Something very similar to that has already happened - in (very often hand-weeded) rice, shattering appears to have evolved to de-domesticate the crop - making it essentially impossible for 'weedy' rice to be distinguished from the real thing - https://www.sciencedaily.com/releases/2013/07/130717132418.h...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2988683/