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Thatch grass (Hyparrhenia rufa)

Thatch grass forms dense stands that outcompete native plants and reduce habitat for native animals. It can also increase the frequency and intensity of bushfires.

Key facts

Type: Weed, grass.

Native to: Tropical and southern Africa and Madagascar.

Established in: QLD, NSW, WA, NT.

Other names: Jaragua grass, thatching grass.

Identification

  • It is an erect, densely tufted grass that grows up to 3 m tall.
  • Mature plants often retain clumps of brown, dry leaves that look thatched.
  • Leaves are flat, up to 60 cm long and 8 mm wide, and usually smooth with rough edges.
  • Reddish seedheads are usually present in summer and have paired branches forming a V, with 9 to 10 awns on each branch.
  • The hairy seeds have a brown awn about 2 cm long, twisted with two bends.
  • Look-alike: Coolatai grass (Hyparrhenia hirta) looks similar but grows only to 1.5 m tall, and each seedhead branch has 5 to 8 awns.
  • Look-alike: Tambookie grass (Hyparrhenia filipendula) is a native grass that grows only to 1.5 m tall; its seedhead branches are up to 2.5 cm long and have 1 to 3 awns each.

Where it grows

In NSW, most infestations have been found in the Hunter region, with records also from the North Coast, North West, Central West, Greater Sydney and South East regions, in grasslands, dry forest, pastures and disturbed sites such as cultivated land and roadsides.

Why it matters

  • Dense stands outcompete native vegetation, especially in grasslands and woodland understoreys.
  • It reduces habitat for native animals.
  • It competes with crops and contaminates seed.
  • It can contribute to more frequent and intense bushfires.

How it spreads

  • Long seed awns can attach to clothing, boots and animal fur.
  • Seeds are also spread by wind and slashers, especially along roadsides.
  • Germination often occurs after fires.

Control options

  • Dig small plants out by hand.
  • Use registered herbicides only in line with the current product label and permit, as the best spray timing varies between products.
  • Ensure fodder brought into clean areas is weed free.

Hygiene and washdown

  • Clean boots, clothing, equipment and vehicles after working in areas with thatch grass.
  • Check that fodder brought into clean areas is weed free.
  • 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: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Declared weed, Class A. Class A: to be eradicated. All declared weeds are also Class C, so they must not be brought into the NT.
  • 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
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources