Hyperspectral Remote Sensing for Advanced Detection of Early Blight (Alternaria solani) Disease in Potato (Solanum tuberosum) Plants Prior to Visual Disease Symptoms

Abstract. Early detection of disease and insect infestation within crops is essential to reduce potential production losses, reduce environmental risk, and reduce the cost of farming. The objective of this study was the detection of early blight (Alternaria solani) in potato (Solanum tuberosum) plants at two different growth stages using a handheld hyperspectral spectroradiometer. Hyperspectral reflectance spectra were captured 10 times over five weeks from plants grown to the vegetative and tuber bulking growth stages. The spectra were analyzed using cluster analysis and the vegetative indices, simple ratio (SR) and normalized difference vegetative index (NDVI). For SR, wavelengths used were 665 nm and 770 nm; for NDVI, wavelengths used were 670, 695, 735, and 945 nm. Both cluster analysis and the vegetative indices SR and NDVI successfully distinguished moderately diseased plants from healthy and minimally diseased plants. This study demonstrated the capability of cluster analysis and the vegetative indices SR and NDVI for the detection of early blight in potato plants.