We've got about 1.5 ac to kill off before power raking and hydromulching. There's crabgrass, dallisgrass, misc broadleafs and native common bermuda. We're planning on using Riviera. The problem is, with backpack spraying of roundup, it takes forever to cover the area, and because much of it is bare already, the weeds come back before the die-off is complete. Any suggestions on a different application method, or herbicide that'll be safe to use before hydromulching?