Performance matching of common pesticides in banana plantations on the surface of banana leaves at different growth stages

Feasibility of Genipin to Evaluate Chitosan Rainfastness for Biopesticide Applications

Chitosan's effectiveness as an antimicrobial coating for biocontrol depends on its resistance to rain. Unfortunately, to the best of our knowledge, there is currently no satisfactory method for assessing this resistance, which means that field tests have to be carried out to evaluate it in situ, which are difficult to implement and therefore unsuitable for optimizing formulations. This article explores the use of genipin to detect residual chitosan on surfaces after simulated rain, using fluorescence microscopy. A first study on real vine leaves using MacroFluo microscopy was carried out but showed limitations for the intended application, notably due to the requirement for high chitosan concentrations to achieve detectable signals. A semi-quantitative method based on confocal laser scanning microscopy was then developed on model leaves, as real leaves were unsuitable due to their autofluorescence. Among the tested models, Parafilm® proved to be the most effective, showing sufficient fluorescence after reaction with genipin, even at low chitosan concentrations. For the first time, a method that does not require chromophore grafting onto chitosan has been proposed, allowing for the comparison of chitosan solution rainfastness under laboratory conditions. As an application, the effect of the counter ion on chitosan's rain resistance was evaluated.

Effect of operational parameters on droplet deposition characteristics using an unmanned aerial vehicle for banana canopy

In recent years, as an important part of precision agricultural aviation, the plant protection unmanned aerial vehicle (UAV) has been widely studied and applied worldwide, especially in East Asia. Banana, as a typical large broad-leaved crop, has high requirements for pests and diseases control. The mechanization degree of plant protection management in banana orchard is low. Therefore, our study focuses on the effects of different flight heights (3-5 m) and droplet sizes (50-150 μm) of plant protection UAV on the droplet deposition distribution characteristics of banana canopy. And the droplet deposition distribution in banana canopy and spraying drift of plant protection UAV and ground air-assisted sprayer were compared. The results showed that droplet size was the main factor affecting droplet deposition density, coverage, uniformity and penetration on both sides of banana canopy leaves. The droplet deposition density and coverage on the adaxial side of leaves were mostly significantly larger than that on the abaxial side. The flight height of 4 m and the droplet size of 100 μm could make the adaxial side of banana canopy leaves have higher droplet deposition density (63.77 droplets per square cm) and coverage (12.75%), and can make the droplets effectively deposit on the abaxial side of banana canopy leaves, with droplet deposition density of 17.46 droplets per square cm and coverage of 1.24%. Choosing an appropriate flight height and a droplet size could improve the droplet deposition uniformity on both sides of banana canopy leaves, but the improvement was not significant. Moreover, at a same operational parameter combination, it was difficult to achieve the best droplet deposition density, coverage, uniformity and penetration at the same time. In addition, appropriately increasing the flight height and droplet size could help to improve the droplet deposition penetration on the adaxial side of banana canopy leaves, but there were few significant improvements. Compared with the plant protection UAV, the ground air-assisted sprayer had higher droplet deposition density and coverage on the abaxial side of banana canopy leaves, but had smaller droplet deposition coverage on the adaxial side. The droplet deposition density and coverage on the abaxial side of banana canopy leaves were obviously larger than the adaxial side during the spraying of ground air-assisted sprayer. The droplet drift distance of the ground air-assisted sprayer was farther than the plant protection UAV. The test results of this study can provide practical and data support for the UAV aerial application in banana orchard, and provide a valuable reference for the implementation of air-ground cooperation spraying strategy in banana orchard, which is of great significance to promote sustainable and intelligent phytoprotection of banana orchard.

Regulating the dynamic wetting behavior of pesticide on banana leaves at different growth stages with surfactants

BACKGROUND

Pesticide spraying constitutes an essential component of the production and management regimen within banana orchards, extending throughout the entire growth cycle of the banana plants. Exploring the intricate interplay between surfactants, pesticide formulations, and the evolving surface properties of banana leaves throughout their growth stages is critical to the enhancement of pesticide application methods and the elevation of agricultural productivity.

RESULTS

Through investigating the regulatory impact of surfactants on the physicochemical properties of medicinal solutions, this study elucidates the interaction mechanism between the physicochemical properties of pesticides and the surface characteristics of banana leaves. The findings reveal that the energy dissipation rate of pesticide droplets exhibits a natural exponential rise in correlation with the increase in both the We number and the concentration of surfactant present. Comparatively, the adaxial surface of banana leaves demonstrates superior spreading and adhesion properties for droplets than the abaxial surface. Specifically, droplets containing the anionic surfactant sodium dodecyl sulfate on the adaxial surface of banana leaves are found to spread well with a reduced retraction effect. Conversely, the application of the non-ionic surfactant fatty acid polyoxyethylene ether (AEO-3) on the abaxial surface of banana leaves is more beneficial for the wetting and retention of droplets. As banana leaves grow, there is a noted decline in the spreading and retraction properties of droplets. However, droplets have a higher propensity to wet and adhere to the surfaces of mature banana leaves.

CONCLUSION

To bolster the adherence of pesticide droplets to leaf surfaces, it is imperative to ensure they possess superior spreading properties and a controlled retraction pace. This facilitates an extended period of contact and enhanced stability, thereby optimizing the spray's deposition efficacy. © 2024 Society of Chemical Industry.

Surface morphology and microstructure of Bauhinia variegata L. flowers and leaves

The main purpose of this research is to characterize the wettability and microstructure of Bauhinia variegata L. flowers and leaves, aiming to provide a biological template for the preparation of hydrophobic surfaces. The contact angle test results show that the surfaces of flowers and leaves are hydrophobic, and the contact angle of the adaxial side and abaxial side of the leaves is highly significant difference, which is mainly affected by the topological morphology of the surface microstructure. The topological structure of flower and leaf surface morphology was revealed by scanning electron microscopy (SEM) and super-depth of field three-dimensional microscope. The results showed that the cell structure of flower surface array was the main factor leading to the hydrophobicity of flowers. The snowflake-like structure on the leaf surface is the main factor leading to hydrophobicity of leaves, and the burr structure of the micro-nano dual-level structure unique to the abaxial side of the leaf further enhances the hydrophobicity of the abaxial side, and the contact angle increases, resulting in a highly significant difference in wettability between the adaxial side and abaxial side. This provides an important biological template and reference value for the preparation of biomimetic materials.