| In recent years,the occurrence area of insect pests in cotton fields in Maigaiti reclamation area has continuously expanded due to multiple factors such as climate and environment changes,changes in planting methods,industrial restructuring,and the increase of insect sources from other places.For the same reasons,the occurrence of large-scale outbreaks of harmful organisms has increased significantly as well.The loss of cotton output in Maigaiti reclamation area has increased year by year,seriously affecting the high-quality and efficient production of cotton.Pesticide application technology is directly related to the efficiency of cotton pest control.At present,the plant protection machineries in the cotton fields of Maigaiti land reclamation area are primarily hang knapsack power sprayers,and suspension and traction type sprayers.They are unable to meet the requirements of modern agricultural development because they are limited by the conditions of water use,labor shortage,and operation efficiency and low pesticide utilization rate.Thus,they fail to achieve the effect of universal pest control in a short time and cause a major problem to cotton production.Unmanned aerial vehicles(UAV)for agricultural plant protection have been widely used in pest control of cotton,wheat and rice in recent years due to their advantages of safety,high efficiency,environmental protection.They also save time,labor,and cost.The application of UAV has gradually become a new application method for pest control in Xinjiang cotton fields.Although using plant protection type UAV to spray at a low altitude and a low volume has many advantages,the technical system is not perfect.For different models of plant protection type UAV,different operation parameters need to be provided as theoretical references for preventing and controlling pests in different crops.In this paper,we use P20 plant protection UAV as the research object.Through the combination of systematic investigation and comprehensive survey,the occurrence regularity of main pests in cotton fields in Maigaiti reclamation area is studied.To provide theoretical basis for the popularization and application of P20 UAV in cotton fields in southern Xinjiang,the operation parameters of P20 UAV for controlling three pests in different growth periods of cotton are optimized.The control effect is also evaluated.The main research results of this paper are as follows:1.Occurrence regularity of main pests in cotton field in Maigaiti reclamation areaAccording to the investigation,the common pests in cotton fields in Maigaiti reclamation area are cotton thrips,aphids,cotton spider mites,cotton bollworm and cotton bug.Among all the common pests,the pests with relatively larger area and higher degree of damage are cotton thrips,cotton aphids and cotton spider mites.The regularity of occurrence is as follows: Cotton thrips moved into cotton fields in mid-April and reached its peak in early June,causing serious damage to cotton at seedling stage;Cotton aphids began to migrate into cotton fields from late April to early May and reached the peak of damage from late June to early July.Cotton spider mites began to immigrate in the first half of June and reached the peak of damage from the beginning of July to the middle of July.If the control is not timely,the population density will increase rapidly in hot and dry weather.2.Measurement of effective spray amplitude of P20 UAVEvaluation of effective spraying width is the premise of accurate operation of UAV.It is important to reduce the rate of heavy spray leakage and improve spray quality.The droplet deposition density method was used to determine the spraying operation of P20 UAV at different heights and flight speeds.It was found that the droplet deposition amount on the droplet test card was different.The droplet deposition amount at the sampling point under the central route was the largest,and that on both sides of the route gradually decreased.P20 UAV spray amplitude is closely related to operation height and flight speed.when the speed is constant,and the height is1.5m ~ 2.5m,the higher the height,the wider the spraying amplitude.When the altitude is constant,and the flight speed is between 4m/s and 6m/s,the faster the flight speed,the wider the spraying width.The effective spray amplitude is 3.1m~3.6m when the working height is 1.5m,3.2m ~ 4m when the working height is 2m,and 3.5m~4.5m when the working height is 2.5m.The results provide the basis for further optimizing the working parameters3.Optimization of parameters and evaluation of control effectiveness of P20 UAV in seedling stage for the control of Thrips tabaci L.One day after application,the flight speed and total flow rate of plant protection UAV had a significant effect on the control efficacy of cotton thrips.When the height was 1.5 m,the speed was 4 m/s,and the total flow rate was 1.6 L/min,the maximum control effect was 61.3%;3 days after application,flight speed had a significant effect on the control effect.When the combination of operation parameters was 1.5m-4m/s-1.6L/min,the control effect would reach 90.5%,and the ideal control effect could be achieved.Under the operating parameters,the plant protection UAV saveed 25% of the pesticide and 97% of the water.The operation efficiency was about 5 times better than the mechanical traction type sprayer.After comprehensive analysis,it is suggested that the UAV operating parameters for controlling hrips tabaci L in seedling stage should be 2 m in height,4 m/s in flight speed and 1.4 L/min in spraying amount.At the same time,the agents with good contact killing effect and strong suction should be selected to control hrips tabaci L.4.Optimization of parameters and evaluation of control effectiveness of P20 UAV in buding stage for control of aphis gossypii GloverThe results of the P20 UAV spraying operation in the cotton field of the bud stage indicate that the effect of fog droplets on cotton canopy subsidence is quite different from that of cotton canopy subsidence,presenting the law of the middle > upper > lower.The height of operation is the most important factor affecting the deposition of fog droplets in the upper canopy of cotton.The optimal combination is a working height of 1.5m,a flying speed of 4m/s,and a total spraying flow of 1.4L/min.The most important influence on the density of droplets in the middle of the cotton canopy is the flight speed.The optimal combination is a working height of 2m,a flying speed of4m/s and a total spraying flow of 1.6L/min.The lower droplet deposition density is most affected by the working height.The optimal combination is the working height of 1.5m,the flying speed of4m/s,and the total spraying flow of 1.6L/min.Control effect of different applicating machines on cotton aphid at bud stage shows that 7 days after application,when UAV height is 1.5m,speed is 4m/s,total spraying flow is 1.4L/min and height is 2m,speed is 5m/s,and total spraying flow is 1.4L/min,the control effect is more than95%.There was no significant difference in the efficacy of spraying with mechanical traction sprayer.They were both able to control pest occurrence in time.In general,the recommended operating parameters for controlling cotton aphid in bud stage were operating height 2 m,flying speed 5 m/s and total spraying flow 1.4 L/min.5.Optimization of parameters and evaluation of control effectiveness of P20 UAV in bolling stage for control of tetranychus cinnabarinus L.The results of the P20 plant protection drone spraying operation in the cotton field of the bolling stage indicate that the deposition density of fog droplets in Cotton Canopy has a rule of upper layer > middle layer > lower layer.Flight speed is the most important factor affecting the deposition density of cotton canopy.The flight speed of operation is the most important factor affecting the deposition of fog droplets in the upper canopy of cotton.The optimal combination is a working height of 2m,a flying speed of 4m/s,and a total spraying flow of 1.6L/min.The height of operation has the greatest impact on the middle and lower parts.The optimal combination is a working height of 1.5m,a flying speed of 4m/s and a total spraying flow of 1.4L/min,or the working height of 1.5m,the flying speed of 4m/s,and the total spraying flow of 1.6L/min.Control effect of different applicating machines on tetranychus cinnabarinus L at bolling stage show that after 3 days of application,the maximum control effect of UAV reached 94.6%.There was no significant difference in the efficacy of spraying compared with mechanical traction sprayer.In general,The recommended Operation parameters of Use P20 UAV to control tetranychus cinnabarinus L in boll stage are as follows: operating altitude 1.5 m,flying speed 4m/s,total spraying flow 1.6 L/min.Operating parameters for controlling cotton aphid in bud stage were operating height 2 m,flying speed 5 m/s and total spraying flow 1.4 L/min.It can solve the problems such as damaging cotton branches and leaves in the process of pest control in the middle and late growth stage of cotton,and missing the best prevention and control period,etc. |
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