Myrtle rust arrives in Nelson

Myrtle rust has been found on ramarama and po¯ hutukawa trees in and around Nelson city.

A Ministry of Primary Industries (MPI) surveillance team found the new infections on four sites in the area recently. The airborne disease has spread from the North Island, and was found in Collingwood earlier this year.

An MPI spokesperson said property owners and the Nelson City Council had been informed of the infections in Nelson. ‘‘A decision on the appropriate management approach will be made very soon.’’

Biosecurity teams were seen looking at properties in the Founders Heritage Park area at the end of July.

Myrtle rust affects plants in the myrtle family, which includes iconic native species like po¯hutukawa, ma¯nuka, ra¯ta¯, ka¯nuka, swamp maire and ramarama, as well as commercially grown species such as eucalyptus, feijoa and New Zealand cranberry.

The spores are thought to have crossed the Tasman Sea from Australia to New Zealand on wind currents. Severe infections can kill affected susceptible plants and have long-term impacts on the regeneration of young plants and seedlings.

‘‘It is not yet known how this disease will affect New Zealand species or ecosystems, as impacts may take years to identify,’’ MPI said. ‘‘Overseas, its impacts have varied widely from country to country and plant species to species.’’

The spokesperson said a paper published this year predicting the climatic risk of myrtle rust during its first year in New Zealand showed Nelson had a ‘‘moderate to high’’ risk of developing infections.

The infection risk and impact depended on a combination of suitable climatic conditions, host availability and host susceptibility, and could vary over time depending on those factors.

Nelson City Council group manager environmental management Clare Barton said the council could confirm that myrtle rust had been found on a pohutukawa tree in Tahunanui Reserve, but could not confirm the other finds.

‘‘We are awaiting guidance from MPI, which is the lead agency on this issue, as to how best to respond. Council encourages anyone discovering or suspecting myrtle rust on plants to contact the biosecurity freephone number, 0800 80 99 66.’’

The latest number of infected sites across New Zealand is 766.

‘‘We are awaiting guidance from MPI ...asto how best to respond.’’ Clare Barton, Nelson City Council

Myrtle rust, which affects native plant species like pohutukawa, manuka, rata and kanuka, was found to have spread from the North Island to Golden Bay earlier this year, and has now been found in Nelson city.