Assessing the impacts of myrtle rust on forest dynamics and function

The Queensland University of Technology (QUT)-led research stream is investigating how myrtle rust affects forest dynamics, particularly in forest ecosystems associated with the Gondwana Rainforests in south-east Queensland and northern New South Wales.

This work focuses on understanding which forest characteristics increase vulnerability to myrtle rust. These may include disturbance history, fire, climate, soil conditions, land clearing, agriculture, proximity to roads and land-management practices.

Researchers are surveying forest patches to assess Myrtaceae species presence, myrtle rust infection levels, mortality, and the recruitment of other plant species after myrtle rust impacts. This will help identify which functional groups are being lost or gained as forest communities change.

Early findings suggest historical land clearing may influence the density and exposure of some highly susceptible tree species. This work will help land managers identify forest patches that contain surviving individuals, areas heavily impacted by myrtle rust, and places where targeted management or restoration may be needed.

Key research areas

This research is:

• identifying forest characteristics linked to higher myrtle rust impacts
• assessing how disturbance history influences susceptible species and disease severity
• investigating how myrtle rust changes forest structure, recruitment and ecological function
• identifying landscape-scale indicators to prioritise areas for monitoring, protection or restoration
• developing recommendations to support forest management and long-term monitoring.

Pathway to impact

This research will support forest management by:

• improving understanding of which forest ecosystems are most vulnerable to myrtle rust
• helping identify priority areas for monitoring, protection and restoration
• informing ecological community management and threat-abatement planning
• guiding long-term monitoring of forest condition and host–pathogen dynamics.

The James Cook University (JCU)-led research stream is investigating the ecological and genetic consequences of myrtle rust on priority Myrtaceae species, including kanuka box in the Wet Tropics and other highly susceptible species in decline.

Kanuka box grows along fast-flowing rocky watercourses in Queensland’s Wet Tropics and helps stabilise banks and prevent erosion in catchments connected to the Great Barrier Reef. Myrtle rust impacts on kanuka box therefore represent a serious ecosystem-level threat.

Researchers are using field surveys, herbarium records and genetic analysis to understand patterns of resilience and vulnerability in kanuka box populations. This work will help assess disease impacts, genetic diversity, dieback, regeneration and the potential for longer-term monitoring.

The JCU-led extension activity will also investigate population genetics in 6–8 restricted and susceptible Myrtaceae species undergoing rapid decline. This will help inform resistance screening, disease-resistance breeding strategies, ex-situ germplasm collection and monitoring of genetic bottlenecks.

Key research areas

This research is:

• assessing myrtle rust impacts on kanuka box in Wet Tropics stream systems
• investigating genetic diversity and patterns of resilience in affected species
• identifying disease impacts across life stages, populations and sites
• improving understanding of species vulnerability, resistance and recovery potential
• supporting conservation actions such as germplasm collection, resistance screening and long-term monitoring.

Pathway to impact

This research will support threatened species conservation by:

• improving understanding of species-level vulnerability and resilience to myrtle rust
• informing germplasm collection, resistance screening and future breeding strategies
• supporting conservation planning for highly susceptible Myrtaceae species
• providing ecological and genetic evidence to guide monitoring and biosecurity management.

A recent publication linked to this project investigated how historical land use can influence the severity of myrtle rust impacts in wet sclerophyll forests in eastern Australia.

Access paper: Land-use history and myrtle rust impacts

The study found that forest patches with higher levels of historical land clearing had greater densities of susceptible rainforest Myrtaceae species in the subcanopy, particularly Archirhodomyrtus beckleri. These sites also showed more severe myrtle rust impacts. The findings suggest that forests regrowing after disturbance may be more vulnerable to myrtle rust because of the composition of their subcanopy layer.

This research highlights the importance of considering land-use history when identifying forest patches that may need targeted monitoring, weed control, restoration or protection of healthier individuals of species threatened by myrtle rust.