Detection of plant diseases using biosensors: a review

This review presents some of the pathogen causing diseases in plants, their effects towards crop loss, their various sensing methods for identification. The adverse effects of the pathogen causing diseases in plants, particularly in agricultural industries, has led to global economic losses and has remained a major challenge to deal with. The continual increase in agricultural losses has led to a tremendous interest in the development of pathogen detecting devices for early identification of diseases. The current methods for plant disease detection are classified as direct or indirect methods. Most direct methods like the conventional PCR (polymerase chain reaction) and ELISA (enzyme linked immunosorbent assay), are molecular and serological methods with a wide range of application in plant disease detection but are labour intensive, time-consuming and require detailed data sampling and processing. While indirect methods are inherently optical or imaging techniques such as hyperspectral imaging, thermography, gas chromatography, and fluorescence imaging. Indirect methods are sensitive methods with high data capacity, but its sensitivity due to hypersensitiveness to environmental changes and atmospheric changes could lead to a reduced detection limit in early detection application and their specificity. With limitations such as false positive and photo-bleaching results, which are issues associated with these methods, there is a need for novel biosensors for early disease detection in plants which can aid in reducing the spread of economic and post-harvest losses in agricultural industries. Novel techniques like optical biosensors and electrochemical biosensors have also been fabricated for pathogen detections in plants with advantages like easy to use, portability, less expensive and can be used for early detection of diseases.