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Mexican feather grass (Nassella tenuissima)

Mexican feather grass is a prohibited weed in NSW that can invade pastures and bushland. It takes over pasture, reduces pasture quality and threatens native grasslands and woodlands.

Key facts

Type: Weed, grass.

Native to: Southern USA, Central and South America.

Established in: QLD, NSW, ACT, VIC, TAS, SA.

Other names: elegant spear grass, Stipa tenuissima, white tussock, Texas tussock grass.

Best time to act: Look for seedlings from mid spring to summer; treatment is most effective on actively growing, stress-free weeds, with glyphosate best at the early seedhead stage and flupropanate particularly effective in warm periods.

Identification

  • It grows in dense, upright tussocks up to 70 cm tall, with central leaves usually tallest and upright and outer leaves often shorter and bending away.
  • Leaves are tightly rolled, smooth when rolled between the fingers, coarse when you slide your fingers down them, 0.25–0.5 mm wide and up to 60 cm long.
  • The ligule at the leaf base is papery, smooth, milky coloured and 0.5–2.5 mm long.
  • Green or purplish seedheads grow in clusters 15–25 cm long on smooth, hairless spikes; seeds are 2–3 mm long and have an attached awn 4.5–9 cm long.
  • Look-alike: Serrated tussock (Nassella trichotoma) has drooping rather than erect flower heads, is shorter at about 45 cm, and has a wider seed and much shorter awn of about 25 mm.

Where it grows

In NSW it has been found in gardens at Tenterfield and Tamworth in 2006, around Leeton in 2018 and Lithgow in 2019, and at Barden Ridge in 2020; these plants have been controlled or are under an eradication program.

Why it matters

  • It takes over pastures, is unpalatable to stock and reduces pasture quality.
  • It can contaminate hay and grain.
  • It invades native grasslands and woodlands and competes strongly with pastures, grasslands and woodlands.

How it spreads

  • Each plant can produce up to 100,000 seeds a year; most germinate within two years, but seeds can remain in soil for at least seven years.
  • Seeds germinate from mid spring to summer on well-drained soils with little competition from other vegetation.
  • Seeds spread by wind, by attaching to clothing and livestock, on vehicles and farm machinery, and in contaminated seed and fodder; the plant was also accidentally introduced as a garden ornamental and sold under incorrect names.

Control options

  • Do not attempt to treat or dispose of this weed yourself; report it immediately in NSW by calling the NSW Biosecurity Helpline on 1800 680 244.
  • NSW DPIRD, Agriculture and Biosecurity will lead the initial response for treatment and disposal to stop it spreading.

Hygiene and washdown

  • Check clothing, livestock, vehicles and farm machinery for seeds that may be attached before moving between sites.
  • Avoid moving contaminated seed or fodder.
  • 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: Prohibited matter. Report it to Biosecurity Queensland on 13 25 23 within 24 hours and do not move or deal with it. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • Victoria: State prohibited weed. State prohibited weeds are the highest priority: the Victorian Government is responsible for eradicating them, so report any sighting to Agriculture Victoria.
  • South Australia: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • 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: 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: Declared pest, notifiable, prohibited. It is a declared pest throughout the ACT. You must report it to ACT Biosecurity. Dealing with it, such as selling, moving or keeping it, is prohibited.

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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources