Myrtle rust is a plant fungal disease that poses a threat to public parks, native forests and private gardens, as well as the nursery, forestry and beekeeping industries. It was first detected in Victoria in 2011, and earlier this year an infection was confirmed at Maranoa Gardens in Balwyn.
Myrtle rust affects plants in the Myrtaceae family, which are common across Boroondara, and include plants like bottlebrush, eucalyptus and brush box. Popular garden plants like Lophomyrtus ‘Black Stallion’ and lemon myrtle are also susceptible.
It is therefore critical that if found, the disease is reported so it can be contained. Nurseries and plant sellers should be aware of the disease and note that selling a diseased plant can carry a fine.
What myrtle rust looks like
The first signs of myrtle rust infection are tiny raised spots that are brown to grey, often with red-purple haloes. Up to 14 days after infection, the spots produce masses of distinctive yellow/orange spores. You can see what myrtle rust looks like on Agriculture Victoria's website.
Myrtle rust attacks young, soft, actively growing leaves, shoot tips and young stems, as well as fruits and flower parts of susceptible plants. The disease can kill young shoot tips, compromising the appearance of the plant and in severe cases, killing the plant.
Fortunately, Melbourne’s conditions are mostly not conducive to the disease; however, certain domestic and botanical gardens have conditions that are ideal for the disease to thrive. The following conditions need to be met for an infection to occur; low lighting (such as at night), water on the leaf of the plant (such as dew, rain, or very high humidity) and when the temperature is between 15 and 23°C. The risk of infection is highest during autumn and spring.
Experience with the disease elsewhere in Australia indicates that eradication is unlikely, so governments, affected industries and agencies are focusing on minimising the disease’s spread and impact.
Reporting myrtle rust
If you think you have found myrtle rust in your home or in a public setting, please telephone the Exotic Plant Pest helpline on 1800 084 881.
Alternatively, you can take photos of the plant material and email them to [email protected] together with your contact phone number.
Avoid spreading the disease
You can help stop the spread by:
- not touching, moving or collecting samples of the suspect plant material
- not going to another site with any host materials after handling suspect material.
For more information on the disease, including how to reduce its spread on your property, see Agriculture Victoria’s website.