Plant biosecurity guards against the risks of new outbreaks of pests, diseases and weeds at the Melbourne and Cranbourne Gardens.

Prevention rather than cure is the aim of plant biosecurity as many diseases can only be controlled to a limited extent and often are never eliminated. It is also vital that any existing pests are not transported from Melbourne or Cranbourne Gardens, causing problems for other gardens, agriculture and natural habitats.

The Royal Botanic Gardens has a Biosecurity Policy and a Weed Strategic Plan to provide principles and practices that can reduce the risk of new pests being introduced to its landscape or of known pests leaving the Gardens.

You can help!

When visiting the gardens please do not bring plant material on site, please don’t walk on the garden beds and don’t take any cuttings. This is how diseases are spread to and from the Gardens – and you might get a fine too.

Myrtle Rust

One of the most recent reminders of the the imporance of biosecurity was the oubreak of Myrtle Rust (Uredo rangelii) in Victoria in 2012. Myrtle Rust is a serious fungal disease affecting the plant family Myrtaceae, which includes many Australian natives commonly found in Victorian gardens and parklands. Myrtle Rust attacks new growth and causes the affected plant tissue to die back. It presents as yellow flecks and there is no easy treatment or cure. Its growth can be partially suppressed by the use of registered fungicides, but with no effective cure.

Myrtle Rust was widespread on the eastern seaboard of New South Wales (NSW) and in south-east Queensland, on over 150 properties and 150 Myrtaceae species of plants. Locations range from commercial plant nurseries, public gardens, parks and streetscapes to large areas of bushland. Under the right conditions, Myrtle Rust may slow regeneration of native forests after harvesting or bushfire and could, in extreme circumstances, change forest biodiversity.

Since early 2012, plant surveillance has been increased significantly at both Melbourne and Cranbourne Gardens, with a concerted focus on monitoring of ‘sentinel plants’, that is, plants that have been identified as particularly susceptible to Myrtle Rust. At RBG Melbourne, this includes landmark River Red Gums near Ornamental Lake and on Princes Lawn. Sentinel plants are checked during regular inspections by the Horticulture team, as are susceptible plants in high-traffic areas such as the Children’s Garden at Melbourne and the Australian Garden at Cranbourne.

Some facts about Myrtle Rust

Which plants are affected?

All members of the Myrtaceae plant family are potential hosts of Myrtle Rust. The family includes:

  • gum trees (Eucalyptus)
  • bottlebrush (Callistemon, Melaleuca)
  • tea tree (Leptospermum)
  • lilly pilly (Syzygium, Acmena, Waterhousea)
  • paperbark (Melaleuca)
  • myrtle (Backhousia)
  • guava (Psidium)
  • midyim (Austromyrtus)
  • rose apple (Syzygium)
  • brush box (Lophostemon)
  • New Zealand Christmas bush (Metrosideros).

How does it spread?

Rusts are highly transportable because they can produce large numbers of very small spores. Myrtle Rust can be dispersed by:

  • movement of infected plant material (e.g. nursery stock, cut flowers, plant cuttings, germplasm)
  • movement of contaminated equipment (e.g. secateurs, chainsaws)
  • wind, water (wind-driven rain, irrigation) and gravity
  • animals (e.g. insects including bees, birds, other wildlife, pets)
  • humans (e.g. on clothing, shoes and jewellery)
  • vehicles

For further information on Myrtle Rust visit