Spraying pre and post emergent herbicide

We have started spraying the entire golf course (except the greens) with our second application of our winter pre emergent herbicide. We spray two half rates instead of the entire rate because we feel it gives us better long term control. The difference this time is we have added a post emergent herbicide in the tank. We are spraying glyphosate (the active ingredient in Roundup) at a rate of just 16 oz / acre. At this rate, it should knock out any weeds that have germinated. With the Bermuda being dormant, the glyphosate will not harm it. Even if it isn't completely dormant, the heavy frosts form the last week have shut down the Bermudagrass where it isn't taking up any nutrients or chemicals. This is a good trick to use in your yards as well if you have Bermuda or zoysia grass. I wouldn't recommend if you have Centipede or St. Augustine.