Bridal creeper is one of Australia's worst environmental weeds – but it is under attack from a creeping fungus.

CSIRO researchers in Western Australia are delighted with the progress of the biological control agent Puccinia myrsiphylli, a rust fungus which was first released at Floreat in WA in August 2000.

"The first release has caused extensive early leaf drop on bridal creeper at the site," says CSIRO's Kathryn Batchelor, who liases with community groups on the project.

"With releases over the past 12 months across 23 other sites, we're hopeful that similar results will be seen across large areas of bridal creeper infestations.

"We've been providing starter cultures to community groups, who are doing a fantastic job helping CSIRO distribute the fungus", she says.

The rust works by infecting the leaves of the weed, causing localised yellowing of leaf tissue, and reducing the plant's ability to convert sunlight into energy. This forces the plant to divert nutrients to the infection site, reducing plant vigour and disrupting the flowering and fruiting processes.

The rust is active on bridal creeper from April/May through to November.

It can survive through the dry hot conditions of summer as a hard-coated spore. The spores are wind borne, but its dispersal can be hastened by transferring infected foliage from one infestation to another by hand.

"The majority of the plant is underground in the form of dense tuber mats", says Tim Woodburn, the project leader in WA.

"By reducing photosynthesis due to yellowing of the leaves, coupled with early leaf drop, the reserves that the plant are able to divert to the tubers are greatly reduced.

"But biological control agents are not 'silver bullets' and will work best when they are part of an integrated approach to bridal creeper control."

In the Year of the Volunteer, Weedbuster Week activities are focusing on Local Heroes – Global Champions.

"This is fitting for our work," explains Ms Batchelor, "as much of the success of our biological control agents is due to the community becoming involved and helping us distribute the agents as widely as possible."

Bridal creeper, Asparagus asparagoides, is an environmental weed found in every state across southern Australia. It is considered the major threat to biodiversity in southern temperate forest/woodland ecosystems. The weed's tuber mats and foliage make it very difficult for native vegetation to germinate and establish.

Introduced from South Africa in the 1850s as an ornamental plant, it is now out of control, smothering vast areas of natural bushland. It has been declared one of the 20 Weeds of National Significance (WONS).

Researchers from CSIRO are joining in Weedbuster Week which runs between 7-14 October, with activities in all states.

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