Quantifying ash tree health using drone: Comparison of aerial and ground rating for emerald ash borer infestation

Emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), is an invasive wood-boring beetle responsible for widespread mortality of ash trees (Fraxinus spp.) across North America. Accurately quantifying ash tree health is critical for early detection, monitoring, and management in infested forests. This study evaluates the effectiveness of drone-based assessments by comparing ash tree health ratings derived from aerial imagery with traditional ground-based evaluations for emerald ash borer damage. Field data collection was conducted in July 2024 within the forested sites in Allegheny National Forest, Pennsylvania, where individual ash trees were identified and rated on a health scale from 1 (healthy) to 5 (severely damaged) based on visual canopy condition from ground. Subsequently, high-resolution aerial imagery was collected using a drone for the same area. Using ImageJ, pixel values were extracted from the canopy area of each georeferenced tree to assign aerial-based health scores. The comparison between ground and aerial ratings showed that aerial assessments were more consistent in differentiation between different health classes. These findings suggest that drone-based imagery, when combined with image analysis tools, can enhance the accuracy and efficiency of forest health assessments. The use of drone imagery for ash tree health rating shows strong potential for improving forest health monitoring and supporting timely pest management decisions.