Some of New Zealand's most recognisable native trees could be at serious risk after the arrival of the myrtle rust disease.
The Ministry for Primary Industries has launched a full-scale biosecurity operation after the yellow fungus was found in Northland this week.
The air-borne disease has been killing myrtle species in Australia since 2010 and the Ministry has warned it could seriously affect natives such as pohutukawa, rata and manuka.
Biosecurity Institute president Darion Embling said he was gutted when he heard the disease had been found.
"Once this thing gets established, if it can attract what's happened in Australia, we're going to lose massive areas of kanuka, potentially pohutukawa. I'm just thinking of me going up to the Coromandel Peninsula, sitting under a beautiful pohutukawa tree on a summer's day. Is that going to be like that in a few years time?"
Mr Embling said people needed to know what the fungus looked like, and report it if they saw it.
The local honey industry is also watching with concern at the possibility of the plant disease devastating native manuka.
John Rawcliffe, a spokesperson for the Unique Manuka Factor Honey Association, said the industry had been advised about the disease.
"We don't know what could happen, so we need to keep a watching brief, we may need to look at breeding programmes and so forth to deal with it."