The Native Guava (Rhodomyrtus psidioides) is a Critically Endangered species that was once reasonably common along the east coast of Australia from Hervey Bay to Sydney. It has been almost completely wiped out due to the introduced fungus, Myrtle Rust, which affects all parts of the plant and eventually kills the plant. Myrtle Rust was first detected in Australia in 2010 and has spread widely through native plants within the Mrytaceae family. It has particularly affected and caused major declines in species of Rhodamnia, Gossia and Rhodomyrtus.
Most Native Guava now found in the wild are suckers off the roots of trees that are long gone. These suckers reach about a foot high before they are killed by Myrtle Rust as new growth is highly susceptible to this fungal disease. This cycle of sprouting and being knocked back can continue over many years, until finally the plant stops sending out suckers and fully dies.
In October 2022, six Native Guava plants, ranging from 1-3 metres in height, were found on a Land for Wildlife property in Logan and appear to be resistant to Myrtle Rust as there were no signs of rust on the plants. What is even more exciting is that these plants put on a seriously impressive flowering display and then fruited profusely in the months following.
Logan Land for Wildlife Officers and the landholder worked with the Department of Agriculture and Fisheries to collect cuttings for testing and propagation. This will tell us more about the level of resistance these plants have to Myrtle Rust.
Fruit was also sent to Brush Turkey Enterprises Nursery on the Sunshine Coast for propagation. The fruit recently germinated and the seedlings are growing well. So far, no fungicides have been used on these propagated Native Guavas, which is a great sign that they are growing without signs of rust.
We are continuing to monitor these six plants in Logan and, more than a year on from their discovery, they are still growing well with no signs of Myrtle Rust. So, let’s hope that these plants do turn out to be Myrtle Rust resistant and can potentially help save Native Guava from extinction.
Article and photos by Nick Swanson
Land for Wildlife Officer