Myrtle rust

Myrtle rust has been detected in the ACT. It was most recently detected near the National Museum of Australia in February 2025.

About the disease

Myrtle rust (Austropuccinia psidii) is a fungal disease which infects over 380 plant species in the Myrtaceae family. Common Australian Myrtaceae species include eucalyptus, willow myrtle, turpentine, bottlebrush, paperbark, tea tree and lilly pilly.

Why it is a problem

Myrtle rust spreads aggressively through wind-borne spores, stunts plant growth, reduces fertility and causes canopy collapse, pushing vulnerable native species toward extinction.

It also affects commercial industries including nurseries, timber plantations, tea tree oil and lemon myrtle producers.

What to look for

• Generally, myrtle rust starts as small purple spots on leaves. Bright yellow spores form in pustules within these purple spots. Pustules fade to dull yellow and then grey as the infection ages.
• In severe infections, spots enlarge and merge, often causing leaf distortion. Heavy infection can result in the death of soft plant material. Whole plant death may occur in highly susceptible hosts.
• Plants with dark purple leaves such as willow myrtle 'Afterdark' do not display obvious symptoms of early infection. Disease becomes apparent once the bright yellow pustules form on both surfaces of the infected leaf.

How it spreads

Myrtle rust is highly transportable through the spread of powdery, bright-yellow spores that are easily transported by wind and water (through run-off).

It is also spread through animals, insects or people picking up spores on themselves or their clothing or equipment, transferring them to new plants.

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