Quality of Fungicide Application by a Remotely Piloted Aircraft for Sigatoka spp. Mitigation in a Banana Crop

Fungicide spraying by remotely piloted aircrafts (RPA) in banana farming is a promising alternative, but the relationship among operating parameters, application quality and biological effectiveness in disease control such as Sigatoka spp. is still poorly understood. The aim of this study was to assess the influence of different application rates and droplet sizes on spraying quality and Sigatoka mitigation in banana plants of the ‘Prata’ cultivar. A field experiment was conducted using an RPA, four rates of application (8, 10, 12 and 14 L ha−1) and three classes of droplet sizes selected on the RPA radio control (180, 240 and 300 μm). The application parameters significantly influenced the coverage and drop deposition. However, under the evaluated experimental conditions, no significant monotonic association was detected between these spray quality indicators and disease control efficacy, as assessed by the Stover Index. Lower rates of application (8 L ha−1) showed comparable disease control to higher rates. The results suggest that the relationship between quantitative deposition and biological efficacy was not directly proportional under the conditions evaluated, and a biological control threshold can be reached even with lower quantitative deposition, making operating efficiency optimization a viable strategy.