Salvinia – pray it doesn't come here!


Photograph: Max Finlayson


A bit like Alligator weed, Salvinia is considered one of the nastier aquatic weeds—in fact some people consider it one of the world's worst weeds!


In contrast to Alligator weed, Salvinia is a free-floating fern which forms very thick mats that eventually cover the entire surface area choking the life out of system as light is cut-off and all the species under the mat either have to move away or perish.


Photograph: Max Finlayson


Salvinia is currently found mostly in coastal locations but inland sightings have been recorded, so be alert—you don't want this on or near your farm. Apart from destroying ecosystems it also blocks irrigation pump and channels and deny us opportunities to fish, swim and enjoy our rivers and wetlands.


Of major concern is how hardy Salvinia is. It spreads itself via buds or rhizomes and these can survive and become established in a wide range of environments and water types. It's been reported that Salvinia can survive on mud for up to 12 months and even regenerate after drought, extreme heat or frosts (Management and Rehabilitation of Riparian Lands BMP for the Central West).


While there is a range of control options available it is recommended you seek expert help—Salvinia is a major, major concern and not to be dealt with by landholders on their own.


For more information about Salivinia click here and visit the NSW DPI web site




Keep your eyes out for aquatic weeds


There are a number of weeds that thrive along rivers, on floodplains, and in wetlands, creeks and dams. A number of these have adaptations that allow their seeds or plant fragments to be spread via floodwaters, as well as by vehicles, machinery and animals.


Riverside areas also harbour many paddock weed species and are often a dumping ground for discarded garden plants that become well established and spread down the system.


For NSW farmers we strongly recommend you get a copy of the publication Noxious and environmental weed control handbook—a guide to weed control in non-crop, aquatic and bushland situations, produced by the Department Primary Industries, as it provides important information you need to take into account before launching into weed control.





Alternatively, you can report water weed sightings:

(a) to your local Council's weeds officer, or

(b) the NSW DPI Weeds Hotline on 1800 680244 or email


Further information on water weeds can be found at


Alligator weed infestation - before and after

Photographs: NSW DPI


Alligator weed - it might only be a matter of time!


Photograph: NSW DPI


While Alligator weed will grow on land it is also a major threat to waterways, and if left unchecked completely overgrows and chokes them (see photos).


Of major concern is the potential for Alligator weed to spread via fragments throughout our inland river systems and also that it is resistant to herbicides.


From a farming perspective Alligator weeds seriously threatens irrigation-based industries in particular. It can also dominate pasture areas and stock that eat it can suffer malnutrition, if consumed in large amounts, and photosensitivity-related problems.


While it is most commonly a problem for coastal areas more and more outbreaks are being reported further inland so farmers in particular need to vigilant and immediately report any sightings. An outbreak of Alligator weed has recently been found near Mudgee in NSW.



For more information about Alligator weed click here and visit the NSW DPI web site




Make sure you check your boat!


One of the most common ways aquatic weeds are spread is via recreational boats so be sure you check your boat for plant material at the boat ramp. For further advice click here. Thanks to NSW DPI for allowing use of the image below.