As with other positive finds, the trees are having their foliage sealed to prevent spore drift and are then being removed and deep buried.
"All efforts to date have been to contain infection where it is found. However, we have been planning for the possibility that it turns out to be widespread and are realistic that it won't be feasible to keep removing all infected trees found long term.
"This new find will see us review our tactics and could signal a move to a longer-term approach to managing it in partnership with others, including local authorities, iwi and hapū, plant production industry, and interested individuals and groups.
"We'll be keeping people informed about any decisions and will provide the most up-to-date information about best practice in fighting this disease," Dr Duthie said.
In the meantime, MPI encourages everyone to keep an eye out for the disease in myrtle species.
"So far ramarama and pōhutukawa are the species we're finding most affected and these are the ones to look at carefully.
"If you think you've seen the distinctive yellow fungus, don't touch the plant or the rust, as this may spread it. If possible, get a good photo of the plant and the yellow patches, and contact MPI on 0800 80 99 66."