Recent surveys of Tasmanian ryegrass (Lolium spp.) populations have shown a significant increase in Group A herbicide resistance. John Broster (Charles Sturt University) found an increase in resistance from 18% in 2010 to 46% in 2015 to diclofop-methyl ‘Fop’ and sethoxydim ‘Dim’ herbicides.

The selection of resistant weeds can occur in just 3-4 years if herbicide groups (Modes of Action) are not rotated. Read this fact sheet for an overview of herbicide resistance and what you can do to avoid and minimise the risk of resistance developing.