Myrtle rust (eucalyptus/guava rust) caused by the fungus Puccinia psidii affects plants in the Myrtaceae family, which includes many Australian natives such as eucalypts, paperbark, bottlebrush, tea tree and lilly pilly. The disease is native to South America and was first described in 1884 in Brazil affecting guava, and more recently affecting eucalypt plantations (hence the common names guava and eucalyptus rust). P. psidii was identified as a ‘high to extreme risk’ biosecurity threat to Australia prior to its introduction here, due to the potential impacts on plant industries that rely on myrtaceous plants, and the significance of Myrtaceae in the Australian environment. A strain of Puccinia psidii (referred to as myrtle rust) was first detected on the central coast of New South Wales (NSW) in April 2010 and then quickly spread to Queensland (in December 2010) and Victoria (in December 2011), affecting more than 200 host species.

Research outcomes

This research into the epidemiology and host specificity of myrtle rust will:

• Help inform the development of disease forecasting systems to assist in fungicide management systems for plant industries reliant on species of Myrtaceae.
• Provide important baseline information to help gain an understanding of environments most threatened by myrtle rust allowing for development of strategic disease management programs.
• Provide information on the strain of P. psidii present in Australia, thus improving our capabilities to detect new strains of the rust.
• Provide information on host resistance mechanisms for the development of rapid resistance screening methods.
• Provide crucial data for more accurate predictive modelling systems for future monitoring and impact studies for states and territories where the disease has yet to spread, and other countries where myrtle rust has not yet been detected.
• Provide data for predicting impact levels in relation to future climate patterns within states of Australia already impacted by the disease.

Research implications 

The information and knowledge generated within this project provides the basis for other areas of research and development on this disease e.g. surveillance, population genetics, resistance breeding and monitoring impacts.

Acknowledgements

• Dr Gordon Guymer, Department of Science, Information Technology, Innovation and the Arts, Queensland
• CRCNPB
• New South Wales Government
• Queensland Government