Canterbury Regional Council has confirmed a new outbreak of Chilean needle grass, which it is trying to contain.
Chilean needle grass is a major plant pest for hill country farmers, especially in Marlborough and Hawke's Bay.
It was first found in North Canterbury at Spotswood in 2008. It's now been confirmed on a property in the Hurunui district.
The regional council says it's been found growing on a third of the 500 hectare property and must have been there for some time.
Biosecurity advisor Laurence Smith says the council is working with the land owner to make sure the outbreak does not spread any further.
Neighbouring properties are also being checked.
Chilean needle grass is spread by stock movement, machinery, crops and feed, and people.
It's a tufted perennial plant which can grow up to 1 metre high.
Its leaves are bright green and harsh to touch. The flowers have a purple tinge and ripen into hard, sharp seeds along with twisting tails.