http://blog.friendseat.com/how-to-id-genetically-modified-food-at-the-supermarket

For conventionally grown fruit, (grown with chemicals inputs), the PLU code on the sticker consists of four numbers. Organically grown fruit has a five-numeral PLU prefaced by the number 9. Genetically engineered (GM) fruit has a five-numeral PLU prefaced by the number 8.

For example:

- A conventionally grown banana would be: 4011
- An organic banana would be: 94011
- A genetically engineered (GE or GMO) banana would be: 84011