Interactions between spray drift and sprayer travel speed in two different apple orchard training systems

Trials were carried out in apple orchards of two different training systems to assess the relationship between spray drift and parameters of spraying with an emphasis on the sprayer’s travel speed when applying different solutions, such as pesticides or fertilizers, onto the apple trees. The assessments were based on the following factors: per cent of spay drift, two sprayers (axial- and radial-fan sprayer), two training systems (super spindle and modified slender spindle), spray droplet size (fine or coarse droplets) and the sprayer’s travel speed (5 vs. 10 km h^-1). The studies were conducted in the spring and summer seasons under similar external weather conditions to test any seasonal effects that might occur. In this paper, all tested factors and interactions were found to have a significant effect on the spray drift during spray application. For instance, the increase in sprayer speed reduced the spray drift percentage. Other factors, such as sprayer type (axial fan and radial fan) and tree training system, had an impact on spray drift as well.