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Two unique dogs are strengthening the Northern Territory’s rigorous biosecurity defences.

Zacc and Scout have been trained to sniff out citrus canker, a highly contagious bacterial disease that is a serious threat to Australia’s citrus industry. Thanks to industry and public support, the NT Government has recently led a successful eradication program, securing proof of freedom from the disease in April.

The NT has a formidable shield against destructive pests and diseases, with teams of biosecurity experts and world-class scientists based at the Territory Government’s Berrimah Farm Science Precinct and Charles Darwin University. Bron Mullins, who runs her company, Top End Conservation Dogs, from a rural block on the outskirts of Darwin, trains the scent-seeking canines.  In addition to the super noses of Zacc and Scout, a third beagle kelpie cross, Ryker, is a new puppy recruit in training.

A dog’s sense of smell is at least 10,000 times stronger than a human – and in some breeds, up to 100,000 times stronger. Bron’s dogs were trained to sniff out citrus canker after Charles Darwin University scientists created a synthetic scent that mimics the “volatiles” the bacteria emits when under attack from the disease. University chemists spent six months working with the Department of Industry, Tourism and Trade’s Biosecurity and Animal Welfare project scientist, Alex Fulton, to sample and analyse the volatiles from infected citrus plants and the bacteria.

“Detector dogs can potentially discover the disease earlier than humans, including before the symptoms are visible, and also search larger areas like orchards,” says Ms Fulton. Bron says: “Everything gives off a scent and dogs can be trained to sniff out anything.” Zacc and Scout have also been trained to detect Siam weed, ranked as one of the world’s most invasive plants. It takes six to eight weeks to train a rookie detection dog, but only one to two weeks for experienced animals.

“Dogs are a fantastic biosecurity weapon,” says Bron.

“They save a huge amount of man hours and are more efficient.” Ms Fulton says: “This has several advantages for plant pest and disease programs as we can stop the spread earlier, potentially saving destruction of larger cropping areas. “We can also have greater confidence that the pest or disease is absent after treatment or removal activities have taken place.”

The department partnered with the Australian Government to deliver the $260,000 project. The department’s Chief Plant Health Officer, Dr Anne Walters, says the collaboration with Charles Darwin University chemists has laid the groundwork for future artificial lure detection projects. “The focus on local expertise and solutions is important when protecting a multimillion-dollar industry,” she says. “The knowledge gained from this project could be put to use in the future, detecting other biosecurity threats in the Northern Territory and helping the NT to respond rapidly to pests and diseases when they are detected.”