Caring for the environment  |  3 Jun 2020

Christchurch City Council is proposing a return to using more weed killers containing glyphosate.

The move could save the organisation about $3.5 million.

“In the last few years the Council has significantly reduced its use of weed killers containing glyphosate and instead used other weed control methods such as high-pressure steam, natural herbicides and hand-pulling,’’ says Council Head of Parks Andrew Rutledge.

“These methods though are more expensive and often less effective than using glyphosate-based weed killers. As part of the consultation on the revised Draft Annual Plan 2020-21 we want to find out what people think about us going back to using more glyphosate in our maintenance work.’’

At the moment the Council’s Parks teams and contractors only uses weed killers containing glyphosate to control pest plants where no other method is practical.

Mr Rutledge says the Council’s initial move in 2016 to reduce the use of weed killers with glyphosate in them followed a 2015 announcement from the International Agency for Cancer Research that they had identified glyphosate as a likely carcinogen for humans.

“Although New Zealand’s Environmental Protection Authority (EPA) has always approved glyphosate for use here, we proposed a change in approach for the Annual Plan 2016–17 which the Council at the time adopted,” Mr Rutledge says.

The EPA commissioned a 2016 report which confirmed their position that it was unlikely glyphosate poses a risk and that it should not be classified either as a carcinogen or mutagen under the Hazardous Substances and New Organisms Act.

“We’ve made great progress with these organic measures in our parks, but they’re more labour intensive and about five times more expensive, so this proposed change would be a quick and easy way to save a lot of money in the current economic environment,” Mr Rutledge says.

Council Transport Operations Manager Steffan Thomas says the alternative organic measures have some other issues when it comes to controlling weeds on our roads.

“Alternative organic fatty acid herbicides can’t be used near drains or waterways because they’re toxic to aquatic life,” Mr Thomas says.

“Non-chemical technology like high pressure steam takes longer to apply, and can require more applications before it’s successful at controlling weeds on our roads. The additional costs of labour and associated traffic management make this approach more expensive, and it also means workers are out in the road environment for longer, exposing them to the hazards associated with traffic.”

Consultation on the revised Draft Annual Plan 2020/21 opens on 12 June.