Dangerous Australian imposters are causing problems at Waikanae Estuary.

Dangerous Australian imposters are causing problems at Waikanae Estuary. Posing as New Zealand natives, a bunch of Tasmanian troublemakers are squeezing out the locals, forcing local government agencies to take decisive action.

“We have to act now before they take over,” said Kāpiti Coast District Council’s biodiversity adviser Rob Cross. “The older ones are already breeding.”

Tasmanian boobialla trees look a lot like the native ngaio, so much so that nurseries have supplied them as such, and some were planted on reserve land on the northern side of the Waikanae Estuary.

Worse Identifying Aussie invaders

Greater Wellington’s Michael Urlich (standing, left), Kāpiti Coast District Council’s Rob Cross and DoC ranger Eric Stone unite to fight Tasmanian boobialla at Waikanae Estuary.

Worse still, boobialla hybridizes with ngaio, threatening the future of one of the district’s most important coastal trees.

“Local ngaio trees have a unique genetic identity that could be lost because of boobialla,” Mr Cross said. “The character of local ngaio is part of our natural heritage.”

His sentiments are echoed by Greater Wellington Regional Council biosecurity officer Michael Urlich and Department of Conservation ranger Eric Stone, who met Rob at the estuary to discuss tackling weed problems in and around DoC’s scientific reserve.

“Unless we control boobialla we will end up with nothing but hybrid fakes instead of the real thing,” said Michael.

Eric said that weed control would feature prominently in a new estuary restoration plan being prepared for DoC, local and regional councils and the Waikanae Estuary Care Group.

“We will be continuing our strategic approach to the estuary’s serious weed problems,” said Eric. “Boobialla is not yet chronic, so it is a good one to nip in the bud.”

Contractors will soon remove a row of large boobialla beside the river to the south of the Waimanu Lagoons. The Waikanae Estuary Care Group will replant the gaps with native estuarine plant species.

Boobialla can be identified by its green growing tips and the lack of large glands on its leaves. Ngaio has dark brown or black growing tips, and large glands on its leaves.