GARDENING Does nutgrass drive you nutty?
No stopping this veracious weed known the world over HOW CAN I GET RID OF NUTGRASS?
With TAFE Queensland South West horticulture teacher Paul Luck Answer: Nutgrass, or Cyperus rotundas, is a problem weed all over the world. In the USA it’s known as purple nut sedge, in South Africa it’s wintjiekweed or red grass, teki in Indonesia or motha in India. From ancient times, rhizomes and tubers of this weed have long been used as a herbal remedy to treat bowel and stomach disorders in several countries including China, India, Iran and Japan. As you can see, we are not the only ones dealing with this little green shoot and it’s actually commonly referred to as the “world’s worst weed”!
There is no question that nutgrass is a very persistent pest for the gardener and landscaper, and it doesn’t end there! I have seen nutgrass shoot through thick asphalt and pool liners; there just seems to be no stopping this pest.
It has been shown that nutgrass can remain dormant or inactive in soil for up to 10 years. The nuts that lay below the surface in soils will shoot after being disturbed by movement. Anything that shifts and cracks the earth allowing water and oxygen deeper into the soil may activate the dormant nuts. For example, I demolished a concrete slab under an old Queenslander a number of years ago and had nutgrass growing within a week.
Nutgrass grows best in full sunlight when adequate nutrients are available. It gets out of control when allowed to grow without competition from other plants, but only competes well in perfect growing conditions. It is for this reason that infestations are often noticed for the first time when we spend a little time in our gardens. Fluffing up, cultivating or improving the soil, importing soil, fertilising, weeding, removing old plants and heavy watering are all activities that can disturb nuts and encourage them to shoot.
Glyphosate is the common ingredient in many store-bought herbicides and is often marketed as Roundup or path weeder which you can use to fight this weed. Glyphosate is a non-selective herbicide and will kill any plant that it contacts, so be very careful what you spray. It is referred to as a translocation killer of weeds and will travel through the nutgrass into the nuts and kill the whole plant. You will require a number of treatments.
For situations like in the home lawn where you need to avoid killing your grass, look for a chemical with the active constituent halosulfuron-methyl. This chemical is commonly sold as Sempra.
Sempra inhibits a key enzyme in the plant’s metabolic pathway and stops plant growth. Plant death occurs 14 to 21 days after initial application. Unlike glyphosate, halosulfuron-methyl does not translocate throughout the attached tubers, so multiple applications may be required if the infestation is particularly advanced. In some cases, a one-off treatment is sufficient.
In my opinion, chemical control is the most effective way of ridding your gardens of nutgrass.
Hand pulling normally only causes the weed to send out more nuts. Read the chemical instructions for best results.
Disclaimer: The comments provided in this article are general in nature only and are not a substitute for professional advice. The author accepts no responsibility for any action taken by a reader in relation to this article.
WEED: Nutgrass is a most invasive weed, having a worldwide distribution in tropical and temperate regions.