Features: A fungal infection that causes brown to grey lesions often
surrounded by yellow spores Where it's from: Central America and Caribbean, United States,
South America, Asia, South Africa, Oceania How it spreads: Importation of infected plant material; local spread
by spores on wind, and vehicles, clothing and machinery At risk: Over 100 known host plant species, mainly from the
Myrtaceae family; eucalypt plantations, native forests and
urban plantings
Guava rust symptoms on leaves. D.T. Junghans Embrapa, PaDIL.
Guava rust (also known as eucalyptus rust) is a fungal disease that causes deformed leaves, heavy defoliation of branches, dieback, stunted growth and often plant death.
Guava rust is closely related to myrtle rust (both part of the Puccinia psidii species complex), which was introduced to Australia in 2010 and has since spread across the eastern states, Tasmania and the Tiwi Islands in the Northern Territory, slowly altering ecosystems as susceptible species die.
Guava rust infects plants belonging to the Myrtaceae family, a large plant family that includes eucalypts, paper barks, bottle brushes and lilly pillies as well as other important Australian species.
Guava rust is one of the most serious exotic threats to Australia’s natural environment. It also threatens commercial native forests. Guava rust and myrtle rust combined would be highly damaging to our eucalyptus trees.
Importing goods
To keep guava rust out of Australia, never ignore Australia’s strict biosecurity rules.
The first sign of infection is tiny pustules on new growth, which erupt after a few days producing yellow spores.
The infected area spreads and pustules eventually merge.
Leaves, fruit and flower parts are susceptible, with dieback, stunted growth and plant death occurring over time.
Guava rust spores on leaves. Dr Silvaldo F. Silveira UENF, PaDIL.Badly infected leaves become deformed. Dr Juan A. Rocabado, UENF, PaDIL.
Where to look
Importers
Importation of infected plant material, including cut flowers, nursery stock and seeds is the most likely way that guava rust would make it to Australia. Spores can also be carried on timber, wood packaging and clothing, shoes, other personal effects and equipment.
Nursery owners, foresters and home gardeners
Look for dark spots, yellow pustules, deformed leaves and dieback on plants in the Myrtaceae family, which includes eucalypts, paper barks (melaleucas), bottle brushes (callistemons) and lilly pillies.
Campers and bushwalkers
Stay as clean as possible while in the bush.
Remove as much soil, organic matter and weed seeds as you can from:
clothing
footwear
tools and equipment
machinery
vehicles
backpacks
tent pegs
anything else that touches plants or the ground.
What to do
If you think you’ve found guava rust:
do not move samples
take a photo
contain the disease without disturbing it (this may be as simple as closing the doors on a shipping container).
