Red imported fire ants have re-infested organic farms in Queensland, leaving them without options to control the pest for 14 months.
Treatment was suspended in August last year on some export-certified properties in the south-east Queensland suppression zone after genetically modified ingredients were identified in baits used on nests.
The National Fire Ant Eradication Program confirmed parts of a 1,110-hectare zone spanning the Lockyer Valley, Scenic Rim and Somerset agricultural hubs were re-infested, though the extent is yet to be determined.
Fire ants can fly up to five kilometres, making their spread difficult to control.
"We do have evidence of reinfestation of areas from properties that haven't been treated [since the suspension]," senior director of operations Robbie Wilson said.
The genetically modified ingredients found in fire ant bait cannot be used on organic farms. (Supplied: Johan Augustin)
He acknowledged organic farmers could not use ant-killing bait containing genetically modified (GM) corn and oil without risking their organic status.
"The organic producers … are certainly not objecting to eradication of fire ants but they have an interest in maintaining their accreditation for their livelihood,"
he said.
"We've been working with (peak body) Australian Organic Limited … about how we support them in the eradication and limitations of infestation, which has been quite positive."
Mr Wilson said the affected areas made up a small part of the 30,000 hectares identified as having gaps in treatment across the wider control area.
"But that treatment may already be scheduled," he said.
He said approving a treatment suitable for organic farmers was the "first phase" of bringing those properties back into the eradication program, which aims to eliminate fire ants by 2032.
Treatment option found
On Monday, the federal Department of Agriculture, Fisheries and Forestry announced it had granted a permit for a product using concentrated cinnamaldehyde, the organic compound that gives cinnamon its flavour and odour, for use in Queensland.
"This treatment product has been assessed as compliant with the National Standard for Organic and Bio-Dynamic Produce," the department said.
The tiny fire ants spread quickly and are easy to overlook. (Supplied: National Fire Ant Eradication Program)
The permit requires application "by direct nest injection and/or as a nest drench" by people authorised by the NFAEP.
Mr Wilson said the first shipment of the product from New Zealand was awaiting customs clearance at Brisbane port.
"It is an organic product that can be used on certified organic properties," he said.
Organic farmer Di Fyson welcomed the new treatment option. (Supplied: Di Fyson)
But the labour-intensive method could not replace broadscale baiting, which Mr Wilson said authorities continued to work on for larger organic operations.
Scenic Rim organic farmer Di Fyson welcomed the new treatment, but questioned why it took so long.
"If cinnamon oil has been an option all along, why have we had this pause in treatment when it's such a serious problem?"
she said.
Ms Fyson, who grows domestically certified organic leafy greens and pumpkins, received treatments during the suspension.
But she said she would be willing to try the new product.
"Definitely, particularly if that's going to be the only option," she said.
Reece Pianta, advocacy director at the Invasive Species Council, which lobbies for better funding for eradication and prevention programs, said he was concerned that substitute treatments were taking too long to deploy "at mass scale."
"I'm concerned about the lack of organic farm treatment alternatives creating gaps in fire ant eradication," he said.
"We know from past experience when there have been gaps in fire ant treatments, that is when fire ants have spread."
"The success of eradication is reliant on keeping those treatment gaps closed."