In Florida, the pathogen has been considered as a biological control agent for the invasive Australian plant, Melaleuca quinquenervia.

If left unchecked, it will cause of the most serious threats to the integrity of the native ecosystem, turning marshes in the Everglades into swamps.

[7][8] With Autropuccinia psidii, the disease has the ability to disperse inoculum rapidly and attack healthy tissues, causing substantial damage to their hosts.

[6] Austropuccinia psidii can rapidly spread globally and can impact commercially and ecologically important species of Myrtaeceae such as Archirhodomyrtus beckleri, Decaspermum humile, Gossia hillii and Rhodamnia maideniana, that are extremely important in Australia affecting their native forest ecosystems and causing extinctions.

[10] This fungus is a serious problem because of its ability to spread rapidly from its production of a large number of small spores that can be easily dispersed over long distances by wind.

Infection from Autropuccinia psidii results in significant changes to the structure, composition, and the function of forests trees on a landscape level.

[3] Initially, the disease appears as small purple or red brown flecks with a faint chlorotic halo on the leaf surface, which coalesce to form bright yellow pustules.

[3] Myrtle rust also makes plants more susceptible to secondary infections, which may occur within days of the initial appearance of the pustules.

[5] Favourable conditions that increase the infection rate include: new tissue; high humidity; free water on plant surface for more than 6 hours; moderate temperatures, around 15–25 °C.

[15] Myrtle rust may remain on a single host plant to complete its life cycle, which can be as short as 10–14 days.

However currently, the major threat of Puccinia in Hawaii is the massive damage it is doing to Eugenia koolauensis, a federally listed endangered species.

In January 2012, an isolated myrtle rust outbreak was reported in Victoria[20] beginning in Melbourne's southern and eastern suburbs.

In Australia, the family Myrtaceae - which includes eucalypts, melaleuca and lilly pilly - is diverse, widespread and important to many native ecosystems.

Myrtle rust grows in shoots, fruits and flowers, destroying the food relied on by some species of flying foxes, lorikeets and honey eaters.

[29] Rust fungi typically have complex life cycles that include stages of sexual and asexual reproduction that occasionally occur on phylogenetically distinct host plants.

In Stage II, the production of urediniospores go back to inoculate young leaf/shoot/fruit/flower bud, important for secondary infection and contributing to the polycyclic nature of the pathogen.

After the penetration of urediniospores by a combination of extracellular secretions and physical force, the germ tube is formed and elongated in a favorable area fueled by spore protein reserves from an appressorium.

The Australian Government, through the Department of Agriculture Fisheries and Forestry, established the Myrtle Rust Coordination Group to manage the investment of $1.5 million of research funding.

[28] Practical measures to minimise the risk of increasing the distribution of myrtle rust include: not moving plant matter from one site to another; minimising pathogen spread by arriving and leaving each site clean of the pathogen, and avoiding areas that may contain myrtle rust-infected plant matter.