Daisy may look like a normal pup but she is saving dozens of native plant species

This weed, which creeps along dirt floors before growing to more than one metre tall, can smother native plants, reduce shelter for animals and compete with food crops. And it is notoriously hard to get rid of.

"There is human error. We might think we have eradicated this weed or treated it effectively but because of small seedlings growing in amongst dense vegetation, we are never quite sure," Lake Macquarie's natural assets coordinator Dominic Edmonds said.

But now, two sniffer dogs are solving the problem.

Daisy the cocker spaniel and Henry the border collie have been trained to sniff out the violet, eliminating even the smallest of seedlings.

Their work was led by a team at Indago Environmental, who used similar techniques to that of security sniffer dogs when training the clever canines. These include scent cones, which excrete the odor produced by Chinese violets.

Indago director Naiomi Finlayson said despite a gruelling training process, the pay-off was worth it for a healthier Lake Macquarie environment.

"It's a really rewarding process based on small steps and easy wins. The time it takes really depends on the target odour and the complexity of environments where the scent is found," she said.

"Learning to find a tiny Chinese violet seedling in dense undergrowth takes longer, for example, than teaching the dogs to find koala or fox scat, which is a much faster process."

The introduction of Daisy and Henry to the team comes just at the right time.

Chinese violet used to only be found in pockets of Lake Macquarie, Newcastle and Port Stephens, but some isolated growth has started on the Central Coast and in Maitland, Kempsey and Tweed.

If the weed spreads further - particularly into the Upper Hunter and New England areas - it could damage crops.

"At the moment, [the weed] is fairly restricted so we have an opportunity jump on it, to nip it in the bud, so it's not getting out and impacting the rest of the state," Mr Edmonds said.

"Dogs have been used in a lot of other weeds throughout the country and the state but this is a first for Chinese violet," he said. "The dogs give us a special ability to increase detectability."

Once the violet is found, humans can eradicate it through marking and check-ups.

"We would then GPS mark the location so we have a record of where p[the weed was found. We can keep coming back to where it is and determine whether or not the eradication treatments were effective," Mr Edmonds said.

The project is jointly funded by council and the NSW Government's local land services.

"The program has really been reliant on the goodwill of Indago and I think that's important," Mr Edmonds said. "They, so far, have been training up their two dogs free of charge. It's really providing a huge benefit."