According to the label, the lowest rate is 1 gallon per 10,000 sq ft. When doing a bare ground job, especially over a large area, consider the cost of an application failure or weed breakthrough. Who pays for you to re spray the area or take care of weeds that have popped up here and there? I do not mind an expensive spray mix if it means everything is dead and not going to come back for the rest of the year.
Pramitol runs no matter what rate you apply it at. Sadly, desirable trees and shrubs are more sensitive to it than the weeds. I also notice that grassy weeds are hard to control with it. That is where Sahara shines. If there is high grassy weed pressure, I add the maximum rate of oryzalin to the mix. However, this does not cover leguminous broadleaves and brush very well. Escort helps with that.
DuPont published some literature on bare ground weed control programs for various regions of the US. They do push their bare ground herbicides, however mention is made of other herbicides. Good take home points from the literature include knowing what kind of weeds are present, timing, and good application practices. It can be amazingly hard to provide total vegetation control. I think it is harder than weed control in lawns.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738