Study On Pesticide Droplet Size And Deposition Density With The Control Effect Of Wheat Aphids

Wheat ahpids are the main pests in wheat in china, which can serious reduce wheat yield and quality. The main control measure of wheat aphids on the production was using of plant protection machinery to spray chemical pesticide. In recent years, plant protection equipment developed rapidly, especially the aviation plant protection machinery. But the pesticide application technology was still on the initial stage in our country, the unreasonable selection of spray volume, droplets size, pesticide type all can result in the low pesticide efficiency, high pesticide drift and poor control effects.In this paper, used wheat aphids as a target insect, a detailed study of the relationship between droplet size, density, concentration of five different pesticides and control effect of wheat aphids was described. In the field experiment, we used six kinds of plant protection equipment, studyed the relationship of different spraying methods with the control effect of wheat aphids. Allura red was used as tracer in the field experiment, but the feasibility was not fully certified. In this paper, we study the effect of adding allura red in the pesticide and water on the viscosity, surface tension, density and droplet spectrum. After that, we test the effect on deposition amount of imidacloprid with adding allura red by ultra-high performance liquid chromatography(UPLC). Conclusions are as follows:(1)It is feasible to use allura red as deposition tracer. There was no significant effect on the viscosity, surface tension, density and droplet spectrum with adding allura red into imidacloprid solution and water. In the laboratory, we adding allura red into the imidacloprid solution and then simulate the field trial to spray and elution. The test result by ultra-high performance liquid chromatography(UPLC) showed that adding allura red had no significant effects on the deposition amount of imidacloprid at different concentrations.(2)In the laboratory, we used three different spray tower(Potter tower, Centrifugal rotary atomization system and ASS-3 spray tower) sprayed three different size(43μm,153μm,274μm) of droplets to study the relationship between droplets density, concentration of imidacloprid, thiamethoxam, lambda-cyhalothrin, abamectin, sulfoxaflor and the mortality of wheat aphid. In general, when the concentration was low(0.02 ~ 0.2g / L), linear relationship fiteed between the deposition density of droplets and the mortality of wheat aphid; when the concentration was high(0.5 ~ 5g / L), logarithmic relationship fiteed between the deposition density of droplets and the mortality of wheat aphid; The biocide radius and 50% mortality of wheat aphids(LN50) were effected by the size, concentration and density of the droplets. The biocide radius and biocide area increased as the size, concentration and the density of droplets increased. The result of 50% mortality of wheat aphids(LN50) was in contrast.The biocide radius of high concentration of lagre droplets was large and LN50 was lower. When the volume median diameter of imidacloprid droplets were 274 μm and the concentration was 5g/L, the 50% mortality of wheat aphids(LN50) was only 3.06 droplets cm-2, which was significant lower than the conventional spray. The results proved the feasibility of aviation low volume and high concentration spraying. To achieve the same LN50, small droplets(43μm)need fewer spray rate than biger droplets(153μm, 274μm) by analysized the different size of droplets.(3)The control effect of wheat aphids by different plant protection equipment spraying were effected by the size, concentration, density, uniformity and penetration of droplets. Boom sprayer which mounted TEEJET 110-04 has the best spray uniformity and penetration. The control effect on wheat aphids was 90.7%. The droplets of the mist sprayer was very fine but not uniform, and the control effect was 83.0%. The spray uniformity of knapsack manual sprayer and knapsack Electric Sprayer were significant effected by manipulator. The penetration and uniformity of droplets are common, and the control effect were 83.9% and 85.8%. Multi-roters UAV(mounted rotary centrifugal atomization nozzle) and Single-roters UAV(mounted TEEJET 110-02 nozzle) sprayed high concentration and small pesticide droplets. The uniformity of droplets was effect by manipulator and the control effect were 70.9% and 78.4%.According to the fitting equation of the laboratory test, we analysed the result of the field test finding that the mortality of wheat ahpids by spraying different concentration、size and deposition density of imidacloprid in the field was agreed well with the laboratory test.