Nutgrass or Mullumbimby Couch? Not sure……until you have a look at the plant’s flowers or root systems.
Both look similar and both can be selectively removed from all warm season grasses including Buffalo, Couch, Zoysia, Kikuyu etc with one of the following herbicides: Monument (in couch grass only) and Sempra / Sedgehammer (all warm season grasses).
Sempra (by Nufarm) & Sedgehammer (by Amgrow) are the same active constituent. Sempra was the original patented product.
Nutgrass’s roots are characterised by a bulb whereas the roots of Mullumbimby Couch have rhizomes (or underground spreading roots).