Eli5: How do farmers keep poisonous plants from growing in crops and being harvested and packaged with edible plants?

Question

Eli5: How do farmers keep poisonous plants from growing in crops and being harvested and packaged with edible plants?

In: Other

Answer 1

Long story short… Firstly the undesirable plants are minimized in their efforts to seed by using herbicides . Later, at harvest, the combine sifts out the finished crops desirable kernel, seed, etc. You can set the desired size which helps minimize error.
Then everything else is spit out the back of the combine and ground back into the land at a later date. This provides product mostly free of anything undesirable. The farmer takes it to the local elevator for further handling/cleaning and then further processing at various stages. Yada yada.