The herbicides that you won't mention may or may not have a residual still present at harvest time it depends on which ones. Some farms will have zero chemicals sprayed on them during the growth season, although extremely rare in Oklahoma. Every no-till operation will, every conventional farmer that gets behind will have a farm sprayed on occasion.
Some how you went from "Sprayed before maturity to have less weed seeds when harvested." which is what I questioned, to
"The herbicide residue can be in the ground at planting time and the wheat can take it up without damaging it. But will still have effect on non grass crops".
Herbicides on a crop work on a growing plant, broadleaf plants aren't growing during the fall and winter.
In 2013 a variety of wheat developed at OSU called DoubleStop was released. It was created (not GMO) to work with the herbicide Beyond + MSO. It's used to knock out cheat grass, goat grass and rye infestations. Even though those are all grasses like wheat, the DoubleStop variety isn't effected by that herbicide. It costs $60 an acre to plant plus chemical application 2x, which is pricey so it's seldom seen. Any other grass herbicide will not only kill the unwanted grasses in your wheat, it will kill the wheat too. That's why "Sprayed before maturity to have less weed seeds when harvested" doesn't happen. Nobody is out there spraying Roundup on their wheat before harvest lol.
