On guard for myrtle rust

Myrtle Rust. Department of Agriculture and Food, Western Australia, picture.

GISBORNE District Council is warning that a fungus that could wreak havoc with the district’s pohutukawa, eucalyptus and manuka trees may already be here but may have gone unnoticed.

Myrtle rust has been found all over the North Island since being it was first discovered in New Zealand in early May at a nursery in Northland.

The spores are thought to be capable of crossing the Tasman Sea from Australia to New Zealand on wind currents, and the experts say that is probably how it arrived on our shores.

“While it has not been officially found in Gisborne it is possible it is already here andhas just gone unnoticed,” the council’s environmental and science manager Lois Easton said.

The rust is a serious fungal disease that affects plants in the myrtle family, which includes pohutukawa, eucalyptus and manuka.

It has devastated ecosystems in Hawaii and the east coast of Australia and been identified in the top three biosecurity threats to New Zealand by the Ministry for Primary Industries.

The whole Gisborne district falls into the high-risk category, and particularly up the East Coast where rainfall can be high and temperatures hot.

“It is a tremendous threat to pohutukawa particularly,” Ms Easton said.

“Any chance we have of controlling its spread lies in early detection and we need our community out there being our eyes on the ground, looking out for it.”

If it is spotted the community is warned not to touch it, as this can help it spread.

“Just take a photo and call us,” Ms Easton said.

In March myrtle rust was found to be widespread on pohutukawa on Raoul Island, and in early May was found in plants at a nursery in Northland.

In the following two months it was found in Taranaki, Waikato and in July, in the Bay of Plenty.

It has now been found in Auckland and Wellington.

Myrtle rust generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers, and fruit.

The spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

The disease thrives in moist conditions with temperatures of 15-25 degrees Celsius, when it is easily able to be identified on infected plants.

Severe infestations can kill affected 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.

MPI is working to identify approaches to managing this disease, but it says rust diseases are difficult to control.

A Myrtle Rust Reporter app has been designed to help people take part in a nationwide move to monitor myrtle rust. It allows users to record a dozen potential host plants and easily report anything they find suspicious.

The app is freely available in the iPhone and Android app stores.


GISBORNE District Council is warning that a fungus that could wreak havoc with the district’s pohutukawa, eucalyptus and manuka trees may already be here but may have gone unnoticed.

Myrtle rust has been found all over the North Island since being it was first discovered in New Zealand in early May at a nursery in Northland.

The spores are thought to be capable of crossing the Tasman Sea from Australia to New Zealand on wind currents, and the experts say that is probably how it arrived on our shores.

“While it has not been officially found in Gisborne it is possible it is already here andhas just gone unnoticed,” the council’s environmental and science manager Lois Easton said.

The rust is a serious fungal disease that affects plants in the myrtle family, which includes pohutukawa, eucalyptus and manuka.

It has devastated ecosystems in Hawaii and the east coast of Australia and been identified in the top three biosecurity threats to New Zealand by the Ministry for Primary Industries.

The whole Gisborne district falls into the high-risk category, and particularly up the East Coast where rainfall can be high and temperatures hot.

“It is a tremendous threat to pohutukawa particularly,” Ms Easton said.

“Any chance we have of controlling its spread lies in early detection and we need our community out there being our eyes on the ground, looking out for it.”

If it is spotted the community is warned not to touch it, as this can help it spread.

“Just take a photo and call us,” Ms Easton said.

In March myrtle rust was found to be widespread on pohutukawa on Raoul Island, and in early May was found in plants at a nursery in Northland.

In the following two months it was found in Taranaki, Waikato and in July, in the Bay of Plenty.

It has now been found in Auckland and Wellington.

Myrtle rust generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers, and fruit.

The spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

The disease thrives in moist conditions with temperatures of 15-25 degrees Celsius, when it is easily able to be identified on infected plants.

Severe infestations can kill affected 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.

MPI is working to identify approaches to managing this disease, but it says rust diseases are difficult to control.

A Myrtle Rust Reporter app has been designed to help people take part in a nationwide move to monitor myrtle rust. It allows users to record a dozen potential host plants and easily report anything they find suspicious.

The app is freely available in the iPhone and Android app stores.


Symptoms on myrtle plants

  • The first signs of myrtle rust infection are tiny raised spots that are brown to grey, often with red-purple halos. Up to 14 days after infection, the spots produce masses of distinctive yellow spores.
  • Bright yellow powdery eruptions appearing on the underside of the leaf (young infection)
  • Bright yellow powdery eruptions on both sides of the leaf (mature infection)
  • Brown/grey rust pustules (older spores) on older lesions
  • Some leaves may become buckled or twisted and die off

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