The Department of Conservation (DOC) has warned that the fungal disease myrtle rust poses a threat to New Zealand's iconic Christmas tree, the pōhutukawa.
Bay of Plenty, Taranaki and Auckland are the areas most seriously affected by myrtle rust.
Both DOC and Biosecurity New Zealand (part of the Ministry for Primary Industries), are encouraging the public to check their local myrtle plants this summer to help track the spread of the fungal disease myrtle rust.
Myrtle rust is likely to be more active during warmer weather and is likely to spread to new areas where it hasn't been seen before.
New Zealand's precious native myrtle plants including pōhutukawa, rātā, mānuka, kānuka and ramarama are vulnerable to the disease.
The fungus, which is mainly spread by wind, generally infects shoots, buds, and young leaves of myrtle plants. Infected plants show typical symptoms including bright yellow powdery spots on the underside of leaves.
If symptoms of myrtle rust are present the public is reminded not to touch the plant or collect samples, but take pictures and report it to Biosecurity New Zealand's Exotic Pest and Disease Hotline on 0800 80 99 66.
As of this month, the disease has been confirmed on 811 properties across most of the North Island and upper areas of the South Island.
Biosecurity New Zealand and DOC are currently working in partnership to identify ways to best manage the disease and support the health of myrtles in the future.
Biosecurity New Zealand's manager for recovery and pest management, John Sanson, says a cross-sector working group has developed a national long-term management plan for myrtle rust.
"This working group includes members from Biosecurity New Zealand, the Department of Conservation, Māori organisations with an interest in biosecurity, the Ministry for Culture and Heritage, regional councils, and the Project Crimson Trust. The group has provided recommendations on agreed goals that will underpin our collective approach to managing myrtle rust.
"We are also investing significantly in scientific research to develop new tools, build understanding of myrtle rust and explore possible long-term management options with a $3.7 million programme of research. An additional $5 million funding increase from the Strategic Science Investment Fund will build on work already being done by Government agencies, Māori, councils, and research providers over the next 3 years," Sanson said.
In the meantime, it is important to understand where the rust has spread to, what plants it is affecting (especially new ones) and where it is active.
DOC's project manager for myrtle rust, Fiona Thomson, says that a large programme of seed collection is underway to safeguard native myrtle species from extinction.
"We have 37 different myrtle species in New Zealand and so far we've made great progress – 57 per cent of the seed collections needed have been banked in the New Zealand Indigenous Flora Seed Bank (NZIFSB)", Dr Thomson said.
DOC also wants to understand the spread of the disease so is asking staff and the public to keep an eye out for myrtle rust over the summer.
"Everyone has an important role to play in biosecurity. The more eyes looking out for myrtle rust means the better we can monitor this disease and protect our precious myrtles, including our iconic Christmas tree, pōhutukawa."
A map of areas where myrtle rust has been found in New Zealand and resources on what to look for, what to do if you find myrtle rust and how to manage it are available here.