12 Nov 2010

Kiwifruit disease raises vine management issue

2:03 pm on 12 November 2010

The appearance of the kiwifruit vine disease PSA has raised the issue of vine management.

The bacterial infection has been confirmed on three Te Puke orchards. Six other orchards are now in quarantine and more than 100 properties report having symptoms of the disease.

Zespri chief executive Lain Jager says because the industry doesn't yet know how the bacteria got here or how long ago, growers are discussing whether or not they'll need to make changes in vine management to reduce the stress on the plants.

That includes the practice of girdling, or ring barking the tree, which stresses the plant and drives up dry matter levels - a way of managing the vine to produce high-sugar fruit.

He says vine management systems could have played a part, or symptoms might have appeared because too much water was through the vines in winter.

Mr Jager says the kiwifruit industry will also be checking the archive or library it keeps of old plant material to see if it throws up any clues as to how long the disease has been here.

Meanwhile, Northland Fruitgrowers Federation representative, Rick Curtis, says there's been no sign of the disease in the north so far. Growers hope the region's distance from Bay of Plenty protect their vines.

Mr Curtis says a strict hygiene regime is now in place for workers, vehicles, and equipment moving between orchards; and field days have been cancelled to minimise the risk of any spread.

Nelson kiwifruit growers, who met on Friday morning, are also stepping up measures to protect their vines from the PSA disease.