Council to consult on willow control
6 July 2006
The Waitakere City Council is to begin consultation with Bethell’s landowners about new plans to eradicate invasive
willow trees from the Te Henga wetland.
Willows are a major threat to the wetland’s unique habitat because they block streams, greatly increasing the risk of
major flooding, and crowd-out native vegetation.
In addition to having many distinctive wetland plants, the Te Henga’s wetland is also home to many freshwater birds
including the endangered Australasian Bittern, the North Island Fernbird as well as Banded Rail and Marsh Crake.
The council aims to start consulting with affected landowners this month on eradicating the willows using targeted
aerial spraying - using a herbicide which is permitted for use near water.
Extensive tests have shown that the herbicide, Roundup G2, breaks down to natural compounds upon contact with water and
does not affect fish, invertebrates or birds.
If landowner approval is given, the council aims to conduct a trial spray on willows in a small area first and present
the results to landowners.
Targeted aerial spot spraying is the council’s preferred method of eradication as the current practice (hand-drilling
and injecting individual trees with herbicide) is proving too slow to stop the willows spreading.
Aerial spraying is suitable for dense areas of willows with large leafy canopies.
In areas where there are willows in amongst native flora, the aerial spraying will target individual trees - but only
those with large enough canopies and those without native vegetation in their canopies.
Willows not meeting those criteria will continue to be individually drilled and injected.
Mobile weather stations and differential GPS systems will be used in any spraying operation to ensure spray drift is
absolutely minimised.
If Bethell’s/Te Henga wetland landowners consent to the operation the next step will be to digitally map the willows in
September this year.
ENDS