If you purchase most of your produce from supermarkets, price lookup (PLU) codes may be one way to determine if a food is organic or conventional. Foods that are produced organically typically have five-digit PLU codes that begin with the number 9. Conventional produce usually has a four-digit code that begins with a 3 or 4. Keep in mind, however, that this system is completely voluntary and not all produce will have this signifying label.
Source: International Federation for Produce Standards (IFPS). (n.d.).