Lagarosiphon is a water weed that forms dense mats under or at the water surface. It reduces food and habitat for fish and other aquatic animals.
Lagarosiphon forms dense mats that can be several metres thick. It:
Lagarosiphon is a perennial plant that grows underwater. It can be attached to the sediment in the waterway and be fully submerged or free floating.
Only female flowers have been found outside its native range. In its native range, lagarosiphon produces male flowers that break off and float to the surface.
The main difference between Lagarosiphon and similar looking plants is that Lagarosiphon leaves spiral up the stem. The other plants have leaves that are clustered in groups around the stem. Similar looking plants include:
There are currently no naturalised infestations in Australia. However lagarosiphon is sometimes planted in aquariums. During the late 1970s, it was found and eradicated from a few small dams near Melbourne and Newcastle. These infestations may have originated from ornamental plants in aquariums or ponds. All infestations have been eradicated.
Lagarosiphon is native to southern Africa.
It is a major water weed in parts of Europe and New Zealand.
Lagarosiphon grows in high mountain streams and ponds. It prefers:
Lagarosiphon can grow in:
Lagarosiphon is not known to produce male flowers, fruit or seed in Australia (or anywhere else outside its native range).
Plant fragments break off and new roots grow from the nodes on the stem. Water and boats spread the fragments and it can move large distances downstream. Infestations are often first recorded at boat ramps.
CRC for Australian Weed Management (2003). Weed management guide: Lagarosiphon major.
Matthews, J., Beringen, R., Collas, F. P. L., Koopman, K. R., Odé, B., Pot, R., ... & Leuven, R. S. E. W. (2012). Knowledge document for risk analysis of the non-native Curly Waterweed (Lagarosiphon major) in the Netherlands. Retrieved 3/08/2020 from: https://repository.ubn.ru.nl/bitstream/handle/2066/103462/103462.pdf
PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 3/08/2020 from:http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Lagarosiphon~major
Sainty, G. R., & Jacobs, S. W. (2003). Waterplants in Australia (No. Ed. 4). Sainty and Associates Pty Ltd.
Please do not attempt to treat or dispose of this weed yourself. Report this plant if you see it anywhere in NSW by calling the helpline listed at the top of this page immediately.
NSW DPI will lead an initial response for the treatment and disposal of the plant to stop it from spreading
See Using herbicides for more information.
Diquat 200 g/L
Rate: 5 L per megalitre water
Comments: Apply by stem injection below the surface or as a surface spray
Withholding period: Do not use treated water for human consumption, livestock watering or irrigation purposes for 10 days after application. Do not graze or cut sprayed vegetation for stock food for 1 day after application. See label for harvest withholding periods.
Herbicide group: 22 (previously group L), Inhibition of photosynthesis at photosystem I via electron diversion (PSI electron diversion)
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.
|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
A person who deals with prohibited matter or a carrier of prohibited matter is guilty of an offence. A person who becomes aware of or suspects the presence of prohibited matter must immediately notify the Department of Primary Industries