Precision is everything on Lake Benmore's islands, where carefully targeted work is underway to protect one of New Zealand's rarest native plants from the spread of introduced pines.
Toitū Te Whenua Land Information New Zealand is leading high-precision control work to tackle wilding pines on the islands, while leaving the critically endangered native whip broom untouched.
An aerial image showing where control work has been occurring. The pink dot indicates a known whip broom plant, and the blue circle indicates the 10-metre halo which has been cleared around it. Image courtesy of Boffa Miskell
Toitū Te Whenua Leader Biosecurity Tracey Burton says Benmore's islands have become an important refuge for the plant.
"When Lake Benmore was created in the 1960s, former ridges and high points in the land became islands, unintentionally protecting areas of dry, rocky habitat from grazing animals like possums and deer.
"This isolation has helped plants like the whip broom to survive in a tough environment. Today, however, those same island habitats are under increasing pressure from introduced pines which can quickly change light levels, soil moisture and space, crowding out native plants.
"Toitū Te Whenua contractors Boffa Miskell are carrying out the control work with a strong focus on accuracy. Pines are first removed in a careful 10-metre 'halo' around each whip broom plant to reduce immediate pressure, with future work involving the precise application of herbicide to remaining trees.
"This kind of work must be done with real care. A small mistake can have a big impact when you're working around plants that are already on the brink," Burton says.
LINZ Crown Property Leaders Lee Farnhill and Tracey Burton stand within one of the cleared “halo” zones around whip broom plants on Black Jack Island, Lake Benmore. A whip broom plant can be seen in the foreground. Pines to be controlled in future work are in the background.
During Conservation Week (20 to 26 April 2026), Toitū Te Whenua is also taking the opportunity to shine a light on the whip broom itself.
"It doesn't look like much at first glance, and it's easy to overlook," Burton says.
"But this modest little plant produces delicate flowers and plays an important role in these unique ecosystems. Its rarity makes it ecologically precious."
A close-up of the whip broom’s small purple flowers in bloom. Image courtesy of Boffa Miskell
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