This is something we should all know. If you can’t buy local or from a farmers market you should pay close attention to the sticker. (from Garden Frugal)
The PLU code on your produce sticker can help you determine if your food is conventionally grown, organic or genetically modified (GMO).
4 digit PLU codes in the 3000 to 4000 range are reserved for conventionally grown produce.
5 digit PLU codes starting with a 9 identify organically grown produce.
5 digit PLU codes starting with a 8 identify genetically modified produce.