You want a combination. The effects of two herbicides don't add, they multiply.
I'm assuming you don't have an applicator's license for restricted use herbicides... (I do)
If you can find full strength roundup (4 - 4.8 # a.i./gal) and 2-4,D (ester
20% a.i.), apply each at 2 quarts per acre with 1 quart per acre crop oil. Ammonium sulfate will greatly enhance effect at about .25#/gallon of spray. Wait until you have significant foliage and a nice warm actively growing day.
Of course, if you can find Garlon, Tordon, or the old 2,4,5,T (that's agent orange main ingredient- now illegal) you don't have to pussy foot around.
If you want to put down a pre-emergent to keep an area weed free of new germination, you should be able to find Princept. re-apply 2/year, don't go over label rate if you care about your local well water supply.
Karl