Identifying Subalpine Fir (Abies lasiocarpa) Attacked by the Balsam Woolly Adelgid (Adelges piceae) Using Spectral Measurements of the Foliage

Figure 4

Values for the red green index (ratio of bands centered at 660 nm and 549 nm, resp.), percent reflectance in a narrow band centered at 670 nm, and percent reflectance in the narrow band centered at 1912 nm for individual trees infested or not infested with balsam woolly adelgid. The three variables were selected using a stepwise discriminant analysis procedure for distinguishing infested from noninfested trees.