Managing weed resistance to glyphosate

Dr Charlie Reinhardt of the University of Pretoria’s SA Herbicide Resistance Initiative offers the following ‘5 Golden Rules’ for managing weed resistance to glyphosate and other herbicides.

• Reduce weed populations on lands;
• Do not allow weeds to set seed before they are killed off;
• Utilise the relevant traits of various crops to ‘outcompete’ weeds;
• Rotate herbicides with different mechanisms of action. This will require farmers to also rotate crops according to the herbicides used;
• Determine whether weed resistance to glyphosate and other herbicides is real or apparent, and then use the best management strategy to kill them.

“Where possible, before crop seed is planted, use a mixture of glyphosate and 2,4-D to give difficult weeds a double knock,” adds Reinhardt. “Herbicides with residual effects in the soil can be valuable tools for controlling these weeds, and those emerging in flushes throughout the growing season.”