Study On The Control Of Diseases And Insect Pests Of Arrowhead In Paddy Field Based On The Application Technology Of Plant Protection UAV

China’s paddy field agricultural economy and culture are developed,but the supporting paddy field plant protection facilities and equipment can not meet the current development trend of intelligent,refined,green and efficient agriculture.Traditional paddy field pest control is still mainly based on manual sprayer and stretcher sprayer,with low technical content and low utilization rate of pesticides.Large self propelled or suspended sprayers are large and difficult to meet the needs of paddy field operation.The development of aviation plant protection technology provides a new way to improve the current difficulties of paddy field application.The UAV technology of plant protection can achieve cross terrain and high efficiency plant protection,reduce the harm of pesticides to the environment and operators,and reduce unnecessary pesticide waste.In this project,we carry out the research on the prevention and control of diseases and insect pests in paddy field based on the application technology of plant protection UAV.Taking the paddy field crop arrowhead as an example,we use UAV to effectively prevent and control the diseases and insect pests of Cigu,establish the spatiotemporal distribution model of diseases and insect pests,simulate the low-altitude application process of plant protection UAV,simulate and calculate the movement track of fog droplets in the rotor wind field,and optimize the application parameters of plant protection UAV Finally,the reliable and efficient control of diseases and insect pests of arrowhead was realized.First of all,by investigating the diseases and insect pests of arrowhead in paddy field,we selected the aphid of arrowhead as the control object,and carried out the research on the spatial and temporal distribution characteristics of the aphid on arrowhead plants.The entomological analysis was carried out on the survey data of 5,6,7 and 8 months,and the reason of aphid population aggregation was determined by regression equation.According to the time change analysis,The outbreak of the aphid of arrowhead mainly occurred in early July and early September,the reasons for the changes in the number of outbreaks and aggregations may be related to the climatic conditions,including temperature conditions and humidity regulation.According to the analysis of spatial changes,aphids distribute on the back of arrowhead leaves about one-third of the total amount,petioles account for two-thirds of the total amount,and there is almost no leaf surface.Aphid individuals are attracted to each other and have density dependence.The higher the density is,the greater the degree of pest aggregation is.At the same time,the Iwao sequential sampling model was used to get the control model of the aphid of arrowhead,and the relevant control strategies were formulated to provide scientific reference for the control of the aphid of arrowhead.According to the requirements of low dose directional pesticide application and the environmental conditions of paddy fields,the plant protection UAV low altitude and low dosage technology is applied to build indoor multifunctional spray plant for plant protection,and an ultra-low volume atomizing sprinkler is selected and designed.The flow field distribution of UAV rotor under different height,speed and speed at different speeds were simulated by Fluent numerical calculation.The results show that the flow field of the UAV rotor is convergent,contracting and pressing down,which is very beneficial to the deposition of the droplets;When the hovering height is changed,the UAV wind field produces lateral air flow,forming eddy current,and the wind field distribution changes with the increase of the height;When the inflow velocity is changed,eddy current is generated at the upstream of the UAV,and the eddy current position does not increase with the increase of the velocity.At the same time,the flow field under the rotor has a strong resistance to the incoming flow;In addition,the follow-up UAV field test verifies that the test results of droplet size distribution have a high correlation with the simulation results,which shows that the simulation can be used as a reasonable prediction method before the test.By comparing the 7-day decline rate of the two application methods in the experiment of disease and insect control of arrowhead,the decline rate of manual application is 85.67%,while that of UAV application is 90.14%and 91.25%,which is significantly higher,and the application efficiency is 20-30 times higher,so the UAV application method has more significant advantages.