Hyperspectral Analysis of Japanese Oak Wilt to Determine Normalized Wilt Index

Significant Japanese Oak Wilt has been widely spreading over the Japanese Islands since the 1980´s. We proposed a Normalized Wilt Index (NWI) based on NDVI and NDGI for the purpose of detecting the oak wilt from ASTER VNIR data. The NWI of wilt leaves indicated significantly higher value than those of healthy leaves in early stages of autumnal tints. The NWI of summer mountainous data realized a better wilt detection performance with low false positive in comparison with other NDVI, NDGI based methods. The NWI distribution based on ASTER data roughly coincided with a field inspection map as ground truth.