From the Pheasants Forever website:

"Must I use herbicides? Weed competition is the most serious threat your food plot will face. Thus,
we recommend some sort of herbicide treatment. Food plots planted without weed control will have highly
variable results. Weed problems can be addressed by tillage, chemical suppression, or a combination of both.
A few weeds in a food plot will actually improve the diversity of the area for wildlife. However, severe weed
competition that causes the primary planting to fail can waste your food plot investment, and puts your wildlife
in a bad position when winter arrives. Pay attention to weed control recommendations on the bag for best
results for your planting."