Biocontrol agent: Bridal Creeper Rust Fungus

Bridal Creeper Rust Fungus (Puccinia myrsiphylli) is an effective biocontrol for bridal creeper.

HOW THIS BIOCONTROL WORKS
Bridal creeper rust fungus was released in Australia in 2000 as a biocontrol for bridal creeper and is now considered to be a major ally in the fight against Bridal Creeper, as an effective and least toxic method of control. This fungus infects leaves and stems, reducing the amount of green plant material, absorbing nutrients from the plant, slowing plant development and reproduction and reducing the production of stems, fruit, rhizomes and tubers. Severely diseased plants shed infected leaves prematurely.

The rust fungus typically first appears on bridal creeper 1-2 months after the first autumn rains, spreading over winter and peaking in spring when the plant flowers and fruits. The fungus can produce many generations a year, resulting in large amounts of wind-dispersed spores. The rust produces “over-summering” hard-coated spores that survive in the absence of bridal creeper. Once rain returns in the autumn, these spores germinate and over its lifecycle, the rust fungus produces three additional types of spores, ultimately providing for infection and re-infection of bridal creeper plants after their re-emergence in autumn.  Continued cycles of new infections will occur as long as conditions for its germination are suitable. The rust can spread within and between bridal creeper infestations but will spread faster with intentional area rust releases.

WHY USE “RUST” AS A BRIDAL CREEPER CONTROL
Herbicides are the most effective method of control for bridal creeper. However, because bridal creeper often grows in areas of native vegetation, it is particularly important to avoid contact with desirable plants or soil near tree root zones. Off-target impacts can be of concern with herbicide applications. Application of a water-soluble spray made from the rust spores, commonly referred to as “spore-water”, provides an effective, simple and target-specific method of control of bridal creeper and is especially good way of infecting bridal creeper in areas of dense vegetation. The spray, delivered through standard spray units, is chemical free and harmless to everything except bridal creeper. Additionally, when bridal creeper rust is available, individuals can readily make their own ‘spore-water’.

For more information about Bridal Creeper, visit: www.agric.wa.gov.au/declared-plants/bridal-creeper-declared-pest