The garden is home to about 600 rare plant species from throughout the world, including one of New Zealand's rarest trees, Bartlett's rata. Garden team leader-curator Alan Matchett said myrtle rust was a ''major threat'' to plant species in the Myrtaceae, the myrtle family, which included the pohutakawa, rata, manuka and kanuka.
The heavy rust damage to pohutakawa trees on Raoul Island-in the New Zealand-administered Kermadec Islands 1100km north of Cape Reinga-showed the disease ''can develop very quickly'', Mr Matchett said.
North Island media have earlier reported hundreds of officials across the country have been scrambling to gather seeds of more than 30 native plant species now threatened by deadly fungal disease myrtle rust.
The Auckland Council and other regional authorities have been directed to collect seed of important native myrtle trees, in a nationwide emergency seed-banking effort being led by the Department of Conservation (Doc).
The rust has spread from the Kerikeri nursery where it was recently first found and officials say it may be impossible to contain the wind-blown scourge.
Ministry for Primary Industries director-general Martyn Dunne said if myrtle rust became established in New Zealand, current trees might not survive, but the next generation could be safeguarded by trying to breed disease-resistant strains.
Cultivars of New Zealand's rarest tree, Bartlett's rata - only 14 of which are known, all in a small area near North Cape - were kept at Dunedin's Botanic Garden and seeds of endangered species were being sent to a seed bank in Palmerston North for safe keeping, Doc officials said recently.
Mr Matchett confirmed the Dunedin garden was involved in collaborative efforts to protect endemic New Zealand plants, and was ''working in partnership'' with Doc.
Staff at the garden felt a ''buzz'' to realise the Dunedin facility could play an important role in helping to safeguard rare plants, such as Bartlett's rata, and to help provide cultivars to ensure the rare plant survived.
The garden was a place for recreation and enjoyment of nature, but also had a ''hugely valuable'' role in protecting rare and threatened plants, he said.
Horticultural apprentice Toni Robertshaw said the Botanic Garden was an ''amazing'' place to work and learn and the presence of rare trees like Bartlett's rata added to the experience.
