Myrtle Rust – Being Aware of the Threat

This spring, every gardener must be cautious and on the lookout for myrtle rust, as it is spreading across the New Zealand mainland after its discovery in May this year. I am not wanting to put you off these beautiful gardening days. Therefore, I believe that it is important that all of you are aware and know what to do if you din myrtle rust in your garden. Please read on to find out how you can identify it and what you can do to stop it from spreading.

Chilean guava with myrtle rust on stem.

What is myrtle rust and how can I recognise it?

Myrtle rust is a fungal disease that has been detected on over 440 species, severely attacking plants in the myrtle family. These including some of our iconic natives such as pōhutukawa, kānuka, mānuka and rātā, as well as some commercially-grown species, for example, eucalyptus, guava and feijoa. The disease is also known as guava rust or eucalyptus rust. Luckily, myrtle rust rarely kills adult plants. However, it attacks young, soft, actively growing leaves, shoot tips and young stems with microscopic spores that develop into bright yellow or orange powdery patches on them. Other ways of recognition are the brown and/or grey pustules, which are older spores, and leaves that are buckled and twisted, thus dying off.

What are nurseries doing and how can I help?

Because the spores can spread easily and rapidly across large distances through wind, or via contaminated clothing, insects, rain splashed and equipment, a contamination is difficult. After the first findings on the Raoul Island in March 2017 the Ministry for Primary Industries (MPI) has developed some management protocols in conjunction with New Zealand Plant Producers Inc. These legal controls are advising nurseries of hygiene and containment measures. Further, cut flowers and foliage are prohibited to be imported from affected regions such as New South Wales, Queensland, Victoria and Tasmania.

The MPI and DOC have released a message to the public, that if you were to spot myrtle rust in your garden or the surrounding nature: please do not touch the fungal disease! If you can, take a picture and be sure to call the MPI’s exotic pest and disease hotline on 0800 80 99 66. Currently, affected areas are Northland, Taranaki, Waikato and the Bay of Plenty, but due to the spreading via wind, I advise to be aware of the threat everywhere in New Zealand.

More information

Hero image by Casliber – Own work, CC BY-SA 3.0

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