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Giant reed (Arundo donax)

Giant reed forms dense, fast-growing stands that outcompete native plants and reduce food and habitat for native animals. It is highly flammable, can increase fire intensity and frequency, and can alter water flows and block streams.

Key facts

Type: Weed, grass.

Native to: India, Europe, Asia and Madagascar.

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

Other names: Elephant grass.

Best time to act: Treat actively growing plants; flowerheads are present from spring to early winter.

Identification

  • A tall, clumping perennial grass that can grow up to 8 m high.
  • Its green leaves are alternate along the stems and can be up to 100 cm long and 8 cm wide.
  • Stems are woody, usually hollow and up to 4 cm in diameter.
  • Silky, feather-like flowerheads grow in loose clusters at stem ends; they are 30 to 70 cm long and appear from spring to early winter.
  • Look-alike: Native common reed (Phragmites australis) has thinner stems, usually less than 1 cm in diameter, and narrower leaf blades, up to 3.5 cm wide.

Where it grows

In Australia, giant reed occurs throughout the country and is most common around major urban centres, growing in places such as riverbanks, wetlands, drainage lines, parks, gardens and roadsides.

Why it matters

  • Dense stands outcompete native plants and reduce food and habitat for native animals.
  • The plants are very flammable, even when green, and can increase fire intensity and frequency.
  • Tall stems can reach power lines and spark fires.
  • Giant reed can change water flows, block streams and lower groundwater tables.

How it spreads

  • In Australia, it spreads mainly through plant parts: rhizomes and stems with at least one node can grow into new plants.
  • Plant fragments can be productive even when less than 5 cm long, and can spread in moving water, soil or dumped garden waste.
  • Seed is rarely produced, and no viable seed has been found in Australia; if produced, seeds are mostly moved by wind and water.

Control options

  • For small infestations, dig out the plants and remove all rhizomes.
  • For larger stands, remove plants with a bulldozer or tractor, then dig out rhizomes or use registered herbicides to control regrowth.
  • Spray actively growing plants and cover all foliage; cutting plants to ground level and waiting about six weeks before spraying regrowth can be more efficient.
  • For cut-stump treatment, cut stems 5 to 10 cm above the ground and apply registered herbicide to the remaining stems within 15 seconds, following the product label and any permit.

Hygiene and washdown

  • Avoid moving soil or plant fragments from infested sites, as plant parts can spread in soil.
  • Do not dump garden waste containing giant reed; plant fragments can grow into new plants.
  • 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 6 of 11 regions. Regional priority weed in Central Tablelands, Central West, Greater Sydney, Hunter, North Coast, Western. 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: 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
  • 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
  • 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