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Spiny rush (Juncus acutus)

Spiny Rush forms dense, persistent stands that can out-compete other plants and become the dominant vegetation cover in agricultural and natural areas. Its sharp points can injure people and animals, while dense thickets can obstruct access and water flow.

Key facts

Type: Weed, herb.

Native to: Thought to be native to the Mediterranean region, western Europe, western North America, South America, Asia and southern Africa..

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

Other names: Sharp Rush, Sharp-pointed Rush, Cultivation Rush.

Best time to act: It can flower and germinate at any time of year, but flowers mainly in spring and summer and ripe fruit can be present virtually all year.

Identification

  • It forms a tough, dense, hemispherical tussock with a very short rhizome.
  • Its blue-green to dark-green stems and leaves are round in cross-section and end in very sharp, stiff points.
  • The stems and leaves have continuous pith, visible in cross-section.
  • Small greenish, brown or reddish-brown flowers grow in dense clusters.
  • Its shiny brown capsules are visible above tepals that cover only the lower half; each capsule contains many small seeds.
  • Look-alike: The native Juncus kraussii has narrower, erect clumps rather than Spiny Rush’s robust hemispherical tussocks, and its seed capsules are covered by the tepals.
  • Look-alike: Native Juncus polyanthemus and Juncus usitatus have leaf blades reduced to a tiny point on the leaf sheath, unlike Spiny Rush’s long leaf blades.

Where it grows

In Australia it occurs in southern states and territories, along the New South Wales coast into south-east Queensland, and around Alice Springs, particularly in damp or brackish areas such as wetlands, waterways, pastures and disturbed sites.

Why it matters

  • It competes with pasture plants and is not readily eaten by grazing animals, so it can dominate pasture.
  • Dense stands can obstruct drains and channels, impede water flow and cause flooding, and can prevent livestock from accessing water.
  • Its sharp points can seriously injure people and animals, and dense thickets can make areas difficult to access.
  • It can cover large areas and exclude other vegetation, including in natural ecosystems.

How it spreads

  • It spreads mostly by abundant seeds carried by moving water, particularly along waterways.
  • Seeds can also be spread by machinery, birds, stock and other animals; short rhizomes can travel in soil attached to vehicles or animals.

Control options

  • Control infestations early, as Spiny Rush is very difficult to eradicate once established.
  • Small stands can be dug out; sever the roots, and burn the top growth if seed is present.
  • For dense infestations, machinery can cut plants just below ground level; removed plants can be heaped and burnt, followed by cultivation to encourage seedlings.
  • Follow-up cultivation over the next two summers is needed to destroy seedlings, and follow-up for 2–4 years is advised; check current registered herbicides, as chemical control is often used with other measures and may be impractical in dense patches.

Hygiene and washdown

  • Avoid moving soil from infested sites on vehicles or machinery, as seeds and short rhizomes can be transported in soil.
  • Take care not to carry seeds or soil along waterways or to uninfested sites on machinery.
  • 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: Regional priority in 1 of 11 regions. Regional priority weed in Hunter. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Regionally controlled / restricted weed (varies by region). Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • 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
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources