Weeds of National Significance found thriving in suburban pond
On Friday 10 January 2025, the Weed Management Branch (WMB) was alerted by a member of the public that Cabomba caroliniana was being advertised for sale on Facebook marketplace by a private resident in Millner.
Cabomba is a Class A declared weed in the Northern Territory (NT), which means it must be eradicated. After many years and millions of dollars spent, cabomba was successfully eradicated from an NT waterway, with monitoring still ongoing. The WMB initiated a same-day response to the advertisement, safely and swiftly seizing and destroying the cabomba plants.
At the property, a holding pond with 5 prepared strands of cabomba sat ready for the public to select their preferred purchases, all approximately 50 cm long and in full flower.
The seller advised of a second pond located in another area of the yard that contained the parent cabomba plants, which had apparently been growing there for many years. Upon viewing this pond, the WMB Officers were surprised to also find Sagittaria platyphylla, Salvinia molesta, Opuntia Opuntia ficus-indica and Pistia stratiotes, all of which are nationally listed as WoNS.
The seller advised that despite growing the cabomba for more than 2 decades, they were unaware it was a weed. WMB Officers emptied and cleaned the entire pond to remove all plant material and substrate. Specimens were submitted to the NT Herbarium for final identification and confirmed as first identified.
During pond cleaning, water was filtered through a fine-mesh sieve to ensure no material escaped. The pond was emptied, scrubbed clean of all algae and other material and left in a state ready for the owner to start again with new plants which are not declared weeds and are safe for the environment. Efforts were made through the whole process to protect the fish and snails in the pond and relocate them to other ponds on the property.
This site will now become the subject of ongoing inspections until WMB Officers are satisfied that no further germination from seed or plant matter occurs.
This case highlights the critical role that citizen science plays in having “eyes in the community”. The initial report led to swift removal of these dangerous weeds from public circulation.
