Wool joins weed fight

An innovative and sustainable method is being trialled in Taitokerau to supress Egeria densa, an invasive oxygen weed found in Rotokawau on the Poutō Peninsula.

The Northland Regional Council’s biodiversity, biosecurity marine and maritime teams collaborated towards the end of last year to lay wool matting on 412m square metres of the lake floor with support from local commercial divers.

The New Zealand grown wool, which resembles a carpet underlay, offers a non-toxic and cost-effective solution.

NRC biodiversity manager Lisa Forester says until now, the lake was hand-weeded by divers – a painstakingly slow, labour-intensive and costly process.

“Using a natural fibre will allow native plants to easily recolonise while acting as a weed suppressant, preventing the oxygen weed from pushing through and, hopefully, eradicating the pest plant over time.”

Kaipara constituency councillor John Blackwell says at Rotokawau is one of 12 lakes ranked as ‘outstanding’ in Te Taitokerau.

“If we don’t act now, the oxygen weed will eventually fill the lake, smothering native plants in the process and degrading the water quality,” he says.

The biodiversity team will revisit the lake in late summer to check on the wool matting and continue weed checks twice a year.

NRC has reiterated the importance of using the ‘Check, Clean and Dry’ method when visiting any Te Taitokerau lakes or waterways.

“Always check your gear, clean and then fully dry it before moving between waterways. This is especially important now that the invasive freshwater clam has arrived in New Zealand.”