Myrtle rust: Help needed

July 3, 2018

What do you know about the increasing myrtle rust problem? Find out more here or help with research…

Queensland Herbarium’s Dr Jarrah Wills and Queensland Department of Environment and Science’s Keith Smith have been researching the fungal disease’s impact on the Wet Tropics.

This region now has a huge range of badly-impacted myrtle groups and seems to have been hit the hardest by the current strain. Myrtle rust infects plants in the Myrtaceae family, such as lily pily, tea tree and bottle brush, and has spread from NSW all the way to Bamaga at the tip of Cape York since it was first detected in Australia in 2010.

The fungal disease is severely impacting range-restricted endemics such as Gossia lewisensis, keystone ecological species such as River Gum (Tristaniopsis exiliflora) and large emergent trees including the Johnstone River Yellowwood (Ristantia pachysperma). Some species are much more susceptible than others and there seem to be differences in resistance at different life stages and seasons.

Myrtle rust is so widespread now that it is unlikely nursery stock will further spread it. The live plant trade, people, water and particularly wind have made a big impact.

One concern is that seedlings may be carefully nurtured and leave the nursery free of myrtle rust only to rapidly pick up the rust when planted in the landscape - and then die as result. However, no systematic monitoring has occurred to determine the short and long-term effect of myrtle rust on vulnerable Myrtaceae in plantings.

The question is now being asked: Should nurseries avoid myrtle rust-vulnerable species all together, or should they persist and use surviving plants that show strong resistance? Should nurseries persist with myrtle rust control measures or stop? Do nurseries/restoration workers have the capacity to investigate survival of planted-out species and share knowledge of which species battle through and survive? Or are they better placed to avoid vulnerable species all together in search of maximum survival rates?

Actions urgently need to be investigated to prevent other strains of myrtle rust entering Australia, to selectively breed for resistance, to translocate outside myrtle rust range and to monitor ecological impacts as they unravel.

If you have feedback or you can help with myrtle rust studies, please contact Dr Jarrah Wills at Jarrah.Wills@des.qld.gov.au