Herbicide resistant crops- This allows the farmer to spray wide spectrum herbicides on the crops and kill only the weeds.
Also, if you apply herbicide to kill broadleaf weeds, that should be done in October.
Vinegar may work just as well, just be sure it is diluted in water because vinegar can kill plants and is often used as a natural herbicide to get rid of weeds.
Bradford corn gluten is an organic lawn care product, effective as both fertilizer and herbicide.
Pesticide usage is an area of concern which organic agriculture addresses.The same standards apply to pesticide usage, with methods such as crop rotation rather than herbicide use.