Decisive action under the NSW Government's New Weed Incursion Plan has prevented the spread of an invasive water weed, with NSW biosecurity officers intercepting and seizing yellow burrhead (Limnocharis flava) plants in the Illawarra this March.
NSW Department of Primary Industries and Regional Development (DPIRD) Chief Invasive Species Officer, Scott Charlton, said this is the first time mature yellow burrhead plants have been found in NSW.
"The successful detection highlights the strength of NSW's proactive and strategic approach under the New Weed Incursion Plan and NSW Invasive Species Plan to exclude, eradicate and contain new invasive weed species before they pose a threat to agriculture, our environment, economy and communities," Mr Charlton said.
"Showcasing biosecurity detective work at its best, the combined efforts of on-ground inspections, market surveillance, community reporting, online intelligence monitoring, scientific verification and forensic DNA tracing are now helping to intercept and destroy this damaging weed before it can establish here."
DPIRD is leading a strategic response with Local Control Authorities (LCA) and Botanic Gardens of Sydney, through the Queensland Department of Primary Industries led National Response Program (National Tropical Weeds Eradication Program), to track down and destroy the unwanted weed.
Online intelligence monitoring by biosecurity officers in Queensland first alerted NSW DPIRD in late 2022 to the possibility the weed was being illegally sold in Lismore, Newcastle and Shellharbour.
DPIRD identified four suspected incursion sites, which have been inspected and monitored by the relevant LCAs, supported by the NSW Weeds Action Plan.
This March, diligent detective work by the Illawarra Shoalhaven Joint Organisation's Illawarra District Weeds Authority, uncovered two yellow burrhead plants in a Shellharbour backyard.
Identification of the weed was confirmed by the Botanic Gardens of Sydney's National Herbarium of New South Wales.
Community intelligence has indicated a Sydney street market as the potential source of the seized yellow burrhead plants.
NSW DPIRD has proactively developed an environmental DNA (eDNA) assay or marker, which will support on-ground surveillance to detect the presence of yellow burrhead from water samples at markets and in the environment.
Yellow burrhead is Prohibited Matter under the NSW Biosecurity Act 2015 and it is illegal to possess, sell or knowingly distribute the plant in NSW due to its severe environmental and agricultural risks.
With a national eradication program in place for northern Australian infestations, yellow burrhead has the potential to invade northern NSW.
Recognised introduction pathways include seed spread by water and cultivation of yellow burrhead as an ornamental plant or vegetable by people, who may not be aware the plant is a serious weed.
Native to Central and South America, yellow burrhead has naturalised across India and south-east Asia, and is a major weed in Malaysia, Sri Lanka and Indonesia where it invades wetlands, rice fields, and irrigation channels.
The weed outcompetes native aquatic plants, reduces food and habitat for fish and aquatic animals, causes silt build-up in waterways, slows or blocks water flow in natural waterways, agricultural channels and drains, restricts access to the water for people and animals, and creates mosquito habitats.
Information about yellow burrhead, including 3D digital models to help you recognise the weed, is available from NSW WeedWise.
DPIRD will continue surveillance for yellow burrhead and encourages the community to report any suspected yellow burrhead sightings to the NSW Biosecurity Helpline on 1800 680 244.
