Fall seeding herbicide

Hi guys I have 11 acres I'm going to seed this fall. It will be an alfalfa stand with a few pounds of orchard grass mixed in per acre.. now it was suppose to be seeded with an oats cover crop this spring but time didn't allow for it to happen. Last year it had wheat in it and beans in it the year before (leased to another farmer.) Now there is some foxtale and other junk growing up in it. What can i spray that will kill all the foxtail and also have a nice residual effect so hopefully it will kill any other weeds that may come up in early August. I want to disk around 8-15 and plant a day or so later. Also this will be my first fall planting of alfalfa so any advice will be great

Fall seeding herbicide