Australia faces resistance in roadside weeds
Australian authorities and pesticide applicators are seeking ways to slow the development of resistance to the herbicide, glyphosate, in annual ryegrass ( Lolium rigidum) growing along roadsides. The first case of such resistance was detected in South Australia earlier this year and another suspected case is being investigated in New South Wales. The chairman of the Australian Glyphosate Sustainability Working Group, Dr Chris Preston, wants to see alternative control methods being used. “Most of the roadsides that we suspect have resistant ryegrass have seen intensive use of glyphosate over the past 15 years with at least one application each year,” he says.