Explainer: Review of weed management in the road corridor

Last Updated : 11 Nov 2020
Explainer: Review of weed management in the road corridor

Auckland Council is reviewing how it manages weeds on roads, footpaths, and berms across the city, otherwise known as the urban road corridor.

Currently, regional budgets are used to fund weed management in the road corridor, but some areas get more expensive methodologies such as thermal technology (e.g. hot water), while others get the cheaper methodology of glyphosate. In effect, this means that the areas receiving the cheaper methods are unfairly subsidizing the areas that get the more expensive weed control.

This week the council’s Environment and Climate Change Committee will consider endorsing a recommendation for a standard mixed method approach across the region. The recommended approach will reduce current levels of glyphosate, water use and carbon emissions regionwide.

Here are the top need-to-know facts about the council’s review and its recommendation.

Auckland’s approach to weed management in the road corridor needs updating

The current approach to weed management in the road corridor is no longer fit for purpose. Although funded by regional budgets, each local area still uses the same methods that were put in place by legacy councils and this has created inequity. For example, the North Shore predominantly use thermal methods while Manukau and Waitākere mainly use glyphosate. This means ratepayers in some areas of Auckland effectively subsidise the more expensive thermal methods used in other areas.

The recommended approach is fairer and provides for local choice

Under this proposal regional budgets will be distributed fairly across all local boards by funding the recommended method of combined plant-based herbicide and glyphosate.

However, this does not mean that local boards must use this approach. Local board areas may choose a different approach if they are willing to fund the cost difference from their local budget or a local targeted rate.

If a standardised regional approach is agreed there will still be no changes to operations until local boards have made their decisions and local funding is available.

The recommended approach will reduce glyphosate, carbon emissions and water use across the region

Auckland Council wants to have one standard approach to weed management - a mixed method using plant-based herbicides with spot-sprayed glyphosate on hard to manage weeds.  This would reduce the amount of glyphosate, water, and carbon emissions we currently use. This approach is estimated to be achievable within existing budgets.

Thermal methods use more water, emit more carbon and cost more than a mixed method approach

Using hot water to kill weeds requires 10 to 12 litres of water per minute and generates high carbon emissions because diesel boilers are needed to heat the water. Generally, more treatments are needed each year because the water doesn’t kill the weeds at their roots. More staff are needed to meet the operational requirements of this approach. In areas where thermal is used spot spraying with glyphosate is also required because not all weeds are effectively managed by the treatment. For these reasons, thermal methods are not recommended as part of a standard approach for now.

However, the council and its contractors will continue to evaluate best practice methods. If new technology becomes available that enables less water use, herbicides and greenhouse gas emissions for weed management at a similar price, then we will work with contractors to explore options to adapt our services. 

Anyone can opt-out of having weeds sprayed near their property

You don’t have to have any herbicides sprayed outside your property if you don’t want to.

Auckland Council has a no-spray register, which anyone can join to opt-out of weed control with agrichemicals on the berm or park boundary of your property. If you join this register, the street frontage outside your property will not be sprayed with herbicide as long as you adequately maintain the area yourself.

Want to know more about this review?

Read this Our Auckland story for more background information and access the report prepared for the Environment and Climate Change Committee here.

More information about the regulation of glyphosate in New Zealand and a summary of the very latest international research can be found on the EPA website here.

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