The fungus Uredo rangelii (myrtle rust) has been detected on two commercial properties on the New South Wales central coast.  Myrtle rust is considered to be part of a group of rust fungi collectively known as eucalyptus/guava rust.  The Department of Primary Industries and Department of Sustainability and Environment have circulated Emergency Plant Pest Alerts. Severe rust disease in young trees may kill shoot tips, causing loss of leaders and a bushy habit.  Rusts are highly transportable and are most often dispersed by wind but they may also attract bees who work the spores on leave.  The spores can also be spread via contaminated clothing, infected plant material and insect movement.  Early identification of this rust is vital for effective management. Any rust noticed on Myrtaceae species should be reported by calling the Exotic Plant Pest Hotline on 1800 084 881.

Myrtle Rust (Uredo rangelii) on Agonis flexuosa, cv. Afterdark (willow myrtle) Photo: Dr Angus Carnegie

Host species

In Australia, myrtle rust has recently been detected on Agonis (willow myrtle), Syncarpia (turpentine) and Callistemon(bottlebrush) species.

Internationally, there are unconfirmed reports of infection on some Eucalyptus species. It has also been confirmed on Myrtus, Syzygium and Heteropyxis species overseas.
To date, it has not been confirmed on Australian eucalypts.

Spread

Rusts are highly transportable. The most common dispersal mechanism is via wind, but they may also be dispersed by bees who work the spores on leaves.
The spores can also be spread via contaminated clothing, infected plant material and insect movement.

Identification

Myrtle rust produces lesions on young, actively growing leaves and shoots, as well as on fruits and sepals. Leaves may become buckled or twisted as a result of infection.
On turpentine and bottlebrush, rust lesions are purple in colour, with masses of bright yellow or orange-yellow spores. Occasionally, they may have dark brown spores.
Severe rust disease in young trees may kill shoot tips, causing loss of leaders and a bushy habit.

Reporting

Any rust noticed on Myrtaceae species should be reported. Please call the Exotic Plant Pest Hotline on
Freecall 1800 084 881.
Do not collect samples of suspected myrtle rust, as this could spread the disease.

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