Weed of the Week: Amazon Frogbit

Published on 26 December 2022

Welcome to Weed of the Week, a series of articles where we give you the information you need to protect your property and our region from the Snowy Monaro’s priority weeds.

This week we’re looking at an insidious water weed often spread throughout NSW via illegal online trade: Amazon Frogbit.

Snowy Monaro Regional Council is calling on all community members to get to know the weed species that can impact our region. By knowing what to look for, we can all do our part to protect our environment, help our farmers and support our community.

The impact of weeds on our community can be devastating and is estimated to cost the NSW economy about $1.8 billion annually (NSW Department of Industry, 2018).

What is Amazon Frogbit?

Amazon Frogbit (Limnobium laevigatum) is a water weed that grows in fresh water. It forms thick mats of small round bright green leaves, growing quickly across bodies of fresh water.

It is Prohibited Matter in NSW and must be reported upon sight. It is prohibited from being sold, traded or possessed by anyone for any reason.

Where is Amazon Frogbit found?

Amazon Frogbit grows readily in any body of fresh water – flowing like creeks and rivers, and non-flowing like ponds, lakes and dams. It can grow in direct sunlight, full shade, and a wide range of water temperatures and pH levels – even tolerating slightly salty water.

Amazon Frogbit has been found across NSW as a result of illegal online trading, including in the South East. Shops and markets have been found selling Amazon Frogbit as an aquarium addition and decorative plant.

While all known infestations have been controlled and eliminated, the extremely invasive nature of this weed means that there are further infestations still to be found and further spread into the environment is likely.

Why is Amazon Frogbit a problem?

Amazon Frogbit grows quickly, floating on the surface of fresh water to form a contiguous covering across the body it has infested – readily blocking natural and man-made waterways and channels.

This kills off and prevents the regrowth of native water plants and robs aquatic life of light, food and shelter.

If allowed to become established it will prevent productive and recreational use of waterways and it will deoxygenate potable water supplies as it dies off, resulting in significant control and remediation costs.

Seeds remain viable for years, and both seeds and seedlings can be carried by water flow and aquatic or semi-aquatic animals to spread infestations to new locations.

As it is sold through unwitting or unscrupulous suppliers, the illegal dumping of decorative aquarium plants sees new or renewed infestations occur.

What do you do if you detect Amazon Frogbit?

Amazon Frogbit, like other Prohibited Matter weeds in NSW, must be immediately reported if sighted, discovered or suspected.

Do not attempt to destroy or control Amazon Frogbit on your own. If you find, or suspect that you have found this weed on your property, in public, or anywhere else in our region – call Council on 1300 345 345 or the NSW Biosecurity Helpline on 1800 680 244 immediately.

Council, NSW Department of Primary Industries and other partner agencies will initiate an immediate emergency response program at no cost to the landowner.

Eliminating weed infestations in their early stages of invasion provides significantly greater return on investment than trying to manage it once established.

What can you do?

• Learn to identify Amazon Frogbit and seek immediate advice if you suspect you’ve found it growing on your property or in a body of water in our region.
• Only buy identifiable aquarium and aquatic plants from trusted vendors.
• Contact Council’s Biosecurity officers if you suspect the presence of Amazon Frogbit. Our staff provide a free, onsite weed identification and advisory service.

Download the free NSW WeedWise app for detailed information on how to identify and manage local priority weeds. Visit www.dpi.nsw.gov.au/biosecurity/weeds

Visit Council’s website to understand how we can help you with weed management.  www.snowymonaro.nsw.gov.au/Environment-Waste-and-Weeds/Biosecurity-and-Weeds

Visit the Department of Primary Industries (DPI) website for information on weed control methods – www.dpi.nsw.gov.au/biosecurity/weeds/weed-control

Contact Snowy Monaro Regional Council if you have any questions regarding weeds on your property or in your neighbourhood. Call 1300 345 345 to be connected to our Biosecurity Officers who specialise in weed management.

The information for this article was sourced from the NSW Department of Primary Industries WeedWise portal.