| Fall armyworm（FAW）Spodoptera frugiperda is a global agricultural pest.It invaded our country’s Yunnan Province in 2019,which has seriously threatened the safety of Chinese food production.In recent years,with the rapid development of plant protection unmanned aerial technology and the advancement of our country’s population aging and rural urbanization,plant protection unmanned aerial spray is increasingly becoming the primary operation method for pest control.At present,the technology of using plant protection unmanned aerial to prevent and control common diseases,pests and weeds in my country is mature,but there are still some gaps in the spraying technology of using plant protection unmanned aerial to control FAW.Therefore,this paper uses a plant protection unmanned aerial to study the effects of spray volume,droplet size,spray additives,and pesticides on the droplet deposition characteristics and the control efficacy of FAW.For the deposition characteristics of droplets,this paper studies the influence of different sampling methods,spray volume,droplet size,spray additives on droplet density,coverage,deposition,deposition uniformity and other factors.At the same time,laboratory experiments were conducted to study the surface tension of spray additives on the solution and the change law of contact angles of different spray additives on corn leaves.For the control efficacy of FAW,this paper uses the survey method of insect population base number and the investigation method of corn hazard index to study the effect of spraying volume,droplet size,and different pesticides and additives on the control of FAW.The experimental research results and conclusions are as follows:（1）With the increase of spray volume（7.5 L/ha,15.0 L/ha,22.5 L/ha,30.0 L/ha）,the droplet density and coverage gradually increase and have a good linear relationship.Different sampling methods have significant differences in droplet density and coverage（p<0.01）.In the control experiment of FAW,the control efficacy gradually increased with the increase of spray volume,but there was no significant difference in the control efficacy between the spray volume of 22.5 L/ha and the spray volume of 30.0 L/ha.In order to improve the efficiency of plant protection unmanned aerial when spraying in the field,it was recommended to use a spray volume of 22.5 L/ha.（2）With the increase of the droplet size（90μm,135μm,200μm,285μm,555μm）,the droplet density gradually decreased and there was a significant difference（p<0.01）.The droplet coverage decreases first and then increases with the increase of the droplet size,but there was no significant difference.In the control experiment of FAW,the effect of the droplet size on the control efficacy was different.When the size of the droplet was 135μm,the control efficacy of FAW was the best.（3）Spray additives have a significant effect on the surface tension of the solution,and Starguar4A spray additives have the greatest effect on the surface tension of the solution.The contact angle of the droplets on the corn leaves changed significantly after spraying additives were added,and the Ultimate spraying additives had better wetting and spreading properties.Different spray additives have different effects on droplet density,deposition amount,and DV0.5.Among them,Bei Datong spray additives have the largest increase rate.Different spray additives have no significant difference in the uniformity of droplet deposition.（4）Different pesticides have different control efficacy on FAW.Among them,Emamectin benzoate,Ethyl polypasteurin can achieve more than 95%of the control efficacy of FAW,which is better than the control efficacy of spraying Chlorantraniliprole with knapsack sprayer.Based on the above research results,we recommend that when plant protection unmanned aerial used in the field to control FAW,the spray volume of the plant protection unmanned aerial was 22.5 L/ha,and the droplet size was 135μm.In the spray process,it was preferred to use the spray additives of Beidatong.In the application period,try to choose the young age to spray the contact pesticides and it is recommended that the time interval between the first application and the second application was 10 days.At the same time,in order to avoid long-term use of a single pesticides to produce resistance to FAW,it was best to rotate and use different pesticides to control FAW during field application. |
