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Yellow nutgrass (Cyperus esculentus)

Yellow Nutgrass is less commonly naturalised in Australia than Nutgrass, but it is a pest in some Queensland crops. It can invade crops and natural environments, and its underground tubers make it difficult to eradicate.

Key facts

Type: Weed, herb.

Native to: Probably southern Europe and northern Africa.

Established in: QLD, NSW, VIC.

Other names: Yellow Nut Sedge, Yellow Nutsedge, Chufa, Tiger Nut.

Identification

  • It is a slender perennial sedge with smooth, triangular stems 10 to 70 cm high and 1 to 4 mm wide.
  • Its grass-like leaves are 3 to 6 mm wide and can be longer or shorter than the stems.
  • Slender underground rhizomes produce round to egg-shaped tubers about 1 cm across, with a yellow-brown coat.
  • Its flowering clusters have yellowish to golden-brown flowers on branches up to 10 cm long.
  • Its small fruit or seed is grey-brown, broadly triangular in cross-section and about 1.5 mm long.
  • Look-alike: It can be confused with introduced Nutgrass (Cyperus rotundus) and native Cyperus bifax and C. victoriensis. Yellow Nutgrass has yellowish to dark golden-brown flower heads, usually hairy flower branches, yellowish-brown rhizomes and round to egg-shaped tubers; the other species have darker reddish or purplish-brown flowers, hairless branches, darker rhizomes and more oval, fibrous but non-hairy tubers.

Where it grows

In Australia it is naturalised sporadically, mostly in coastal areas of eastern New South Wales, Queensland and Victoria, and occurs in disturbed places such as parks and gardens and occasionally in agricultural areas.

Why it matters

  • It can invade a large number of crops and can also invade natural environments.
  • In Queensland it has been reported as a pest of summer crops on the near north coast and sugar cane on the far north coast.
  • Its underground tubers and rhizomes make it difficult to eradicate.

How it spreads

  • Small tubers in the soil enable vegetative spread.
  • It produces seeds occasionally.

Control options

  • Control measures used for Nutgrass are likely to be effective, including a combination of chemical spraying and cultivation.
  • Repeated deep cultivation can be effective, but if it is not sustained it can stimulate growth.
  • Eradication is difficult because of the extensive underground rhizomes and tubers.
  • Selective herbicides used alone are not effective enough; use approved methods and seek current chemical information from the Australian Pesticides and Veterinary Medicines Authority.

Hygiene and washdown

  • Strict hygiene and preventive measures can help contain infestations because spread is largely by human activity.
  • Avoid moving soil or tubers from infested areas on machinery, boots or other gear.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Declared pest (C1), prohibited. C1 Exclusion: to be kept out of WA, or out of the parts of WA where it is not established. Report any sighting to DPIRD. It must not be brought into WA (prohibited organism).
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria

Sources