Disease Proof

They tell a story.

According to Food & Wine (via Megnut):

The numbers tell you how the fruit was grown. Conventionally grown fruit has four digits; organically grown fruit has five and starts with a nine; genetically engineered has five numbers and starts with an eight.

Megnut also has word that you will basically never see a five-digit code that starts with an 8, because papayas (84394) were the only GM foods to get their own code so far.