Infrared images can detect stress in crops before it is visible with the naked eye. Healthy
canopies reflect strongly in the infrared spectral range, whereas plants that are stressed will
reflect a dull color  The stress might be from lack of water, insect
damage, improper nutrition or soil problems, such as compaction, salinity or inefficient drainage.
The farmer must assess the cause of the stress from other information. If the dull areas disappear
on subsequent pictures, the stress could have been lack of water that was eased with irrigation.