War declared on vine pest

By ROSALEEN MacBRAYNE

An aggressive vine, officially recorded only once before in New Zealand, is spreading its tentacles through the Bay of Plenty.

The kudzu plant, a costly pest in the United States, has taken root in at least three places.

The largest infestation, at rural Pahoia near Tauranga, was identified recently. The creeper has spread from roadside to neighbouring pasture and has already smothered 3000sq m of shrubs and trees, including a 15m-high pine.

A second area of 1000sq m is alongside State Highway 2 near Te Puke, and a smaller one in a Matata garden has been controlled.

The only other naturalised site of kudzu, a climbing or trailing perennial of the legume family, was in a North Auckland coastal area some years ago.

The vine, identified by the National Herbarium in Lincoln, has dark green leaves, large tuberous roots and elongated purple flowers with a fragrance reminiscent of grapes.

Environment Bay of Plenty's plant pest coordinator, John Mather, says the vine is extremely vigorous, with stems able to grow up to 30m in a season.

Kudzu is known for its resistance to herbicide - one product made it grow better, while others have had little effect. Even with repeated herbicide treatment, some vines take 10 years to kill.

Mr Mather does not know how the prohibited plant came into the Bay of Plenty but says the regional council is studying a variety of eradication methods. Residents have been asked to report any sightings of the invader.

"We are going to do our very best to get rid of this plant pest. We do not want to let it get out of control like in the United States," he said.

A native of Japan and China, kudzu grows too well in the southeastern United States, where it was introduced at the turn of the last century for use as a soil stabiliser, stock fodder and ornamental vine. It now covers about 3 million hectares. Without natural insect or disease controls, the plant has proved prolific, climbing everything it comes in contact with.

Kudzu is respected in China and Japan, where it has been enjoyed as a common ingredient in foods and medications for centuries.

nzherald.co.nz/environment