My nieghbor installed a Floratam lawn this spring. It is now being taking over with Crabgrass, Alexandergrass, Crowsfeet and a little Bermuda. There is no selective chemical control for these grasses. (Well Asulox for Crabgrass but no longer legal on residential). He told her not to pull them because in the process she would cause seeds to spread throughout her lawn. Is there any truth to this?