I am planning to have stonewall put on st augustine and burmuda at about a pound per acre. I am mainly concerned about broadleaf weeds. Most of the area are mixed grass. Are there and downside? Any significant risk in hurting st augustine growth? The temperature is ranging from 37-60F each day. Plan to put grandular fertilizer on when green up start. And will use herbicide down the line no weeds visable now.