Comparing traditional and unmanned aerial vehicles (UAV) assessment methodologies in aquatic weed control research

Abstract

Weed control research involves pre and post treatment measurement of various plant attributes to determine treatment efficacy. Aquatic systems are challenging environments presenting specific risks, such as crocodiles, when conducting aquatic weed control trials in tropical Australia. The rapid emergence of technologies such as unmanned aerial vehicles (UAV’s) provides the opportunity to remotely collect data via the capture of high-definition imagery; therefore reducing risks whilst conducting research within aquatic systems. UAVs collect data in various parts of the electromagnetic spectrum including visible and infrared (which is particularly relevant to plants due to chlorophyll production). The use of drone-based assessment technology has the potential to augment, if not replace, traditional methods of determining herbicide efficacy. This study compared traditional ground-based (live stems counts and visual damage scores) collected data with remotely sensed UAV (Red Green Blue (RGB) and multispectral images for photogrammetry processing) data to determine whether UAVs could be used to assess the efficacy of field herbicide treatments on the ponded pasture species, Aleman grass (Echinochloa polystachya) (Kunth) Hitch.
There was a strong correlation between on-ground and aerial efficacy assessment results for some of the treatments. The correlation was consistent across the higher levels of treatment damage. The use of remotely captured imagery obtained via the UAV proved to be a reliable method for assessing treatment effects over time.