Aleman grass (Echinochloa polystachya)

Aleman grass grows up to 3 m high in wet and swampy areas. It takes over wetlands and floodplains. It competes with native plants reducing food and habitat for fish and other animals.

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How does this weed affect you?

Aleman grass forms dense stands in wetlands, swampy areas and along banks of watercourses. It:

• outcompetes native plants
• reduces food and habitat for fish, wetland birds and other animals
• can invade crops such as sugarcane and rice
• causes an increase in fire intensity when wetlands dry out
• hosts diseases that affect maize crops
• can poison cattle during drought.

 Livestock health

Aleman grass accumulates large amounts of nitrate in its leaves and stems during drought conditions. Cattle eating high nitrate feeds can get nitrate and/or nitrite poisoning. Avoid grazing Aleman grass until after the drought breaks and the grass is actively growing again.

What does it look like?

Aleman grass is an aquatic or semi-aquatic perennial grass that spreads via runners. It forms dense stands up to 3 m tall.

Leaves are:

• green though sometimes with a reddish tinge
• flat and smooth with an obvious midrib
• 20–60 cm long and 2–3.5 cm wide
• tapered towards the tip and have rough edges
• alternate along the stem. 

Ligule:

Where the leaf blade joins the leaf sheath there is a fringe of stiff yellow hairs up to 4 mm long.

Seedheads:

• are 15–30 cm long
• have many side branches, each 2–11 cm long which, consist of tiny flower spikelets (up to 7 mm long)
• may be present all year round.

Seeds are:

• a grain
• 4–5 mm long.

Stems are:

•  cylindrical with swollen nodes (usually 7-10 per stem)
• up to 1.5 cm in diameter
• coarse and thick in the lower parts
• hairless except for tufts of yellow hairs at the nodes.

 Similar looking plants

Aleman grass looks like the native plant, swamp barnyard grass, Echinochloa telmatophila, which has narrower leaves, less than 18 mm wide. 

Where is it found?

In NSW, most Aleman grass grows on the north coast of NSW. There have been infestations in the Clarence, Richmond, Tweed and Hastings catchments. Many of these infestations were originally planted as ponded pasture for cattle and have ongoing control programs. A few other infestations have been found locations along the east coast of NSW as far south as the South East region.

In the late 1980s, Aleman grass was released into Queensland as a ponded pasture grass for cattle feed. It supplemented other introduced pasture species.

Aleman grass is native to the Americas. Aleman grass is a serious crop weed in India, Mexico and Argentina. In the southern USA, it is a significant weed of rice crops and crayfish production. It is also a weed in Hawaii, Sri Lanka, Chad and Zaire. 

What type of environment does it grow in?

Aleman grass grows best in tropical or subtropical lowlands with high rainfall. It does not tolerate frost or shade.  

It tolerates a wide range of soils but grows best in moderate to highly fertile soils. It tolerates acidic soils and grows in soils with a pH range from 4–8.

Aleman grass grows in wetlands, swampy or seasonally flooded areas and the banks of waterways. Usually it grows in wet soils or water up to 1 m deep but occasionally it’s found in open water up to 2m deep.

Maps and records

• Recorded presence of Aleman grass during property inspections (Map: Biosecurity Information System - Weeds, 2017-2024)
  These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.
  
  

How does it spread?

By seed

Aleman grass does not produce many seeds and is unlikely to spread by seed.

By plant parts

New stems grow from long, rooted runners and from nodes along the stem. Water moves broken stems, runners and roots to new locations. Floods can spread plant parts long distances. Changes in water levels help Aleman grass grow into dense stand that excludes other plants. When water levels drop, plants fall over. New shoots grow from the nodes of decaying stems. Each shoot becomes a new plant which grows as water levels rise.

References

Hannan-Jones M. & Weber J. (2016) Aleman grass Echinochloa polystachya—Pest plant risk assessment, State of Queensland.

Hosking J.R., Sainty G.R., Jacobs S.W.L. & Dellow J.J. (in prep), The Australian WeedBOOK.

Identic Pty Ltd. and Lucid central  (2016). Weeds of Australia Fact sheet: Echinochloa polystachya (Kunth) Hitchc. Retrieved 19 October 2022 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/echinochloa_polystachya.htm

Northern Territotry Department of Primary Industry and Resources. (2019). Agnote No:E53 Aleman Grass. Retrieved  3 July 2023 from https://industry.nt.gov.au/__data/assets/pdf_file/0005/233366/642.pdf

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 22 October 2021 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Echinochloa~polystachya

More information

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Control

Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.

Contact your local council weeds officer for help with identification, control and disposal.

Physical removal

Young plants can be dug out, when the soil is not waterlogged. Collect and dispose of all plant fragments. Mature plants are difficult to remove by hand.

Grazing

Aleman grass is very palatable and livestock (including cattle and horses) will eat aleman grass down to the crown during dry conditions. Grazing can suppress growth, especially if plants are grazed low enough so that leaves are all submerged when water levels rise.

Spot spraying

Spray actively growing plants to the point of run off. 

 

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: Up to 200 mL in 10 L of water
Comments: Spot spray application.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
North Coast	Regional Recommended Measure* (for Regional Priority - Eradication) Land managers should mitigate the risk of the plant being introduced to their land. Land managers should eradicate the plant from the land and keep the land free of the plant. A person should not deal with the plant, where dealings include but are not limited to buying, selling, growing, moving, carrying or releasing the plant. Notify local control authority if found.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2023