Effect of aerial application of adjuvants on pepper defoliant droplet deposition and efficacy of defoliation sprayed by unmanned aerial vehicles

Abstract

Defoliant spraying is an important aspect of the mechanized processing of pepper harvesting. Complete and uniform spraying of defoliant could improve the quality of defoliation and reduce the impurity content in processing pepper. In this study, we assessed the effect of aerial spraying of adjuvants on physicochemical properties of defoliant solution and droplet deposition when using an unmanned aerial vehicle (UAV) for defoliation spraying. The results showed that Puliwang was a better aerial spray adjuvant suitable for spraying defoliants for processing pepper using UAVs, with a higher defoliation rate and better droplet deposition. Although the YS-20 adjuvant had a higher droplet deposition amount (0.72 μg/cm2) in the middle layer, its performance was poor in droplet size, density, and coverage. The size and density of the droplets added with the Manniu were basically the same as the Puliwang, even the distribution uniformity was better (the CV of the upper canopy layer was only 33.6%), but the coverage rate was poor. In the treatment with AS-901N, there was no marked increase in droplet size, so evaporation and drift were not improved, eventually resulting in a lower defoliation rate. Puliwang had the highest comprehensive score, followed by AS-910N, YS-20, and Manniu.

Spray performance and control efficacy against pests in paddy rice by UAV‐based pesticide application: effects of atomization, UAV configuration and flight velocity

“…reported improved deposition and coverage from adding an adjuvant, especially with the LU12001 nozzle during rice's tillering and flowering stages. Liu et al 34 . also reported the suitability of adjuvant addition for defoliation spraying using UAVs, enhancing defoliant spray effectiveness and droplet deposition.…”

“…Similarly, Chen et al 13 reported improved deposition and coverage from adding an adjuvant, especially with the LU12001 nozzle during rice's tillering and flowering stages. Liu et al 34 also reported the suitability of adjuvant addition for defoliation spraying using UAVs, enhancing defoliant spray effectiveness and droplet deposition. Droplet penetration by UAV and EKS sprayers was assessed by comparing spray deposition percentages between the upper and lower layers of the rice canopy.…”

Impact of Operational Parameters on Droplet Distribution Using an Unmanned Aerial Vehicle in a Papaya Orchard

“…Although the results of this study were significant for the use of the UAV in the distribution of drops on papaya plants, the morphological architecture of papaya plants is different according to the stages of plant development. However, for applications using UAVs, the canopy structure of the crop plant directly impacts the settings of the operational parameters, as considered in [31,55,56] and recently in [26]. In this regard, further experimental studies are needed to elucidate new operational parameters, such as new application rates, operational flight speed and height, spray nozzles, and flight paths, in order to increase the application efficiency and effectiveness in pest and disease control in papaya crops.…”

Back pressure generated by downwash and crosswind on spatial atomization characteristics during UAV spraying: CFD analysis and verification

“…Under this condition, the breakage and further atomization of droplets will occur, 3,4 leading to variation in their size and distribution. Such a process changes the spatial atomization characteristics, which increases the potential risk of drift 5 so as to escalate pesticide loss 6,7 and compromise the efficacy of crop protection 8,9 . Therefore, it is of great significance to clarify the relation between the back pressure caused by airflow and spatial atomization characteristics to optimize practical spray operations.…”