A dense stand of invasive Taiwanese Cherry trees has gone unchecked on Whangarei District Council owned and managed land around its sewage treatment station. Photo / Christine Stephenson
A dense stand of invasive Taiwanese Cherry trees has gone unchecked on Whangarei District Council owned and managed land around its sewage treatment station. Photo / Christine Stephenson
People concerned about the rapid spread of Taiwan cherry trees around Whangārei’s sewage treatment plant are unlikely to see them removed any time soon, as authorities say the law doesn’t require it.
However, a law professor says the authorities have it wrong.
The trees (Prunus campanulata), known fortheir vibrant pink blossoms, are listed as an invasive pest across New Zealand, including on Northland Regional Council’s (NRC) website.
A Northern Advocate reader, who asked not to be named, said the Whangārei District Council (WDC), which owns the Kioreroa Rd treatment plant site, should remove the unchecked trees as they pose a serious ecological threat to the wider landscape.
“In another 10 years, it will be everywhere,” the man said, pointing to a photo that showed a dense stand of the trees around the facility.
He believed the WDC was setting a poor example by allowing the proliferation.
Tui love the nectar and berries of Taiwan cherry trees, but they are crowding out native plant species. Photo / NZME
WDC wastewater manager Simon Charles said the council would not remove the trees unless required to by NRC - the region’s pest management enforcer - to do so.
Charles and NRC’s biosecurity manager, pest plants Joanna Barr each said the trees were not in breach of the relevant legislation - sections 52 and 53 of the Biosecurity Act 1993, which state:
No person shall knowingly communicate, cause to be communicated, release, or cause to be released, or otherwise spread any pest or unwanted organism except—
(a) in the course of and in accordance with a pest management plan; or
(b) as provided in an emergency regulation made under section 150; or
(c) for a scientific purpose carried out with the authority of the Minister; or
(d) as permitted either generally or specifically by a chief technical officer.
(53) Duties of owners of organisms
(1) Owners or persons in charge of an organism which that person knows or suspects constitutes, contains, or harbours a pest or unwanted organism must not—
(a) cause or permit that organism to be in a place where organisms are offered for sale or are exhibited; or
(c) propagate, breed, or multiply the pest or unwanted organism or otherwise act in such a manner as is likely to encourage or cause the propagation, breeding, or multiplication of the pest or unwanted organism.
Barr said while the statutory obligations of any person under Sections 52 and 53 of the Biosecurity Act 1993 do apply to Taiwan cherry in Northland it was council’s understanding from the Ministry of Primary Industries that the sections do not apply to natural spread from weeds on a person’s property.
“They relate to deliberate actions such as propagating for sale, or planting.”
Biosecurity New Zealand director of pest management John Walsh said MPI could not confirm whether a breach of the Biosecurity Act has occurred in any specific case without further information and a proper investigation.
“However, in general, our view is that simply having a pest plant on your land, which then spreads naturally, is not a breach of sections 52 or 53 of the Act.
“Neither section applies to natural activity. There must be a deliberate action by a person to cause or encourage the spread or multiplication of a pest.”
Auckland University professor of law Mark Henaghan said section 52 covers owners, which the council are because the pest is on its land, and it can be argued that they are otherwise causing the spread of it.
Section 53 applied because the council is in charge of the pest and by not containing it they are “acting in a manner which is likely to cause the propagation etc of it,” he said.
Barr said NRC would love to see weed management on public land provide a good example to other landowners, and back up the “great work” communities doing tackling pests like Taiwan cherry.
She acknowledged weeds were a major challenge for Northland landowners and that councils had competing priorities.
The trees, native to East Asia, were introduced to New Zealand as an ornamental plant in the 1960s but have since been classified as a pest plant because of their aggressive spread and ecological impact.
The Department of Conservation included Taiwan cherry in its 2024 list of 385 “environmental weeds”.
Birds spread Taiwan cherry seeds in their droppings after feasting on nectar from the blossoms that last a couple of weeks, and later on the berries.
Fans of the trees claim they provide a valuable food source for the native birds, especially tūī, but opponents argue it’s an unsustainable, short-term sugar spike at a time of scarcity, potentially harming bird populations long term and that once established, the trees form dense stands that crowd out native nectar producers such as pōhutukawa, flax, kōwhai, and ngaio.
Sarah Curtis is a news reporter for the Northern Advocate, focusing on a wide range of issues. She has nearly 20 years’ experience in journalism, most of which she spent court reporting in Gisborne and on the East Coast
