Disease recognition from images having a large field of view

A computer system and related computer-implemented methods for recognizing crop diseases from large FoV images are disclosed. In some embodiments， the computer system is configured to initially build a first digital model in memory for identifying a region capturing a leaf， and a second model for identifying a region capturing a leaf infected with a disease. Given a large FoV image， under program control， the system is programmed to then automatically identify candidate regions that might capture single leaves from the large FoV image using the first model. The system is programmed to further determine whether the candidate regions capture symptoms of a crop disease on single leaves using on the second model.