-butyl ester can reduce the dosage of chloruron by 50%. Pusht soil treatment can be mixed with trifluralin, Acetochlor, alachlor, Seikejin and so on. Banded spraying with Pushter and Guangmianling can reduce the dosage by more than 30%.