Myrtle rust outside Whitianga office

Myrtle rust was first discovered in New Zealand last year. PHOTO / MPI

An airborne fungal disease that threatens the iconic Pohutukawa and other trees in its family has been detected on a tree outside council offices in Whitianga.

Myrtle rust is a fungal disease that attacks plants in the myrtle family — everything from pohutukawa, rata and manuka, to feijoa and eucalyptus, monkey apples and bottlebrush — causing deformed leaves, leaf loss, damaged fruits, canopy dieback, stunted plant growth, and eventually plant death.

Hopes of containing it have disappeared and the Government's response has shifted as it has become widespread in the North Island and now appeared in the upper South Island.

"We now have well over 540 infected sites across the North Island and now the top of the South," says MPI's myrtle rust response spokesperson Dr Catherine Duthie. "Because of the windborne, pernicious nature of the disease, we have to anticipate that there are likely to be many more infected sites beyond these."

Thames-Coromandel District Council (TCDC) Facilities Manager Derek Thompson says council staff and contractors have been trained to identify myrtle rust and what steps to take.

"If it's detected, we notify the Ministry for Primary Industries and ask for instructions. There have been two sites identified in the Coromandel with myrtle rust, in Waitete Bay and outside our Council office in Whitianga.

"In the first case, MPI sent in people to remove the infected plants. In the second case, MPI gave instructions to remove the infected plant. This was done according to MPI's protocols for handling myrtle rust: the infected plant is pulled out and fully bagged for disposal and any tools that come into contact with the infected plant are sanitised."

Biosecurity New Zealand says myrtle rust spores are microscopic and can easily travel large distances by wind, or via insects, birds, people, or machinery. Once the spores reach a susceptible myrtle plant they attach and germinate on the leaves, stems or flowers and the myrtle rust fungus grows, stealing nutrients and energy from its host.

Mr Thompson says it can help if landowners know how to identify myrtle rust on their own properties and what steps they should take.

What is Myrtle Rust?
* Myrtle rust first appears in bright yellow, powdery eruptions on the underside of young leaves, appearing on both sides of leaves as it grows.
* The pustules darken with time, and the leaves may become twisted and die.
* Myrtle rust was first detected in Australia in 2010. Initially, the Australian Government tried to contain the disease, but it quickly spread and reached our shores in May last year.

If you find myrtle rust
* Don't touch it as you may spread it.
* Call the MPI Exotic Pest and Disease Hotline on 0800 80 99 66.
* If you have a camera or phone, take clear photos, including the whole plant, the whole affected leaf, and a close-up of the spores or affected area.
* Don't try to collect samples as this may spread the disease.

A link to help landowners can be found on the biosecurity website at www.biosecurity.govt.nz/protection-and-response/responding/alerts/myrtle-rust/managing-myrtle-rust-on-your-property/