Establishment of precise pesticide spraying calculation model for orchard based on the interfacial characteristics of apple leaves and pesticide solution

In order to ensure accurate spraying of pesticides and reduce the loss of pesticides in fruit trees, a calculation model of precise pesticide spraying quantity in orchards was established. The model included the canopy parameters, interface properties of the fruit tree, and the pesticide destination in the orchard, which could be used to guide the modes of spraying for different plant protection machinery under different planting patterns in the orchard. By selecting 'Fushi' apple leaves of different phenological periods as research objects, the leaf surface free energy and canopy parameters were tested. The relationship between liquid surface tension and maximum liquid holdup was established for apple leaves. The maximum pesticide loading of the whole tree was calculated based on maximum liquid holdup and canopy parameters. The calculation model of precise pesticide spraying quantity was established, combined with the pesticide destination in the orchard. The application of two kinds of spraying machines, stretcher plunger pump sprayer in the low-density planting orchard and self-propelled axial flow sprayer in the close planting orchard, were taken as examples, and the practicability of the model was verified. The results showed that the use of a stretcher plunger pump sprayer in the early stage in the low-density planting orchard could save 37.40% of liquid compared with the original, and 18.75% of liquid could be saved in the later stage. The use of a self-propelled axial flow sprayer in the late stage of the close planting orchard can save 28% of the liquid. There was no significant difference between the control efficacy and the dosage of conventional liquid medicine. This model combined the interface properties of apple leaves with the application equipment could not only calculate accurately the spraying amount of pesticide according to the actual situation of the orchard, but also evaluate the applicability of pesticide liquid at a certain period. The mode could adjust the parameters of the pesticide liquid and spray machine according to the actual situation, so as to achieve the purpose of precise pesticide application.