Myrtle rust infected sites in Taranaki grows as summer approaches

Friday, 24 November 2017

Myrtle rust control zone remained in place in Taranaki during summer.

Myrtle rust disease is on the march as summer approaches with nine new infestations found in Taranaki during the past fortnight.

This brought the total number of infected sites in the region to 82 since the disease was first detected in the region in May.

MPI incident controller Catherine Duthie said there had not been a significant spike in new detections in the region so far this spring.

'We've had nine new detections in the past few weeks with six of these were sites already under controlled restrictions where we'd found it before and treated it, but reinfection had occurred,' she said.

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Three of the infestations were found on properties within 50 metres of the original restricted properties, she said.

MPI biosecurity staff had visited all restricted areas, as well as placed 50 metre restricted zones around each site over the past few months, she said.

'We plan to revisit them all again, as well as the 50 metre surrounding areas, in December.

'As the situation unfolds we will be updating our activities in the upcoming months, and will re-evaluate our plan for the rest of the summer.'

Consistently warmer temperatures are what the rust needs to develop and release spores, she said.

'We don't know what we will see in Taranaki this summer.

'The best information from overseas is that we could expect to find more as the weather warms up.'

Duthie said the public should continue to look out for the distinctive yellow myrtle rust spores on plants and trees, such as pohutukawa, ramarama and manuka, in gardens and in the wild.

If there is an infestation the public should call MPI on 0800 80 99 66.

'In terms of what people can do to control myrtle rust, our advice at this time is for people to seek advice from their local garden centre,'she said.

It was possible to use some fungicides to prevent infection but there are significant factors to consider and once prevention was started it would require continuous treatment, she said.

Chemicals designed to prevent infestation have some drawbacks and cannot be used around fruit or vegetable crops.

'Garden centres are best placed to work with gardeners on the appropriate course of action for their individual property.'

Duthie said it was unknown how myrtle rust would behave in New Zealand and what the impacts will be on our plants and trees.

The latest outbreak was detected this week on ramarama plants at a commercial nursery near Waimauku, West Auckland.

'To date, the most significant impacts have been on ramarama and pohutukawa and many locations and plants may not be seriously affected.'

Duthie said the latest outbreak was 'expected' after a dormant growing period during winter.

MPI anticipated new infections to be identified as summer approached and the fungus released spores again, she said.

New Plymouth nurseryman Vince Naus said garden centres were still prevented from selling any plants from the myrtaceae family, except feijoa which the rust disease was not known to affect.

To help identify myrtle rust go to MPI website – www.mpi.govt.nz/myrtlerust