The majority of the detections were on the plant Ramarama, but also native pohutukawa and the exotic myrtles Lilly Pilly/monkey apple, bottle brush and willow myrtle.
"Myrtle rust is likely to be more active during warmer weather with late summer and autumn likely to be the worst time for infection and spore risk, " the spokesperson said.
Myrtle rust has spread to 895 identified properties nationwide since 2017.
Biosecurity New Zealand has commissioned a $3.7m comprehensive research programme made up of more than 20 specific projects to better understand myrtle rust.
The Government is set to pump another $13.75 million into research to combat the spread of myrtle rust and kauri dieback in the next three years.
This is on top of previous research funding of $6.9m for myrtle rush.
Tauranga Moana Biosecurity Capital collective co-chairperson Graeme Marshall said the latest detection cases in the Bay was "very disappointing".
Marshall said a considerable amount of work was already going on to try and manage the risks, particularly in relation to pohutukawa on Mauao.
But continuing surveillance is the key to helping to manage the threat, he said,
"This is why were want 4.7 million New Zealanders to be part of the country's biosecurity team by reporting cases and helping to reduce the spread of this nasty fungal disease."
Marshall said whether it was myrtle rust, kauri dieback or some other invasive pest it needed everyone to play a role in combating any biosecurity threats.
Shane Grayline, the Bay of Plenty Regional Council's biosecurity team leader, said it was hard to imagine the region without our beautiful pohutukawa trees lining our coasts.
"Or rata vines cloaking trees in the bush or being able to enjoy feijoas or even worse, and what would happen to our beekeeping industry if we lose our mānuka.
"However these are the species that myrtle rust threatens and why we are working hard with MPI and landowners to stop the spread of the disease," he said.
If a plant is showing symptoms people should not touch the plant or collect samples.
Anyone who accidentally come in contact with an affected plant or the rust, should bag their clothing and wash their clothes, bags, shoes and boots.
If you can, take a photo of the rust and the plant it's on and phone the MPI's exotic pest and disease hotline 0800 80 99 66.