The ponds where fringed water lily was found have been removed.
The ponds where fringed water lily was found have been removed.
A pest plant previously eradicated from New Zealand has been found in the Horizons Regional Council area.
Mangaone River Catchment Group and Horizons biosecurity staff recently found ponds infested with a pest water lily in the Mangaone Valley, now the only known location of the plant in New Zealand.
The council worked with the landowner to promptly remove the ponds where the water lily was found.
Horizons biodiversity, biosecurity and partnerships manager Craig Davey said the Mangaone River Catchment Group found the fringed water lily (Nymphoides peltata) as part of routine water testing process using the eDNA sampling method and immediately contacted the council.
“Fringed water lily forms dense mats on the surface of the water which can impede drainage, prevent stock access to drinking water, outcompete native plants for habitat and disrupt recreational activities,” Davey said.
“The plant can reproduce via fragmentation of any root or floating stem, and create new plants via creeping stems. The biggest risk, though, is its small bristled seeds which can be spread by people, machinery, but especially waterfowl.
“While this plant isn’t a designated pest in our Regional Pest Management Plan, we felt it was in the best interest of the community and for biosecurity throughout New Zealand to eradicate this plant, so our team worked quickly to find the actual location and extent of the fringed water lily.”
The pest plant fringed water lily (Nymphoides peltata) was found during routine water testing using the eDNA sampling method.
The plant had been introduced in other parts of the world where it cost millions of dollars to manage, he said.
“In March, we worked alongside leading aquatic pest specialist Dr Paul Champion and landowners to make a control plan for the site to eliminate the risk of the plant spreading further.
“It was easier to take the water away from the plant than it was to take the plant away from the water, and we are confident that fringed water lily is now fully eradicated from the site.”
The last known New Zealand site where the pest was located was at Whangaparāoa. It was eradicated in the early 1990s, raising questions about how it came to be in a stock water pond in the Mangaone Valley, Davey said.
“The notification from the Mangaone River Catchment Group was surprising, but the find does highlight the value of both community groups and landowners exploring what is in their waterways, and how we can work together to help enhance and protect local environments.”
He thanked the Mangaone River Catchment Group, Champion and the landowners for the vital part they played in eliminating the pest plant from the area.
“Work for us has now switched to finding any more sites of the plant, and we need farmers and gardeners to look in any water bodies on their properties to see what’s growing in them, and report anything questionable to Horizons.
“Native to Europe, fringed water lily is a bottom-rooted aquatic plant with long branched stems, yellow flowers with a distinct fringe around the petals, and floating heart-shaped leaves 10-15cm in diameter with a scalloped margin.”
To report sightings of fringed water lily or other pest plants, call Horizons’ pest plant team on 0508 800 800.
