Although this website doesn’t exist anymore, this is an example of the mis-information out there regarding turf knowledge and Lawn Care (in particular).
Contrary to what this old website says, Nutgrass and Mullimbimby Couch can be selectively removed from just about all desirable grass species.
There are two (2) selective lawn herbicides for this job, they are Sempra (made by Nufarm) and Sedgehammer (by Amgrow).
Both are similar prices as the Sempra product is off patent.
These products are very good for the control of Nutgrass and Mullimbimby Couch weeds. These weeds usually pop up in lawns that are over watered, so best to maintain a lawn watering regime that is Heavy but Infrequent, and nil water in Winter.