Price: $99.99

FieldScout GreenIndex+ enables growers to manage the nitrogen needs of crops by taking a picture on their smartphone. The app is used in partnership with a color board held behind the plant leaf to reference true color in various lighting situations. The app adjusts for those light levels and computes a dark green color index, eventual providing nitrogen application rate recommendations for corn. "The app allows farmers to make these nitrogen application decisions themselves," said Mine Dunning, VP of Product Development, Spectrum Technologies, Inc. All results are georeferenced, logged, and can be emailed for archiving or further analysis.