Late Blight Detection in Tomato Fields by Aerial Photography with Natural and Infrared Color Film

(...) Spectral densitometric measurements made on films from 400 to 700 nm in increments of 10 nm showed two intensity peaks with both types of film. Dividing the first peak by the second peak produced a ratio greater than 1 that correlated significantly with integral and transmittance measurements of color infrared photographs of diseased plants. Spectrophotometric measurements of color infrared photographs detected late blight on tomato plants better than visual observation of photographs