Study On Dose Distribution And Regulation Of Imidacloprid Control Release Granules In Wheat Aphid Control

In the main growing areas of winter wheat of China,aphid control is mainly achieved by the foliar spray.Usually,wheat aphids can harm wheat throughout its growth period,and the aphids concentrate on the back of wheat leaves or on the stalks to suck the sap.In the process of foliar spray application,pesticide drops would evaporate,drift,bounce,and that is sometimes difficult to deposit them on the stems or the back of leaves.It was not only result in the low utilization rate of pesticides,but also poses the risk of exposure to non-target organisms.Seed coating technology has been extensively used in agriculture,but its impact on farmland birds and the growth or development of crop seedlings has gradually attracted people’s attention.Due to the low utilization rate of pesticides and environmental pollution caused by using of pesticides in spraying or seed coating,a new pesticide formulation was prepared based on the occurrence rules of aphids and their harmful characteristics on crops in order to use pesticides efficiently and scientifically.This topic was prepared by two kinds of imidacloprid control-release granules,indoor experiment and the field experiment carried out respectively to comprehensively evaluate the release property of the two kinds of imidacloprid control-release granules performance.The dose distribution in the different part of wheat,control effect on wheat aphid,the residues in edible parts of wheat and effect on wheat yield were studied.The experimental results showed that the two kinds of control-release granules had good control-release properties,and the release property of 2% imidacloprid control-release granules was better than 0.2% imidacloprid(pesticide fertilizer)control-release granules.0.2% imidacloprid(pesticide fertilizer)control-release granule contains a large amount of chemical fertilizer,which is easy to absorb water and swelling,and is conducive to the release of effective components of control-release granule in the releasing medium.Therefore,the release performance of 2% imidacloprid control-release granule is better than that of imidacloprid control-release granule.In order to compare root application with foliar spraying,imidacloprid wettable powder was applied to wheat to obtain the eluent rate of imidacloprid on wheat leaves.Within 21 days after application,the eluent rate of imidacloprid on wheat leaves was 50.8-71.3%,indicating that most of the pesticides on wheat leaves were easy to be washed away by water.After 21 days of application,the concentration of imidacloprid on the wheat plant was regarded as the effective amount of deposition,and the concentration of imidacloprid on the wheat plant was 0.18mg/kg,only 8% of the effective amount of deposition.Therefore,after foliar spraying,most imidacloprid could not be absorbed directly by wheat leaves,but was lost to the environment or degraded.In the field experiment,two kinds of imidacloprid control-release granules and wheat seeds were seeded into the soil at the same time,and the concentrations of imidacloprid in the soil,wheat roots and plants were detected by taking samples at different growing stages of wheat.After the wheat turned green,the soil temperature and humidity rose rapidly,and the imidacloprid concentration in the soil reached the maximum value.Then,the imidacloprid concentration in the soil gradually decreased over time.The concentration of imidacloprid in the root of wheat was the highest in spring,and decreased with the increase of wheat biomass.The absorption of fertilizer by wheat root system increased rapidly from the turning green stage,so the concentration of imidacloprid was higher in the turning green stage and the jointing stage.With the increase of biomass and metabolism,the concentration of imidacloprid in wheat plant decreased gradually.The absorption of fertilizer by wheat root system increased rapidly from the turning green stage,so the concentration of imidacloprid was higher in the green stage and the jointing stage.The growth cycle of winter wheat is long,and wheat aphid generally begins to breed after the wheat turns green,and the imidacloprid concentration was higher in the wheat turning green period and the jointing stage,which was beneficial to the control of wheat aphid.With the increase of biomass and metabolism of wheat,the concentration of imidacloprid in wheat plant decreased gradually.In summary,two imidacloprid control-release granules can control aphids,ensure wheat yield and reduce the safety of edible sites throughout wheat growth.Compared with foliar sprays,sowing in soil was more targeted,reducing the risk of exposure to bees and other pollinators,and thus improving pesticide utilization and safety.Imidacloprid control-release granules are used to control wheat aphids during the whole growth period of winter wheat,which is one of the effective measures to improve the utilization rate of pesticide,guarantee the yield and reduce the environmental risk,and provides a theoretical basis for the optimization and scientific use of pesticide dosage forms.