Using Grape Leaf Reflectance for Spatially Variable Vineyard Management

Abstract

Spectral reflectance of grape leaves was measured over the range of 450-2400 nm. Reflectance spectra of leaves from healthy and phylloxera-infested vines were compared and significant differences were noted in the visible part of the spectrum. A Green-Red Ratio (GRR) was evaluated to distinguish between the two groups of leaves. The GRR was also tested against leaves of different nitrogen tissue levels from otherwise healthy vines. While showing a positive correlation with leaf nitrogen content, the relationship was not significant for effective diagnostic use.