Evaluating warm‐season turfgrass: Multispectral and red–green–blue index comparison

Abstract Across the United States and much of the globe, turfgrass is managed at a multitude of scales and requires new technology for efficient monitoring and management. The introduction of unmanned aerial systems (UAS) provides researchers with readily available red–green–blue (RGB) cameras with high‐resolution capabilities, which may add considerable value to researchers and producers when assessing turfgrass performance. A study was conducted at the Ft. Lauderdale Research and Extension Center (FLREC) in Davie, FL in the spring (February–April) of 2023 to evaluate the performance of RGB vegetation indices (VIs) on ‘Celebration’ bermudagrass [ Cynodon. Dactylon (L.) Pers.] and ‘CitraBlue’ St. Augustinegrass [ Stenotaphrum secundatum (Walt.)] in comparison to visual ratings and Normalized Difference Vegetation Index (NDVI). Images were obtained by an RGB camera coupled to a remotely piloted Parrot ANAFI Thermal drone capturing images with 75% overlap. Both the Green Leaf Index and Green Chromatic Coordinate were highly correlated to quality readings in both grasses, with correlation coefficients as high as 0.92 in bermudagrass (outcompeting NDVI) and 0.88 in St. Augustinegrass (NDVI was more correlated). Each grass species had a unique correlation with each index, showing how different species and possibly cultivars may be better monitored with species‐specific VIs.