New Zealand agriculture has become increasingly reliant on glyphosate for weed control, so avoiding or delaying glyphosate resistance is an important topic.

I recently attended an “Avoiding glyphosate resistance” workshop which was led by the Foundation of Arable Research (FAR).

The main guest speaker, Chris Preston of Adelaide University, shared his experience of working on weed resistance to glyphosate in Australia. Australia has a Glyphosate Sustainability Working Group that publishes useful information on the following website www.glyphosateresistance.org.au

New Zealand agriculture has become increasingly reliant on glyphosate for weed control, so avoiding or delaying glyphosate resistance is an important topic.

The discovery of glyphosate resistance has just been confirmed in a population of annual ryegrass on a vineyard in Marlborough so it is a timely topic too.

Here in New Zealand the greatest risk for encouraging glyphosate resistant weeds was identified as situations where glyphosate is applied alone and no other weed management is used.

Unlike cropping situations, pastoral-based production systems are not sprayed as frequently so they do not have as great a selection pressure as systems that are sprayed more frequently, or rely more on herbicide fallows.

However, every sector group at the workshop identified non-crop situations as having a relatively high risk of glyphosate-resistance, e.g., fencelines, tracks, yards and drains.

So what can you do now?

• Strategic use of alternate herbicides and modes of action; for example, when spraying out paddocks, use a suitable companion herbicide with glyphosate.
• When spraying non-crop areas, use suitable companion herbicides with glyphosate, including residual herbicides where possible.
• Ravensdown has a product mix that is ideal for spraying fencelines, tracks and around yards and buildings.
• Try and avoid situations where weed populations can build up to a high level.
• If weed escapes do occur, try and prevent them from setting seed. Consider non-chemical weed control options to assist weed control, such as cultivation, mowing, mulching or strategic grazing.
• Be aware of the risk of importing resistant or other problem weeds and them spreading around the farm.

George Kerse is Business Manager - Agrochemicals at Ravensdown

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