You’ll find a sticker on all grocery store produce, Dr. Friedman tells Reader’s Digest. The sticker is known as a “PLU.” Here’s how to crack its numerical code:
Organic produce has a five-digit code beginning with “9.”
Conventionally grown produce has a four-digit code.
GMO produce begins with “8.”
https://www.tasteofhome.com/article/this-hidden-code-on-your-food-means-its-genetically-modified/
For produce, 4 digit code is not GMO but pesticides have likely been used.