Contractors wandered through Pukekura Park, New Plymouth fully dressed in hazard suits searching for myrtle rust.

Myrtle rust has been found in one of New Zealand's gardens of national significance.

Ministry for Primary Industries (MPI) confirmed that New Plymouth's Pukekura Park contains the fungus after contractors surveyed the park on Thursday.

Myrtle rust, thought to have blown in to New Zealand from Australia, attacks various species of plants in the myrtle family, such as pōhutukawa, mānuka, rātā, kānuka, swamp maire and ramarama.

Supplied Myrtle rust is a fungal disease that is found on plants such as pohutukawa and manuka.

So far, 210 sites across the country are confirmed to contain affected trees. Almost half - 101 cases - are in Taranaki, while four are in Northland, 32 in Auckland, 47 in Bay of Plenty, 22 in Waikato, and four in Wellington.

MPI myrtle rust response controller Catherine Duthie said in a statement that myrtle rust had infected an exotic Agonis flexuosa - commonly known as peppermint tree, peppermint myrtle or river myrtle - in Pukekura Park.

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SIMON O'CONNOR/STUFF Pukekura Park during the Festival of Lights.

It is one of the hundreds of trees of the myrtle species in the attraction.

Duthie said a field surveillance team will now check all myrtle species within a 500-metre radius of the infected tree in Pukekura Park.

She said if additional infections are found, the surveillance area may widen.

Supplied Pukekura Park is the 101st site in Taranaki found to have been affected.

MPI senior communications advisor Victoria Moss said the teams were assessing the situation and would then decide how to deal with the affected tree.

New Plymouth District Council chief operating officer Kelvin Wright said there were no plans to close any part of the park and the ongoing TSB Festival of Lights is unaffected.

The discovery comes after an investigation in December found that the cost of myrtle rust to New Zealand's economy could stretch into the thousands of millions and cause some regions' economic activity to fall by up to 10 per cent.

Supplied Myrtle rust was first discovered in Taranaki in May.

The appearance of the fungus has prompted the largest seed banking of the vulnerable native species ever conducted by the Department of Conservation (DOC), with nearly six million mānuka seeds collected alone.

The prediction, contained in a presentation delivered by Ministry for Primary Industries senior adviser for conservation Rebecca Martin in May, said the fungus could lead to a 0.10.5 per cent drop in GDP putting possible losses as high as $1390 million.

ASB rural economist Nathan Penny said the industry was monitoring myrtle rust closely, with the devastating effect of PSA on the kiwifruit industry still fresh in economists' memories.

The predicted impacts were at the smaller end of the scale in terms of the broader economy, Penny said, and most Kiwis would not be affected, but smaller communities and those that relied on horticulture may feel the sting.

MPI director of readiness and response Geoff Gwyn said the response was in an active operational phase and projected economic impacts had not yet been completed.

"We continue to be fully focussed on trying to contain and slow the disease spread. Early assessments were developed for a range of different outbreak scenarios, however it is still too early to accurately know which scenario New Zealand can expect and therefore, the level of economic, environmental and cultural impact."

In late November Stuff reported that the total number of infected sites in the region was 82 since the disease was first detected in Taranaki in May.

The fungus was first discovered in the region in a Waitara nursery.

By June there were restrictions on moving myrtle species plants in and out of North Taranaki after the disease infected more than 50 properties in the region.

The Manukorihi Golf Club was closed and eight pohutukawa trees were destroyed after myrtle rust spores were discovered there too.

By December biosecurity staff checking for myrtle rust outbreaks were been given full powers to go onto private property without prior warning to the owner.