Research imagery and spectral characteristics of rice sheath blight using three portable sensors
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Copyright (2015) by the American Society of Agricultural & Biological Engineers All rights reserved. Sheath blight is the most important disease in rice in the southern US. The utilization of remote sensing technology to detect the development of the disease and use precision aerial fungicide application for control of the disease is of great research interests. In this study, the Agricultural digital camera (ADC), field spectrometer (Analytical Spectral Devices, ASD) and chlorophyll meter SPAD-502 were used simultaneously to collect imagery and spectral data of sheath blight on 21 rice cultivars. The normalized difference vegetation indices (NDVIs) were calculated from multispectral images; meanwhile, spectral characteristics of healthy and diseased rice plant canopies at different growth stages were analyzed. The results indicated that multispectral ADC was able to recognize the disease levels better than SPAD-502 when rice sheath blight developed to its characterized symptoms. Because of its early detection of disease, ASD spectrometer can provide timely technical support for disease detection in the field. Moreover, the sensitive spectral regions of rice sheath blight were determined at 405-530 nm and 550-730 nm while the sensitive spectral bands for disease identification were at 488 nm, 489 nm, 492 nm, 493 nm, 677 nm and 680 nm. These research results are useful to detect rice sheath blight in the field and develop precision aerial fungicide application for economic management of sheath blight in rice.