Australian landowners engage new biological control agents for problem weeds

A global network of the world’s top researchers has significantly advanced weed management in Australia.

Some of Australia’s most damaging and destructive weeds are under fire from a legion of natural enemies from around the world, as the second phase of the AgriFutures Australia project, Underpinning agricultural productivity and biosecurity by weed biological control, comes to a close.

This project is one of the projects within the Rural R&D for Profit program and is primarily focussed on identifying and releasing biological control agents for weeds.

The impact of weeds on the Australian economy has been estimated to cost up to $5 billion per year through reduced profitability and productivity of agricultural land, choking of our waterways and requiring the ongoing use of herbicides and other controls. There are also substantial environmental costs.

Australian landowners now have access to new biocontrol agents to manage some of the most damaging weeds, which affect 23 million hectares of profitable land and 15,000km of water resources. 11 weeds have been targeted for biological control, over a seven year, two phase project.

Researchers from the CSIRO, Agriculture Victoria (AgVic), Queensland Department of Agriculture and Fisheries (QDAF) and the NSW Department of Primary Industries (NSW DPI) have collaborated with counterparts across the globe to conduct native range surveys and identify potential biocontrol agents for importation into Australian quarantine. A truly global project, Australian researchers have scoured the world, with work being undertaken on every continent (excluding Antarctica) in partnership with colleagues from as far as Iran, Ethiopia, Paraguay and many other countries.

The process for establishing a biocontrol agent in Australia is lengthy, with rigorous testing and regulatory compliance needed. On average, the time from identifying a potential biocontrol agent to its mass-release in Australia can take from five to 10 years.

Biological control involves the identification of an insect, arthropod or pathogen from the native range available, which will attack a specific weed, reducing its ability to spread. Research ensures non-target species are not harmed by the biological control agent. This sustainable approach requires little further investment after suitable agents are identified and established, enhancing Australia’s agricultural competitiveness on a global stage.

At least six of the weed targets now have a biological agent undergoing mass or trial release programs including:

• African boxthorn – A biocontrol rust fungus agent, has been deemed safe for release in Australia. Pilot release program for the rust during the 22/23 summer across SE Australia has shown that the rust can establish on African boxthorn in the Australian environment.
• Flaxleaf fleabane – A rust fungus (Puccinia cnici-oleracei) biological control agent, has been deemed safe for release in Australia with a trial program underway across key grain growing areas across Australia.
• Cabomba – After years of rigorous research in South America and Australia, scientists have released cabomba’s natural enemy, a weevil (Hydrotimetes natans), into Lake Kurwongbah, managed by Seqwater, north of Brisbane. If successful, the weevil will be the first release of a biocontrol agent against cabomba anywhere in the world and will significantly improve water holding capacity of dams and reduce the cost of treating drinking water.
• Hudson pear – A mass-rearing facility for a cochineal insect (Dactylopius tomentosus ‘californica var. parkeri’ lineage) has been established at Lightning Ridge, NSW. The agent has and continues to be released on a large scale with the help of landholders in the region and monitoring indicates a significant impact on the growth and survival of Hudson pear.
• Prickly acacia – Targeted releases of a thrips species (Acaciothrips ebneri) are underway in north Queensland which will hopefully reduce establishment and ultimately impact of prickly acacia across cattle properties. After the strategic targeted releases, the agent will be released more widely and be available for producers in the region.
• Sagittaria – Following rigorous studies in the USA and in an Australian quarantine facility, a fruit-feeding weevil has been approved for release. It is now being mass-reared for releases throughout infested waterways and irrigation channels in Victoria and New South Wales.

To streamline future biocontrol programs, this project has also worked to develop a better methodology to determine biological risk in the future. This will ensure that decision making becomes more transparent, leading to more efficient biocontrol projects.

Although not yet ready for release, significant progress has been made in identifying biological control agents for damaging weeds including Koster’s curse, Navua sedge, African lovegrass, giant rat’s tail grass, silverleaf nightshade and saffron thistle.

According to Dr Alex Ball, project coordinator, AgriFutures Australia, the outcomes of this project are set to benefit all Australians.

“Once established, biological control agents will begin to reduce weed impact on sheep and cattle grazing properties, cropping, public lands and irrigation channels improving the productivity, profitability and sustainability of Australian agriculture.

“In turn, all Australians will benefit from a more productive agricultural industry, shoring up Australian’s international competitive position”.

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This project is supported by funding from the Australian Government Department of Agriculture, Fisheries and Forestry as part of its Rural R&D for Profit program, research and development corporations, commercial companies, CSIRO, state departments and universities.
Partner organisations include: Australian Government Department of Agriculture, Fisheries and Forestry, AgriFutures Australia, Grains Research and Development Corporation (GRDC), CSIRO, NSW Department of Primary Industries, Department of Agricultures and Fisheries QLD, Agriculture Victoria, Bundaberg Regional Council, Gympie Regional Council, HQ Plantation Pty Ltd, Hinchinbrook Shire Council, NSW Environmental Trust, NSW Weed Biocontrol Taskforce, SEQWater, Tablelands Regional Council, Cassowary Coast Regional Council, AgForce Farmers QLD, Castlereagh Macquarie County Council, Hudson Pear Taskforce, Landcare Research, Tablelands Regional Council, Cassowary Coast Regional Council, USDA, University of Texas, FuEDI (Argentina), TasWeeds, Manaaki Whenua — Landcare Research New Zealand.