Here is the situation; my mom's front lawn is about 60% St Aug, 20% Centipede & 20% bermuda. The St Aug is slowly creeping and taking over the other 2. I would like to encourage the St Aug and have the lawn mainly this 1variety. What would you do to promote the St Aug without chemically killing out the other 2. The different grasses are divided up in distinct patches, it is not mixed. Was thinking of using practices such as mowing the other 2 differently and not fertilizing them. What would you do?