Promising Start To Lake Karapiro Weed Control

An aquatic weed management programme aimed at controlling the invasive weed hornwort in Lake Karapiro has produced excellent results so far, Land Information New Zealand (LINZ) said today.

Fifty hectares of Lake Karapiro was targeted when the programme began in May with an aerial application of herbicide. Hornwort forms dense mats that affect the lake’s rowing course and swimming, boating and fishing activities.

“Hornwort has been effectively controlled in the areas we targeted, including places where the weed had spread right across the lake” said Paul Jackson, LINZ’s Crown Property Manager.

“This is an excellent first result. It’s not possible to eradicate hornwort because it regrows very easily, but we’ve shown we can achieve a good measure of control. This is good news for recreational users and the community as it works towards hosting the World Rowing Championships in 2010.”

Mr Jackson said helping to ensure the rowing course is up to international standards when the championships are held is one of the aims of the management programme, but all lake users will gain from weed control planned for the next few years.

Feedback from recreational users and community representatives about the work to date had been very positive, he said.

Monitoring by the National Institute of Water and Atmospheric Research found that the herbicide treatment had no adverse effects on water quality or fish populations, including eels, Mr Jackson said.

“The resource consent granted by Environment Waikato set strict conditions for this work which have been met.”

A second control operation is due to start on 10 September when a further 50 hectares of weed will be treated. One to two days are required to complete the work which will involve an aerial application of Diquat, a plant herbicide safely used in New Zealand lakes for more than 40 years.

If weather and water conditions are poor on 10 September, the work will take place on the next suitable day, excluding weekends or public holidays.

ENDS

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