Southlanders may unwittingly be growing a noxious pest in their backyards

Southlanders may unwittingly be growing a noxious pest in their backyard, thinking it’s an attractive ornamental plant.

Purple loosestrife grows up to two metres tall, has woody stems with narrow leaves and produces long spiked of purple flowers, followed by black seed capsules from December to February.

But it is classified as an eradication species under the Regional Pest Management Plan for Southland, meaning all plants must be destroyed within the Southland boundary, Environment Southland biosecurity and biodiversity operations manager Ali Meade said.

“We understand that people can feel attached to these plants in their gardens, so we approach each situation with sensitivity, while also explaining the rules and the issues that purple loosestrife can create,’’ she said.

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In 2017, when Environment Southland biosecurity officers visited a property that was often used as a wedding venue, and provided it with advice that the plant needed to be removed.

The venue had planted purple loosestrife many years ago, unaware that it was a pest plant, Meade said.

“The property owners were upset as these plants were part of their garden, but they subsequently controlled the plants with herbicide,’’ she said.

The plant needs to be removed because it rapidly invades damp ground and shallow water, outcompeting native species, is long-lived, and produces millions of seeds.

”The large stands destroy wetland and marginal habitats, causing blockages and can aid in flooding. The destruction of these habitats reduces the food sources for fish and can displace native nesting birds.’’

Seeds can remain viable submerged in water for up to two years.

Environment Southland has recently run a campaign about the plant.

The agenda for a full council meeting, to be held on Wednesday, says multiple new sites are being reported by members of the public.

Staff had also been made aware of plant swapping between garden networks and friends, which would be followed up by the biosecurity team.

Meade said specialised control methods were required to manage purple loosestrife and would be carried out free of charge by an Environment Southland biosecurity officer or approved contractor.

If people see purple loosestrife or have some in their garden, please get in touch with Environment Southland’s pest plant team or visit the Pest Hub website: www.pesthub.es.govt.nz”