I was at the NOFA NJ Conference this past weekend and picked up an app card for Bejo's Cropalyser App. It's really cool. Provies detailed info about pest and diseases in beets, carrots, cabbage and onions. It has pictures to help you identify the problem. It also has info about bacteria, fungi, insects, nematodes, viruses and nutrient disorders.
Go to Bejo's Cropalyser App to download.