Farmers in Western Australia’s grainbelt can try out a new tool to control skeleton weed this summer, by accessing a tiny midge that feeds on the pest plant.
The Department of Primary Industries and Regional Development (DPIRD) wants to hear from farmers interested in distributing skeleton weed gall midge, Cystiphora schmidti, onto infested paddocks.
Skeleton weed is a fast-spreading invasive weed that can cause grain crop yield losses and increase grower costs.
DPIRD project officer Kate Detchon said a natural, host-specific enemy like gall midge offered an additional option to combat skeleton weed.
“Biocontrol will not replace chemical methods for eradication but can add to the integrated weed management toolkit,” Ms Detchon said.
“DPIRD has been testing the establishment of the gall midge in WA, as part of a joint project with CSIRO, Australia’s national science agency.
“Trial sites in Narembeen have shown good establishment of the midge at several sites. The gall midge appears to be having an impact on skeleton weed, including leaf loss in winter rosettes and stem and tip dieback now starting to occur one year after the insects were released.”
Ms Detchon said gall midge has been used in eastern Australia since the 1970s, where it has been proven to only affect skeleton weed and not attack other plants.
DPIRD has bred the gall midge at its facilities in Albany and Moora, which are now ready for release during summer when the natural predators have the best chance of establishing on skeleton weed plants.
“We ask farmers, particularly in the Narembeen and Yilgarn areas, who want to access the gall midge to contact us, so we can discuss whether their property is suitable as a release site,” Ms Detchon said. “This is a limited release which runs until March 2025.”
The gall midge releases will be done by DPIRD officers, who place gall-infested leaf material into the paddock, where the gall midge adults will hatch and lay eggs inside the skeleton weed plants in the paddock.
Protocols for the release of the gall midge have been developed to minimise the risk of skeleton weed spreading at the release sites.
Gall midge has a life cycle of several weeks, with adults emerging primarily in spring and summer when skeleton weed is most abundant.
Females lay between 60 to 180 eggs each on leaves and stems of the skeleton weed plant. The larvae hatch and feed within the plant, forming purple and green galls.
When galls are abundant, infested leaves and stems die off, which can stunt plant growth and reduce flowering, seed production and root reserves.
The project is part of the broader Skeleton Weed Program, which is supported through the grower-funded Grains, Seeds and Hay Industry Funding Scheme.
Under the State’s Biosecurity and Agriculture Management Act, skeleton weed is declared as an eradication target for the whole State, except in the Narembeen and Yilgarn Shires where it is under a management declaration.
Growers interested in accessing gall midge can contact DPIRD senior research officer John Moore on 0437 353 640 or john.moore@dpird.wa.gov.au
More information on skeleton weed control in WA is available from the DPIRD website.
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