Which works best in the south or do you rotate them?

A full rate of metribuzin really makes Gramoxone hot here.  It is important to start clean and try to stay as clean as you can.

I am still learning about the other products you mention for later on.

http://weeds.utk.edu/WeedTemplate_files/WeedControlManual/FINAL%20COMPLETE%20DRAFT.pdf

https://www.google.com/#q=roundup+or+gramoxone+burn+down%3F

Ed