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Giant rat's tail grasses (Sporobolus pyramidalis, S. natalensis and S. fertilis)

Tough, unpalatable tussock grasses that invade coastal and sub-coastal pasture and roadsides. A single plant can drop tens of thousands of sticky seeds that hitch a ride on slashers, vehicles and cattle.

Key facts

Type: Weed, grass.

Native to: Africa and Asia.

Established in: QLD, NSW, NT.

Other names: Giant Parramatta grass.

Best time to act: Treat actively growing plants from late spring to autumn, before seed heads mature.

Identification

  • Large tussocks up to 2 m tall with tough, narrow leaves.
  • Seed heads either spike-like (rat's tail) or open and pyramid-shaped, depending on the species.
  • Seeds become sticky when wet and cling to machinery and animals.
  • Look-alike: Native and naturalised Sporobolus species such as Parramatta grass look similar; confirm with a seed head sample.

Where it grows

Pasture, roadsides, rail corridors and disturbed land in eastern Queensland and northern New South Wales.

Why it matters

  • Low feed value reduces carrying capacity.
  • Hard on cattle teeth.
  • Dominates roadside and pasture vegetation.

How it spreads

  • Seed on slashers, vehicles, cattle and in hay.
  • Road maintenance and construction moving between areas.

Control options

  • Spot spray isolated plants with registered herbicides before seed set.
  • Maintain competitive, well-fertilised pasture.
  • Map roadside infestations and slash from clean areas to infested areas.

Hygiene and washdown

  • Clean slashers, mowers and vehicles before leaving infested roadsides and paddocks.
  • Buy hay and seed that is certified clean.
  • 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: Restricted matter, category 3. Do not give it away, sell or release it into the environment. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Regional priority in 4 of 11 regions. Regional priority weed in Central Tablelands, Greater Sydney, Hunter, North West. 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: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • 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
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources