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New biocontrol agent for Crofton weed already impresses

Article provided by Dr Louise Morin, CSIRO Health & Biosecurity

 Crofton weed (Ageratina adenophora) is found in several areas along the NSW coast and in south-east Queensland. It produces copious quantities of windborne seeds, spreads rapidly and once established at a site reduces its agricultural or ecological value. Following extensive testing, the rust fungus Baeodromus eupatorii (ex. Mexico) was approved in May 2014 for release in Australia for the biocontrol of Crofton weed. It infects young leaves and stems of Crofton weed. It was first released at a handful of sites on the NSW South Coast in winter-spring 2014. Within 6–12 months of these releases, the rust fungus had caused extensive defoliation of Crofton weed and naturally spread to nearby Crofton weed infestations (in one case up to 15 kilometres away from the release site).

In partnership with the community, a large-scale release program of this new biocontrol agent was initiated across NSW in autumn 2015 with financial support from the Weeds Action Program (WAP) of the NSW Department of Primary Industries. The fungus was also released in 2015 at 11 sites in national parks in south-east Queensland with support from the Queensland Parks and Wildlife Service.

The community-based release program in NSW is continuing in 2016 with support from the NSW Environmental Trust. Rust-infected potted plants, grown either in pasteurised soil or in rock wool, are distributed to managers of private or public land at field events or via the post. Managers are provided with simple guidelines on how to make the release and monitor establishment and spread of the agent, and are expected to provide feedback. The potential gains from this biocontrol agent for land managers far outweigh the efforts (albeit limited) required to make a release and monitor outcomes.

As part of the WAP project in 2015, 336 rust-infected Crofton weed plants were produced and distributed to land managers. A total of 81 releases (each involving a minimum of 4 rust-infected plants) were made at different sites. Details of release sites, especially coordinates, were obtained for 94% of the releases made. Post-release feedback was obtained from 88% of the participants, with the agent confirmed established at 79% of the sites monitored. The maximum natural spread of the agent within ca. 1 and 6 months after a release was 5 and 250 metres, respectively.

The partnership with land managers and community groups from different regions of NSW is enabling the new biocontrol agent to be cost-effectively released at several locations across the entire range of Crofton weed in NSW. All signs so far are that this new agent will provide a sustainable tool to reduce populations of Crofton weed. Continued infection of foliage by the agent should considerably reduce flowering in Crofton weed and thus the quantity of wind-borne seed produced. Such reduction in reproduction will decrease likelihoods of new Crofton weed infestations establishing.

For more information on this biocontrol release program click here

or visit http://www.csiro.au/ [enter crofton weed rust fungus in search box].
If you are interested in participating in the release program contact:
CSIRO Health & Biosecurity, Canberra
Dr Louise Morin, Tel: (02) 6246 4355, This email address is being protected from spambots. You need JavaScript enabled to view it.
Mr John Lester, Tel: (02) 6246 4325, This email address is being protected from spambots. You need JavaScript enabled to view it.
The underpinning research on the Crofton weed rust was supported by the Australian Government through the Rural Industries Research & Development Corporation, the Lord Howe Island Board and the Office of Environment and Heritage NSW.

Local Land Services - North Coast

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