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Weeds: a widespread problem

Wandering trad (Tradescantia fluminensis) is a herbaceous groundcover native to South America that has become a significant environmental weed of temperate regions of Australia, with hotspots of invasion in moist forests of eastern NSW, south east Queensland and the Dandenong Ranges region of Victoria.

We are all affected by weeds, and not only through their unwanted presence in our backyards.

Weeds – alien or native plants that grow where they are not wanted - are a major threat to both the natural environment and agricultural land we depend on. They can also directly affect the health and well-being of communities across Australia.

Weeds can upend ecological communities, adversely affect rivers, rangelands and forest systems, compete with crops, harm livestock, contaminate produce, reduce water quality and cause human health problems such as asthma.

They are Australia’s most economically destructive type of invasive species. They have cost our economy more than $150 billion over the last 60 years, and continue to cost it around $5 billion per year.

Grain growers alone spend more than $2.5 billion per year on weed control.

A new species of weed takes root in Australia on average every 18 days. All up, more than 3200 introduced plant species are now established in Australia.

We need safe, cost-effective and sustainable methods for weed control to reduce these negative impacts.

[Music plays and an image appears of a waterfall and the camera gradually zooms in and text appears: The natural environment that we enjoy in New South Wales is under continuous threat from invasive weeds…]

[Image changes to show a valley floor filled with ferns and wandering trad and text appears: … such as groundcover wandering trad…]

[Image changes to show a close view of orange fruit on a climber leaf cactus and text appears: … the climber leaf cactus…]

[Image changes to show a patch of flowering smothering ox-eye daisy amongst some trees and text appears: …the smothering ox-eye daisy…]

[Image changes to show a close view of an African boxthorn shrub and text appears: … the thorny shrub African boxthorn…]

[Image changes to show a sea spurge plant on a sand dune and text appears: … and the beach invader sea spurge]

[Image changes to show broad-leaved pepper tree thrips crawling up a succulent leaf and text appears: Broad-leaved pepper tree thrips, To identify safe biological control agents, promising insects…]

[Image changes to show a close view of Balloon vine rust fungus on the back of a leaf and text appears: … or fungi that attack the weeds in their countries of origin…]

[Image changes to show two people dressed in white protective overalls, caps and gloves working on potted plants and text appears: … are imported for rigorous risk assessment in quarantine facilities]

[Image changes to show two males using long tongs and walking between shelves, placing prickly plants into plastic containers on the shelves and text appears: Mass-rearing of cochineal on Hudson pear, Once approved for release, agents are mass-reared and distributed]

[Image changes to show a male looking out over a patch o Crofton weed and text appears: Rust fungus defoliating Crofton weed, Suppression of weeds by biological control…]

[Image changes to show a view looking over the ocean and text appears: … benefits biodiversity and ecosystems]

[Image changes to show the NSW Government and CSIRO logo and text appears: Want to learn more?, Visit, Research supported by co-investments from CSIRO and the NSW Government through its Environmental Trust, NSW Department of Primary Industries and NSW Department of Planning, Industry and Environment]

[Music plays and the CSIRO logo and text appears: Australia’s innovation catalyst]

This video descibes biocontrol work we are doing with the NSWm government.

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Biocontrol to manage weed impacts

Traditional weed control typically involves either the physical removal of the weed or the use of herbicides.

A different, sustainable approach - and CSIRO’s area of expertise - is weed biocontrol. Weed biocontrol utilises a weed’s specialist natural enemies, like insects and fungi, to reduce the weed’s impact.

Termed biocontrol agents, these natural enemies reduce weed biomass, reproduction and/or population density. They are also self-sustaining, making them an effective method for long-term weed control.

Extensive research is undertaken to ensure that only biocontrol agents that don’t threaten desirable non-target species are used.

Our work in weed biocontrol
Diver covered in Cabomba. Cabomba (Cabomba caroliniana) is a submerged aquatic weed of permanent and slow moving water bodies; it affects water quality, recreational activities and public safety, and aquatic biodiversity.

CSIRO scientists have been doing research on biocontrol of weeds since the 1920s. Working with government, industries and communities, our weed biocontrol programs involve:

  • Quantifying the impact of targeted weeds in Australia-Investigating the genetic structure of the weeds and identifying their origin in the native range
  • Surveying for natural enemies in the native range and selecting promising candidate biocontrol agents
  • Demonstrating that the candidate agents are safe and obtaining approval from the authorities for their introduction in Australia
  • Releasing and evaluating the efficacy of biocontrol agents in controlling the target weeds and the flow-on indirect benefits to ecosystems.

CSIRO has many active biocontrol projects underway for both temperate and tropical weeds of importance to Australia.

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