Measures to be taken against Didymo

Funding has been allocated to strengthen containment and to trial potential control and eradication methods for Didymosphenia geminata in Southland's Mararoa and lower Waiau rivers, Biosecurity Minister Jim Sutton said today.

New Zealand's efforts to investigate options for this invasive algae, known colloquially as "rocksnot", on a large scale is a world-first.

Mr Sutton said Cabinet approved $835,000 for environmental studies to identify, trial and assess the feasibility and effectiveness of potential control and eradication methods at selected sites in the river system.

Funding has also been allocated for a permitting scheme to strengthen containment of didymo while this research is being completed.

"Since didymo was first identified in these rivers in October 2004, Biosecurity New Zealand has focused on containment while long-term management options have been investigated."

Mr Sutton said public support of an awareness programme to prevent the spread has been fantastic, with up to 80 percent avoiding the rivers altogether.

"However, strengthening containment with a permit system will ensure that those 10-20 percent of people still using the river will be well informed and will have agreed to use the proper precautionary measures to prevent didymo from spreading to other areas."

Didymo can be killed on equipment used in the river system by completely drying items for at least 48 hours, or soaking and scrubbing in a mild (two percent) chlorine or mild (five percent) salt, nappy cleaner or detergent solution.

Mr Sutton said research conducted so far gave more confidence that we can contain didymo.

"It's crucial that didymo continues to be contained while BNZ investigates whether these cleaning methods can be used on a large scale to control or eradicate didymo within the river."

The outcomes from the control trials and other studies on impacts of the organism will help determine the long term management options for didymo. Biosecurity NZ is expected to report back to Cabinet early next year on available options and resource requirements.

The didymo incursion in Southland is the first documented example of the algae in the Southern Hemisphere. Didymo is an established invasive organism overseas and no attempts have previously been made to control or eradicate it.

More information on didymo is available on the Biosecurity NZ website: www.biosecurity.govt.nz/didymo

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