Non-destructive techniques of detecting plant diseases: A review

Plant diseases contribute to significant economic and post-harvest losses in agricultural production sector all over the world. Early detection of plant diseases and pathogens is crucial for maintaining the sustainability of the agricultural sector. In this regard, non-destructive techniques are one of the most practical and feasible ways of monitoring health conditions of plants for real-time applications. Current methods that involve molecular and serological methods are time-consuming, laborious, and require complex procedures. Hence, non-destructive methods are preferable since no sample preparation and repetitive processes are needed for the measurements. The prevention of plant disease and pathogens during the preliminary stage aids to the health control and yield optimisation without depending on the pest and pesticides usage. These techniques are boosted by the development of advanced technologies where computer-aided systems are employed for monitoring plant diseases. It is also vital to analyse the disease spread in plants for overcoming the issues related to physiological and biological states in crop protection. Most often a wide range of non-destructive techniques is needed to provide rapid detection of plant infections even in the case of one plant type. This study reviews the applications of nondestructive techniques including image processing, imaging-based, spectroscopy-based and remote sensing methods in monitoring and detecting plant diseases. The non-invasive techniques have also been investigated for their fundamental concepts and potential applications in developing sensing devices for fieldwork.