Hymenachne is a tall perennial semi-aquatic grass. It can outcompete native plants and reduce numbers of fish and other aquatic animals.
This plant is a Weed of National Significance
This plant is a water weed
This plant must not be sold anywhere in NSW
Hymenachne forms dense infestations which:
Hymenachne is a perennial grass that can be up to 3.5 m tall. It can grow upright or semi-upright on land or float in water.
Roots are produced from the nodes on the horizontal stems.
There are small, isolated infestations in the Richmond, Tweed and Clarence River catchments on the North Coast of NSW. All known infestations have control programs to eradicate them.
Hymenachne is native to the South and Central American tropics. Hymenachne was introduced to QLD and the NT as fodder for cattle in ponded pastures. It has since escaped cultivation and become a weed. If left undetected, hymenachne has the potential to spread further in northern NSW and become a major weed of wetlands and waterways.
Hymenachne grows in tropical and subtropical climates. It prefers nutrient-rich freshwater in swampy or seasonally flooded areas. It grows in wetlands, floodplains, irrigation channels, sugarcane crops and on stream banks. Hymenachne can grow in water up to 2 meters deep.
The cultivar named 'Olive' can grow in the tropics and warm temperate areas.
Hymenachne reproduces by seed and broken stem fragments.
Each flower head can produce over 4000 seeds. Seeds can remain viable in the seed bank for 8 years. They need contact with damp soil for at least 48 hours before germinating. Seeds spread:
Plants can grow from broken stem fragments. Floodwaters move stem fragments to new locations. The fragments take root in damp soil.
Charleston, K. (2006). Hymenachne (Hymenachne amplexicaulis) Control methods and case studies, Queensland Department of Natural Resources, Mines and Water.
PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved July 2021 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Hymenachne~amplexicaulis
Sainty, G. R., & Jacobs, S. W. (2003). Waterplants in Australia (No. Ed. 4). Sainty and Associates Pty Ltd.
Wearne, L. J., Clarkson, J., Grice, A. C., van Klinken, R. D., & Vitelli, J. S. (2010). The Biology of Australian Weeds 56.'Hymenachne amplexicaulis'(Rudge) Nees. Plant Protection Quarterly, 25(4), 146-161.
Hymenachne is difficult to control and requires hygiene procedures during its removal.
If you suspect you have found hymenachne contact a local council weeds officer who will assist with identification, removal and eradication.
See Using herbicides for more information.
PERMIT 86806 Expires 31/12/2023
Haloxyfop 520 g/L
(Only products registered for aquatic use)
Rate: 50 mL product / 100 L OR 50 mL product / 100 L OR up to 770 mL product / ha (up to a max water volume of 1540 L/ha)
Comments: Apply as a foliar spray. Add adjuvant (114 g/L Alkyethoxyphosphate) 200 mL product / 100 L. This permit is limited to persons who are employed, directed or contracted by a Local Control Authority in NSW.
Withholding period: Do NOT graze or cut for stock food for 7 - 28 days after application. See label for more details.
Herbicide group: 1 (previously group A), Inhibition of acetyl co-enzyme A carboxylase (ACC'ase Inhibitors)
Resistance risk: High
PERMIT 13921 Expires 31/03/2027
Glyphosate 360 g/L
(Only products registered for aquatic use)
Rate: 14 L / hectare
Comments: Apply by boom, handgun or knapsack, a maximum of 4 times a year. Refer to permit for further comments.
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
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. |
All of NSW |
Prohibition on certain dealings
Must not be imported into the state, sold, bartered, exchanged or offered for sale. |
Greater Sydney |
Regional Recommended Measure* (for Regional Priority - Prevention)
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. |
Hunter |
Regional Recommended Measure* (for Regional Priority - Prevention)
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. |
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. |
North West |
Regional Recommended Measure* (for Regional Priority - Prevention)
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 |
Reviewed 2023