Crop diseases often occur in non-uniform patterns throughout the field. The patchy distribution of soil-born diseases creates the possibility for growers to use precision agriculture tools to manage disease dispersion. In most instances pesticides are applied uniformly irrespective of the distribution of disease; thus increasing production cost and increasing negative risk to the environment. Consequently, having a device that can distinguish between healthy and stressed crop canopy and further make a disease map of the field would be beneficial to farmers.