4 February 2025. Paul McIntosh, Pulse Australia and WeedSmart.
I believe the number one weed in the world is couch grass, remembering that a definition of a weed is plant out of place.
However, I sure would like to know where nut grass comes in that weed ranking score.
Of course, when I say nut grass there are a quite a few contenders in this description.
They all have their own painful ways, however, from your inner city grass lawns and suburbia, onto peri urban areas right through to our red and black soil farming and livestock country, the plethora of these Cyperus (its genus name) type plants is large. These Cyperus plants can pop up anywhere and can be very competitive to other plants in our rural environment. Even my own relatively new lawn or grass area has these undesirable nut grass plants growing, until my herbicide plan gets going.
For a start for your information, these sedge plants are not a grass type species. They look like a grass, however they are really a sedge. For professional farming properties, that means the herbicide mode of action of Group 1 (was A) will not work for any of these Fops, Dims or Dens.
However, part of the Group 2 (was B) mode of action herbicide called Halosulfuron can do a reasonable job in agricultural scenes and the common house yard. However, it is never just a one spray event to control all these brown tubers or root systems/nuts (really a swollen tuber), plus the above ground green shiny leaves controlled to all go away. You really need to keep at it with possibly several herbicide applications and stop mowing your grassy lawn before and after spraying for at least 10 days is my best advice. Especially take note of the label for any possible sensitive grass species.
The other control method is just digging up all the nuts and tubers and putting them in the long acting compost bin or to the local dump.
For my farming fraternity, control by herbicide usually includes more than just using glyphosate. Sedges like these react to broadleaf herbicides like 24D and Picloram plus a few others in our paddock.
Of course, Glyphosate has been used for decades controlling plants out of place of which nut grass is certainly one of these undesirable species.
Many a time in my decades of agronomy in broadacre farming environments, I have recommended at least two summer applications of a Gly and 24D tank mix, if nearby susceptible crops and plant back restrictions allow on these nutgrass infested paddocks.
Re-seeding from the nut grass seed head is not the major means of nut grass spread or occurrence in your yard or paddocks, it is the regeneration or proliferation of the tubers and nuts under the ground that are your major spreading events. That and the shifting of soil or the use of any Tyned implements working through patches of nut grass in cultivation blocks.
It may not be the world’s number one weed, however, this plant ranks very high on my list of undesirables wherever it is.
That’s all folks.
Nut grass in a Darling Downs paddock