Bathurst bur... difficult to control.
Northland farmers are being urged to help destroy one of the region's nastiest weeds this summer - Bathurst bur.
Bathurst bur is a headache for sheep farmers in particular as the burs contaminate wool, downgrading the value of the fibre.
The burs can also damage shearing cutters and
combs and irritate the skin of shearers.
The spines can also damage the feet and skin of livestock while the seedlings are toxic to most livestock.
An annual plant which grows up to a metre tall, Bathurst bur is difficult to control because of the longevity of its seed, sometimes germinating several decades after a plant was last seen in an area.
"To successfully control this weed you must destroy the plant at this time of year before it can mature and form burs," Northland Regional Council biosecurity officer Peter Joynt said.
The seed germinates from November to February and mature plants are usually found in late summer.
The seedpod is readily carried and spread by animals, clothing and machinery.
The plant tends to grow in bare land and around troughs and gateways and because stock won't touch it, thickets usually spread unchecked.
It can be effectively controlled by grubbing or spraying prior to flowering and seeding.
"Any plants with burs must be removed and burned," Mr Joynt said.
The weed was most prevalent in the Kaipara region, with about 70 farmers having known problem spots and being visited by the council's biosecurity team annually to make sure they dealt to it accordingly.
Small pockets also existed around the Whangarei, mid north and far north areas.
"We have been dealing with it for about eight years and are gradually getting on top of it. We will eventually get it down to a very low level," Mr Joynt said.
Bathurst bur, believed to have arrived here from Australia early last century, was one of only three weeds landowners were required to get rid of, the others being Californian thistles and nodding thistles, he said.
