Pest plant previously eradicated from NZ destroyed by Horizons Regional Council

Mangaone River Catchment Group along with Horizons Regional Council biosecurity staff recently found ponds infested with a pest water lily in the Mangaone Valley and this being the only known location in New Zealand.
Horizons Regional Council worked with the landowner to promptly remove the ponds from where the water lily was found.

Horizons biodiversity, biosecurity and partnerships manager Craig Davey says fringed water lily (Nymphoides peltata) was found as part of routine water testing using the eDNA sampling method by the Mangaone River Catchment Group, who then immediately contacted Horizons Regional 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.
“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,” says Mr Davey.
“This plant costs millions of dollars to manage in other parts of the world where it has been introduced, so were presented with a unique opportunity to eradicate the plant from New Zealand before it became more widespread.
“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 site in the country was at Whangaparoa, which was eradicated in the early 1990s, raising questions as to how it came to be in a stock water pond in the Mangaone Valley,” says Mr Davey.
“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.
“We’d like to thank the Mangaone River Catchment Group, Dr Champion and the landowners for the vital part they played in eliminating this pest plant from the area,” says Mr Davey.
“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 - 15 cm in diameter with a scalloped margin,” says Mr Davey.
To report sightings of fringed water lily or any other pest plants, call Horizons pest plant team on freephone 0508 800 800