Australia
June 17, 2013

AHRIinsight #8

Most of us are a bit slow out of bed on a cold morning and take a little while to get moving. Weeds are no different. Some glyphosate resistant weeds become less resistant in cool weather.

One of the mechanisms of resistance to glyphosate is to reduce the movement of the chemical through the plant (known as translocation). Researcher Dr Martin Vila-Aiub and others from AHRI tested annual ryegrass and Johnsongrass with this resistance mechanism. They found that the plants were much less resistant to glyphosate when the plants were grown in cool conditions.

The good news? If you know that the resistant weeds you are spraying have the reduced translocation mechanism, then spraying in cool weather may help.

The bad news? There are multiple mechanisms of glyphosate resistance so it is difficult to know which one you are dealing with.

However, it may be possible to improve the control of glyphosate resistant weeds by spraying glyphosate in the cooler months of the year and avoiding glyphosate in the warmer months. Similarly, this approach may reduce the evolution of glyphosate resistance.

For more information, including details about the temperature at which the weeds were sprayed, click here.

Website: http://www.ahri.uwa.edu.au/

Published: June 17, 2013