Biosecurity teams in Kerikeri have begun trying to contain just-detected fungal plant disease myrtle rust, which poses a serious threat to pohutukawa, rata and other iconic New Zealand species.
After the disease's discovery on Tuesday evening, a field headquarters has been set up in the Northland town as ground teams continue work at the plant nursery where plants were found with the distinctive yellow growths on their leaves.
The teams had already sprayed the affected property with a fungicide and were now working out from the nursery methodically, searching myrtle species trees in the wider area for signs of the disease, Ministry for Primary Industries (MPI) response director Geoff Gwyn said.
"The nursery itself is under biosecurity controls and restrictions are in place on the movement of plants and people on and off the property.
"We have also contacted all other nurseries in the area to prevent the movement of any infected plants out of the area."
MPI staff were checking for signs of myrtle rust at about 800 high-risk surveillance sites across the upper North Island, including 300 sites in Northland.
Department of Conservation officials have also started targeted searches of myrtle species across conservation land.
A large response team was driving activities from Wellington, and planning is under way for future effort.
Gwyn said diseases such as myrtle rust were notoriously difficult to control: internationally it had never been successfully eradicated.
"However, we have the best and earliest opportunity here to strike what appears to be a contained incursion. Only time will tell if this is the case."
MPI was working with partners, including the forestry, nursery and honey industries to ensure their members are aware of what they can do to help.
A public awareness campaign has also been launched.
People were encouraged to be alert for signs of myrtle rust, which appeared as bright yellow or orange powdery patches on leaves of myrtle plants. Affected leaves may buckle or die off.
It poses a serious threat to some of our most cherished plant species - including pohutukawa and rata - severe infections can kill plants.
Plants that are also important to our honey industry, such as manuka and kanuka, could also be affected, which could severely affect New Zealand's annual $300 million of honey exports.
Other at-risk species include feijoa, gum and bottlebrush.
In Australia, the fungus has had different some myrtle species more than others.
It had caused the extinction of several treasured plant species of significance to aboriginal Australians.
Anyone believing they have seen myrtle rust on plants in New Zealand were asked to call MPI on 0800 80 99 66.
It was important for people not to touch the plants or attempt to collect samples as this would spread the disease.