Biosecurity officers have a new weapon in their bid to stop the spread of Chilean Needle Grass.
The invasive weed is causing a headache for Canterbury farmers, but detector dogs have been specially trained to hunt it out.
And now new recruits Tahi and Nala are joining the fight to stop its spread.
The invasive weed smothers pasture and produces seed heads that can drill into animal's skin, causing painful wounds. It was first found in Canterbury nines years ago and has since been found on 20 properties.
Environment Canterbury biosecurity advisor Laurence Smith says the dogs are really helpful.
"They're going to find that grass in a grass that nobody else can so, it's fantastic."
Both Tahi and Nala were rescue dogs, and have spent the past few months learning to search out the scent of Chilean Needle Grass.
So what's the reward for discovering the pesky weed along this road side in Cheviot? A dried snack.
But Mr Smith says the potential reward from the dogs' work for the region could be far larger.
"The dogs give us a huge opportunity to detect pests - not only Chilean needle grass, but other pests - when they're not that easy to find."
This gives biosecurity officials and Canterbury farmers a fighting chance in their battle against this foreign invader.