Myrtle rust – MPI reports two more cases confirmed in Taranaki

Two further properties in Taranaki have been confirmed positive with myrtle rust infection today. Both are plant businesses, one a further nursery in Waitara and the other a garden centre in New Plymouth.

This brings the total number of known affected properties to five – a nursery and adjoining property in Kerikeri, two plant nurseries in Waitara and a garden centre in New Plymouth.

The ministry says the new finds are disappointing but not unexpected. It expects to continue to find new locations of infection given the most likely scenario is that the fungal spores entered New Zealand from Australia during a major wind event.

All infected properties are “restricted places”, meaning there are restrictions on the movement of plants or other risk materials off the sites. Locations are being treated with fungicide, risk plants are being safely destroyed, and surveillance is underway in the areas surrounding the properties for signs of the disease.

The ministry says there are two main reasons why the rust is being found in plant nurseries.

* First, growing conditions there are ideal for the fungus with many vulnerable young plants in sheltered, warm and damp environments.

* Second,there has been a large amount of communication with the nursery industry and growers have been particularly vigilant in checking their plants.

Myrtle rust (Austropuccinia psidii) is also known as guava rust and eucalyptus rust.

It is a serious fungal disease that affects plants in the myrtle family, which includes pōhutukawa and mānuka. The first detection of the disease in mainland New Zealand was at a Northland nursery early this month.

The fungus attacks various species of plants in the Myrtaceae family, also known as the myrtle family. It is found in many parts of the world including New Caledonia and all along Australia’s eastern seaboard.

It is widespread on Raoul Island in the Kermadec group, about 1,100km to the north-east of New Zealand.

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

The spores are thought to be capable of crossing the Tasman Sea from Australia to New Zealand on wind currents.

Myrtle rust could affect iconic New Zealand plants including pōhutukawa, mānuka, rātā, kānuka, swamp maire and ramarama, as well as commercially-grown species such as eucalyptus, feijoa and guava.

Severe infestations can kill affected plants and have long-term impacts on the regeneration of young plants and seedlings.

Its impacts overseas have varied widely from country to country and plant species to species.

Myrtle rust shows up as yellow bumps and brown patches on leaves.

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

Symptoms to look out for on myrtle plants are:

* 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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