Annual ryegrass with herbicide resistance is now common in southern NSW, according to collaborative research between Charles Sturt University (CSU) and the NSW Department of Primary Industries (DPI) recently completed at the EH Graham Centre for Agricultural Innovation. In studies conducted from Dubbo in the state’s central west, to the Victorian border in the south, and east-west between the Hume and Newell highways, researchers Mr John Broster and Mr Eric Koetz have found high levels of resistance in ryegrass to widely used herbicides. Director of the EH Graham Centre, Professor Deirdre Lemerle, said these findings show a large increase since the last thorough survey was conducted in 1991. “Around 80 per cent of paddocks surveyed in 2007 had significant levels of resistance to Group A ‘fops’ herbicides, while resistance to Group B ‘SU’ herbicides are in 65 to 70 per cent of paddocks.” Professor Lemerle said 17 years ago, only 10 to 15 per cent of paddocks had ryegrass with resistance to these herbicides. “These high levels of resistance reinforce the importance of developing and introducing new non-chemical weed control techniques into our weed management strategies,” she said. The research is part of a larger survey across the wheat-belt, funded by the Grains Research and Development Corporation.