Canterbury dogs trained to sniff out Chilean needle grass in world first

In a world first, two Canterbury dogs have been trained to sniff out Chilean needle grass, a plant that threatens livestock and crops.

With a great sense of smell at just three years old, they are the only dogs in the world who can detect the grass in a field of other grasses.

"It's just phenomenal, their sense of smell ... that's why we use them because for humans it's really hard to find," says plant scientist Fiona Thompson.

New Zealand saw a shocking infestation of the weed in Marlborough and it could be spread to 15 million acres if it isn't checked.

"Chilean needle grass is another pest that's slowly invading Canterbury," says Lawrence Smith from Environment Canterbury.

Chilean needle grass can affect pasture and the sharp seeds can cause blindness, deafness and can travel on sheep wool.