Discing for that stuff is a waste of time if you have enough rain coming. It'll grow on bare ground if you have enough rain coming.
Kill whatever is standing, let it die and wait for a sure enough rain. Broadcast your stuff and mow or roll what you killed down over it. It works with seed as large as tillage radish.
In your case you're most of the way there. I repeated the words enough and rain on purpose. That's the key. Having done this a couple times now I won't disc again.
Not even a 24hourdumpsterfire troll is foolish enough to put ryegrass in a bait plot.
