Experiment on prevention and control of rice planthopper by ultrasonic pneumatic spray

Abstract: In the current, ultrasonic atomization technology is becoming the key technology of ultra-low volume spray technology in facility agriculture. In order to systemically research the factors affecting the control effect of ultrasonic pneumatic spray on rice planthopper, in this study, the ultrasonic pneumatic spray test platform for rice planthopper was built. This test platform simulated the growth environment of rice planthopper by controlling the temperature, air flow and soil environment. The temperature of the test platform was adjusted by the heater through the PID (proportion, integral, derivative) control system. The air flow was controlled by the electric fan which was placed on the side. The soil was taken directly from the experimental plot in the Yangzhou University. The effects of different operating parameters such as liquid concentration, spray height, moving speed and strength value on the performance, wide width of spray and droplet size of ultrasonic aerosol were studied, and the control effect of ultrasonic aerodynamic spraying on rice planthopper was tested and verified. The biological dye Ponceau-G, which was used as tracer, and distilled water were mixed to be the hydrojet that had the same density and viscosity as pesticide. This kind of hydrojet can leave a trace that is not easy to spread on the qualitative filter paper. The performance and wide width of spray could be qualitatively observed on filter paper. The spray droplets were collected by the white oil which was used as the collection liquid. The droplet size was obtained by 500 times microscope and measuring micro ruler. The rice planthopper and rice seedlings from the Ecological Laboratory of Yangzhou University were placed in the test platform, and using the same configuration of imidacloprid, the control effects of ordinary spray and ultrasonic pneumatic spray on rice planthopper were compared. The experimental results show that when the nozzle moves at a speed of 160 mm/s and a flow rate of 5.5 mL/min, the atomization rate is the highest and the atomization effect is better than others. When the flow rate is 5.5 mL/min, the pesticide utilization rate is the highest. The average values of particle size are basically the same at different pneumatic values, all of which are about 25 μm, and when the air pressure is 20 kPa, the width of atomization reaches 240 mm. Because the particle size of the aerosol spray droplets is very small, the wind speed has a great influence on the droplet trajectory, which can ensure the normal operation of the spray in the greenhouse by increasing the air force value. The adhesion effect of droplets on the blade will be affected by spray flow, droplet diameter, wind speed and blade tilt angle. In comparison with ordinary spray, the pesticide utilization rate of ultrasonic pneumatic spray is increased by 35%-45%, and the control effect on rice planthopper is increased by 10%-36%. The experimental results are of guiding significance and practical value to improve the status quo of relatively backward equipment and technology, and to improve the mechanized control technology of chemical pesticide.