Use of multispectral radiometry in wheat yellow rust experiments1

Winter-wheat field fungicide experiments were monitored by multispectral radiometry to determine yellow rust impact on crop growth and to predict yield loss caused by disease. Spectral reflectance data were highly correlated with yellow rust severity. Linear regression models with spectral ratios as independent variables explained 90–93% of the variation in yield between plots with different treatments of fungicide. The area under the NIR/Red curve, calculated from heading to soft-dough growth stages, was a good predictor of yield loss determined at harvest.