Farmers in Hawke's Bay, Canterbury and Marlborough are being urged to keep their eyes peeled for a notorious pasture pest that is just about to flower.
Regional biosecurity teams are conducting a Chilean needle grass awareness campaign as they try to get more of a handle on how widespread it is.
Environment Canterbury biosecurity advisor Laurence Smith said Chilean needle grass displaces other pasture species.
He said it is to spot most of the year but is about to flower, revealing its distinctive reddish purple seed heads.
Mr Smith said the awareness campaign is designed to help landowners identify and deal with the needle grass.