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1990 - 2005
Biological Control of Scotch Thistle and Paterson's Curse

Between 1990 and 2005, CSIRO entomologists tested the use of insects (biocontrol agents) to control the occurrence of the declared noxious weeds, Scotch Thistle (Onopordum acanthium) and Paterson's Curse (Echium plantagineum). HMLG collaborated with CSIRO in their early trials with 130 releases occurring in the Harden Shire. Growers in the district assisted with the releases by monitoring and managing the biocontrol agents, particularly the agent for controlling thistles.

The insects had a measurable impact on the weeds and early results had growers enthusiastic about the potential benefits, including the ability to reduce herbicide use.

Biocontrol is now widespread across Harden with biocontrol agents surviving and thriving


Biocontrol, together with grazing management and timely chemical application, have greatly reduced the impact of Scotch Thistle and Paterson’s Curse across our region.


Incidentally, the collaboration between CSIRO and HMLG provided an excellent model for community involvement in biological control. The partnership facilitated a more rapid resolution of problems associated with these weed species in many ways, such as by:

  • setting up a network of over 100 graziers involved in the project and integrating biological control into their pasture management regimes;

  • developing a close working relationship between CSIRO and HMLG to train landholders in biological and integrated weed control;

  • providing 40 nursery sites for the establishment of biological control agents;

  • holding weed control training workshops, talks, interviews and field days; and

  • helping producers better understand the ecology of weeds in a farming system.

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