Aleman grass (Echinochloa polystachya)

Aleman grass is an aquatic or semi-aquatic perennial grass. It forms dense stands in swampy areas and along banks of watercourses and is able to grow in water 2 metres deep.

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How does this weed affect you?

Aleman grass is an aquatic or semi-aquatic perennial grass. It forms dense stands in swampy areas and along banks of watercourses. Aleman grass will quickly replace native aquatic species, forming a monoculture. It is a serious threat to the wetland and floodplains areas of tropical Australia. Large areas of open water are also at risk of invasion, potentially impacting on fisheries and waterbird habitat.

Aleman grass is capable of invading crops such as sugar cane and rice. It may also cause nitrate or nitrite poisoning in grazing cattle following drought—due to the large amounts of nitrogen it accumulates.

First released into Queensland in the late 1980s as a ponded pasture species for cattle production, aleman grass was used to supplement other introduced pasture species.

Where is it found?

Aleman grass is native to the Americas, from southern USA and Mexico through to Argentina and Uruguay. It is one of the most frequently occurring grasses on the Amazon floodplains, where it is an important fodder for cattle.

Aleman grass has been recognised as a serious crop weed in India, Mexico and Argentina. In southern USA, it is a significant weed of rice crops and crayfish production. It is also considered a weed in Hawaii, Sri Lanka, Chad and Zaire.

In Australia, infestations have occurred in Queensland, the Northern Territory, Western Australia and northern New South Wales (NSW), where aleman grass has invaded seasonally flooded areas, swamps and the banks of watercourses.

There have been approximately 20 known infestations of aleman grass in the Richmond and Tweed catchments of northern NSW. All infestations are subject to ongoing control programs.

How does it spread?

Aleman grass spreads vegetatively when broken stems, runners and roots are moved in water. A single flood event has the potential to spread it a considerable distance.

Growth and localised spread of aleman grass depends on fluctuating water levels. When water levels drop, plants fall over and new shoots are produced from the nodes of decaying stems. Each new shoot then produces an individual plant which continues to grow as water levels rise. Shoots can grow from any node. Seed production of aleman grass is poor and it is unlikely to spread in this way.

What does it look like?

Lower parts of the stems of Aleman grass are coarse and thick arising from long, rooted runners. Plants can grow to 2.5 metres in height.

Leaves are flat and smooth, tapered, 2–5cm long and 2–3.5 cm wide, with rough edges.

The ligule (the area surrounding the leaf base) is a fringe of stiff yellow hairs up to 4 mm long.

Flower heads are a branched spike 15–30 cm long. Numerous branches occur along the seed head and are 2–11 cm long.

Aleman grass flowers during summer.

Habitat

Aleman grass will grow in swampy areas and along banks of watercourses, as well as in large areas of open water, up to 2 metres deep.

Acknowledgements

Reviewed by: Rod Ensbey  

Edited by: Elissa van Oosterhout

References

Hannan-Jones M & Weber J (2008) Aleman grass  Echinochloa polystachya—Pest plant risk assessment, Queensland Government—Department of Primary Industries and Fisheries, Brisbane.

Hosking JR, Sainty GR, Jacobs SWL & Dellow JJ (in prep), The Australian WeedBOOK.

Jacobs, SWL, Whalley, RDB and Wheeler, DJB (2014). Echinochloa polystachya, in PlantNET - The Plant Information Network System of The Royal Botanic Gardens and Domain Trust, Sydney, Australia. Available at http://plantnet.rbgsyd.nsw.gov.au

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Control

A local council weeds officer will assist with identification, control information, removal and eradication. Aleman grass is capable of spreading from plant fragments and requires strict hygiene procedures during its removal.

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


PERMIT 9907 Expires 31/03/2020
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: M, Inhibitors of EPSP synthase
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 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*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
North West Regional Recommended Measure*
Land managers should mitigate the risk of new weeds being introduced to their land. The plant should be eradicated from the land and the land kept free of the plant. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfill the general biosecurity duty for this weed click here

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Reviewed 2017