Myrtle rust spreads to Kerikeri and Mangawhai

Members of a multi-agency biosecurity response team checking for signs of myrtle rust soon after its discovery in Kerikeri last year.

Confirmation of new myrtle rust discoveries in the Kerikeri and Mangawhai areas prompted a plea from biosecurity officials last week for Northlanders to continue reporting any suspected cases of the fungal disease.

The latest Northland discoveries came a month after the Ministry for Primary Industries and Department of Conservation (DOC) announced that, given the prevalence of the rust across susceptible parts of the country, the fight against it was 'changing gear,' Dr Catherine Duthie (MPI) saying the windborne nature of the disease meant that despite an enormous national operational effort over the past year, which had seen more than 95,000 plants inspected and several thousand destroyed, containing it had not proved possible.

"We (MPI) have signalled for a while the likely need to change gear from intensive surveillance and the removal and destruction of host plants to one where we look to manage the disease over the long term," she said.

The Northland Regional Council said recent tests had confirmed the presence of myrtle rust at several new sites in Kerikeri — one of the first mainland areas in New Zealand affected by the disease last year — and at Mangawhai.

Biosecurity manager — partnerships and strategy Kane McElrea said the rust affected plants in the myrtle family, which included iconic species like pohutukawa, manuka and rata. It was also commonly found on ramarama, also known as bubble leaf.

With more than 50 infected trees over 20 sites covering six square kilometres in Kerikeri alone, news that the rust had now reached other parts of Northland was disappointing, but not unexpected, given the ease with which it could spread.

Mr McElrea added that although the primary responsibility for managing myrtle rust remained with the MPI, the regional council was still keen to work with the ministry and the wider community wherever practically possible.

Even with the recent change of approach from central government, Northlanders were still being encouraged to report any possible myrtle rust cases to the MPI's Exotic Pest and Disease Hotline — (0800) 809-966.

Mr McElrea encouraged Northlanders to check their properties for rust, but stressed the importance of not touching plants that might be displaying symptoms.

"Myrtle rust spores are microscopic and can easily be spread across large distances by wind, or via insects, birds, people or machinery, so instead of touching a suspicious plant, call the MPI hotline immediately," he said. "If you have a camera or phone camera, take clear photos, including the whole plant, the whole affected leaf, and a close-up of the spores or affected area of the plant."

Dr Duthie said in future the national focus would have to be on a science programme designed to lift understanding about the disease, such as ways to treat it, resistance and susceptibility, and improving seed banking collection.

A second key focus would be working with communities to support regional efforts to combat myrtle rust, which could include regional surveillance programmes, identification and protection strategies for taonga plants and special locations, advice to land owners, seed-banking and broad community engagement.

MPI and DOC would be engaging with iwi and hapu, territorial authorities, plant and nursery industries and communities to support the development of regional programmes.

As part of involving and informing communities, the ministry and DOC would call hui with iwi and councils in affected regions, including Northland, over the coming months.

DOC would also focus on seed collection to secure the long-term future of native myrtle plants, monitoring biodiversity impacts to inform science and management actions, and working to protect sites of high ecological and cultural significance.

Information about myrtle rust is at www.mpi.govt.nz