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Aleman grass (Echinochloa polystachya)

Aleman grass was released in Queensland in the late 1980s as ponded pasture for cattle. In NSW it forms dense stands in wetlands and floodplains, where it competes with native plants and reduces food and habitat for wildlife.

Key facts

Type: Weed, aquatic.

Native to: The Americas.

Established in: QLD, NSW, NT.

Best time to act: Treat plants when they are actively growing.

Identification

  • This aquatic or semi-aquatic perennial grass spreads by runners and can form dense stands up to 3 m tall.
  • Its green leaves, sometimes with a reddish tinge, are flat, smooth and 20–60 cm long by 2–3.5 cm wide.
  • A fringe of stiff yellow hairs, up to 4 mm long, occurs where the leaf blade joins the sheath.
  • Seedheads are 15–30 cm long with many side branches and may be present all year.
  • Stems are cylindrical, up to 1.5 cm in diameter, and usually have 7–10 swollen nodes.
  • Look-alike: It resembles native swamp barnyard grass (Echinochloa telmatophila), which has narrower leaves, less than 18 mm wide.

Where it grows

In NSW it is found mostly on the north coast, including infestations in the Clarence, Richmond, Tweed and Hastings catchments, in wetlands, swampy or seasonally flooded areas and along waterways.

Why it matters

  • Dense stands outcompete native plants and reduce food and habitat for fish, wetland birds and other animals.
  • It can invade sugarcane and rice crops, increase fire intensity when wetlands dry out, and host diseases that affect maize crops.
  • During drought, it can accumulate nitrate in its leaves and stems and poison cattle that eat it.

How it spreads

  • It produces few seeds and is unlikely to spread by seed.
  • New stems grow from rooted runners and nodes along stems; water can carry broken stems, runners and roots to new locations, and floods can spread plant parts long distances.
  • When water levels drop, stems can fall over and produce new shoots from nodes as they decay; these shoots grow into new plants when water levels rise.

Control options

  • Follow up after initial control by checking for and removing regrowth or new seedlings; combining control methods is usually more successful.
  • Young plants can be dug out when soil is not waterlogged, and all plant fragments should be collected and disposed of; mature plants are difficult to remove by hand.
  • Grazing can suppress growth, but avoid grazing during drought until the drought breaks and the grass is actively growing again because it can contain high nitrate levels.
  • Spot-spray actively growing plants using registered herbicides approved for aquatic use, and contact the local council weeds officer for advice.

Hygiene and washdown

  • Collect and dispose of plant fragments, as broken stems, runners and roots can be carried by water to new locations.
  • 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 North Coast. 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: 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