Will using the double knock lower the risk of glyphosate resistant ryegrass?
Yes, but only when used correctly. The double knock of glyphosate followed by application of a paraquat-based product relies on both herbicides being applied at rates appropriate for the ryegrass plants being targeted. The strategy relies on control of the rare glyphosate resistant survivors by the paraquat. The glyphosate survivors are not likely to be controlled by low rates of paraquat. Similarly, large ryegrass plants are unlikely to be controlled by paraquat.
