Biocontrol of Fleabane - impact assessment on related species

CSIRO is currently researching biological control options for flaxleaf fleabane (Conyza bonariensis), which is an invasive weed of agricultural importance in both cotton and grains where it appears it is developing herbicide resistance and a weed of plant production systems including production nurseries. As part of this project CSIRO are in the preliminary stages of investigating if biological control options for Canadian fleabane (Conyza canadensis) and Tall fleabane (Conyza sumatrensis) is desired as these species also seem to be becoming problematic in agriculture/horticulture.

Of important to nursery production is the potential impact of a biocontrol agent on related plant species to the above, such as Erigeron karvinskianus, therefore GIA will be providing information to CSIRO on these commercial species for inclusion in the biocontrol assessment.

GIA notes the following:
  • GIA supports, in principle, the introduction of biological organisms to control the two listed Conyza spp. in the CSIRO nomination document plus Conyza bonariensis.
  • Fleabane is a weed of nursery production and is listed in numerous industry pest management guides therefore management strategies for this weed are supported.
  • GIA agrees with the nomination document’s assessment of Erigeron karvinskianus being the dominant commercially traded species that is related to the listed Conyza spp.
  • GIA is advising CSIRO of another cultivar Erigeron glaucus x Wayne Roderick Daisy “traded as Wayne Roderick Daisy that is commercially relevant.

An important step before biological control research of an invasive plant goes ahead is for the plant species to be approved/endorsed as a target for biological control by the Environmental Invasive Plant Committee. To assist the committee with its assessment, CSIRO have been asked to engage with key stakeholders such as Greenlife Industry Australia to ensure there are no conflicts of interest/unintended impacts should any biological control agent(s) be released for these two species (Conyza bonariensis has already been nominated by the committee).

Please contact National Biosecurity Manager John McDonald via email ( if you have any other commercially traded related species to nominate.

Developed by the NGIA National Nursery Industry Biosecurity Program Team 2019