UAV-Based Precision Spraying Enhances Pest Control, Nutrient Uptake, and Spray Efficiency in High-Density Mango Orchards

Abstract

Mango (Mangifera indica L.) is a major tropical fruit crop that suffers yield losses from nutrient deficiencies, insect pests, and fungal diseases, with conventional spraying methods such as tractor-mounted or manual sprayers often requiring excessive spray volumes, leading to poor canopy penetration, chemical wastage, operator health risks, and environmental contamination. Recent advances in Unmanned Aerial Vehicles (UAVs) have enabled site-specific spraying, offering precision application, reduced chemical use, and improved safety, though research in mango orchards remains limited compared to crops like citrus, vineyards, and rice. This proof-of-concept study conducted in high-density Alphonso mango orchards in Tamil Nadu, India, from September 2023 to March 2024, compared UAV spraying at 1 L/tree (T1), 2 L/tree (T2), and 3 L/tree (T3) with tractor spraying at 15 L/tree (T4). UAV-mounted multispectral sensors captured canopy spectral indices, while bio-efficacy was validated using chlorophyll index (SPAD), pest incidence, and NDVI analysis. Results showed that T2 (2 L/tree UAV spraying) achieved pest and disease suppression comparable to tractor spraying, while reducing spray volume by 70% and drift by 40%. UAV spraying also enhanced chlorophyll index and canopy reflectance, indicating improved nutrient absorption. Overall, findings demonstrate that UAV spraying is technically feasible and economically viable for mango orchards, reducing agrochemical inputs while maintaining effective pest and disease control, and highlight UAV spraying as a sustainable precision agriculture strategy with strong potential to transform orchard management in tropical fruit systems.