Nutgrass Treatment Guide

  • About Nutgrass
  • Identifying Nutgrass
  • Treatment

About Nutgrass

Nutgrass (Cyperus rotundus) also known as nutsedge is not an actual grass. It is a perennial sedge. Sedges are a graminoid or a plant that resembles a grass. 

Nutgrass is a major pest weed in Australian backyards, gardens and in agriculture. It is well known for it’s stubbornness of coming back when you think you have eradicated it.

Luckily Nutgrass is easy to identify and treat.

Nutgrass Infestation
Nutgrass Flowers, Seeds

Identifying Nutgrass

Nutgrass grows to between 20 and 50cm tall. Stems are triangular in a cross-section, smooth and erect. Leaves 2-7mm wide are glossy in look and dark to bright green with a prominent vein on the underside of the leaf. You can feel a slight serration in the leaf. Plants can have up to 20 leaves which in general emerge near ground level in rows of 3.

The flowers are a cluster of flattened spikelets of a purple-reddish brown. The flowers emerge from thin stalks.

The name ‘Nut’grass derives from bulbs, roots, rhizomes, and multiple tubers (the nuts) underground.

The ‘nuts are irregularly shaped and up to 3 cm in length and dark brown.

Each tuber has multiple buds, most stay dormant until an active shoot is destroyed. Dormant tubers can be viable in the soil for 3-4 years and up to 10 years in ideal conditions.

One of the main reasons this weed is difficult to eliminate is because of these dormant tubers. They are the growing point for the plant and sit between 4 and 20 cm below the surface of the soil, the root system can extend 1.2 metres below. That is why when you mow the first thing to pop back up is the nutgrass, destroying the leaves does not harm the plant.

Nutgrass Treatment 

There are 2 methods to control nutgrass weeds- physical and chemical. Chemical methods are highly successful.

Nutgrass Removal

Physically pulling the weeds out is a good control method if there are very few weeds. To be effective the entire weed needs to be extracted, nut and all. If a single nut is left, the weed will be back in a matter of days. Physical control methods are not suitable for large areas of ground or weed infestation.

Nutgrass Poison

Option 1. Selective Herbicide Mix 0.65g Kenpra in 5L of water and apply 5L of the mix per 50m2. Apply Kenpra 750 WG Herbicide to actively growing weeds when new growth has reached a minimum of 5cm. This products targets sedges and can be used without harming other plants or lawns. This is suitable for larger areas of land such as small acerage, schoolyards, parks and sporting fields.

How to Kill Nutgrass with Kenpra

Option 2. Non selective control For some suburban properties, spot managing with a broad spectrum herbicide such as glysophate is economical and fast way to eliminate the weed. Mix 1.6mL of Tuffweed 360 in 1 Litre of water and apply to actively growing plants in late Summer/Autumn (Feb-April) when at least 20% have reached the head stage. A spray marker dye can be used to ensure accurate spraying and reduce overspray.

Always read product label prior to use.
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