What is myrtle rust?
Myrtle rust (Puccinia psidii
) is a fungus that can have a serious effect on a large number of plant species.
Myrtle rust is a single rust fungus species within the guava/eucalyptus rust family. There are some significant gaps in the scientific knowledge about myrtle rust. It appears to behave in a similar, but not identical, way to other guava/eucalyptus rusts.
There is ongoing research to gain a better understanding of myrtle rust.
The bright yellow pustules indicate the presence of myrtle rust. Photo: NRE Tas - Biosecurity Tasmania
What does myrtle rust look like?
Please refer to the myrtle rust fact sheet:
Myrtle Rust Biosecurity Fact Sheet
What do we know about myrtle rust?
Research being carried out as part of the response to the outbreak in NSW shows that:
- Spores transfer easily from an infected plant to susceptible host species (ie myrtaceae plants).
- Spores can be carried by non-myrtaceae species and these spores can then transfer to nearby susceptible species. In practice, this means nurseries and other people who move plants about could inadvertently spread myrtle rust by this means.
- A large number of plant species in the myrtaceae family are susceptible to myrtle rust.
The readily-visible signs of myrtle rust - the distinctive mass of spores - mostly disappear during winter months and the disease will be relatively dormant and signs of the disease will not be as distinguishable; and are likely to present as follows:
- Withered darkened growing tips, may have fine sandy appearance (grey spores) on darkened stem;
- Purple/brown discolouration on both sides of leaves (lesions), particularly on young leaves near tips of branchlets. May include leaf curling and crisped patches on leaves i.e. dried and brown.
What are the major gaps in our knowledge about myrtle rust?
The complete list of susceptible species is unknown. There may well be more names added to the list of known susceptible plant species as the situation on the mainland develops and more is learned about this disease.
What should Tasmanians be doing to minimise the risk of myrtle rust?
Tasmanian nurseries and other retailers selling plants have a key role to play in minimising the myrtle rust risk. Their most important task is to ensure that their staff all have some idea what myrtle rust looks like and to keep an eye out for it when handling stock.
Nurseries should also ensure that on-site hygiene standards are applied.
If you go bushwalking in Tasmania, please:
- keep an eye out for the distinctive yellow or orange spores on any myrtaceae plants.
If you see any such signs, contact NRE Tas on 1800 084 881.
If you are out of mobile phone range don't take a sample of the plant that appears infected. Instead, take a note of your location (GPS is ideal, but simple directions as to how to find the plant will be good) and, if possible, tie a ribbon or otherwise mark the affected plant. Then contact
1800 084 881 as soon as you can.