Advancements in sensor-based weed management: Navigating the future of weed control

Controlling weed populations in agricultural land is challenging due to various factors, such as soil conditions, crop type, and environmental conditions. Substantial experience is needed to develop a strategy for minimising pressure from weed infestation. For a relatively longer period, weed control was taken care of using herbicides and mechanical and manual weeding. While herbicides simplify weed control, they pose issues like residual effects and the development of herbicide resistance in weeds, necessitating the deployment of alternate smart weed-management technologies. Lately, smart weeding robots and sensor-based site-specific spraying systems have been developed. Sensors as varied as hyperspectral imaging cameras, Global Navigation Satellite System (GNSS), Real Time Kinematics-Global Positioning System (RTK-GPS), optoelectronic, fluorescence sensors, laser and ultrasonic systems can help to improve weed control efficacy when combined with mechanical and spraying robotic systems. Camera-steered mechanical weeding robots and unmanned aerial vehicles are now widely available for weed management. This review focuses on the developments in sensor-based mechanical and chemical weeding, identification of herbicide-resistant weeds, and herbicide effect assessment. This is a comprehensive overview of studies of sensor-based weed-management strategies being adopted worldwide. Furthermore, an outlook towards future sensor-based weed control strategies and necessary improvements are given.