Managing glyphosate resistant weeds in Australia.

Glyphosate resistance has evolved in three grass weed species in Australia. By far the greatest problem is with Lolium rigidum Gaudin, but more recently resistant populations of Echinochloa colona (L.) Link and Urochloa panicoides P.Beauv. have been reported. Glyphosate resistance occurs in a wide range of situations including grain cropping, chemical fallows, in orchards, vineyards, along irrigation channels, along fence lines, railway rights of way and roadsides. Glyphosate resistance occurs where glyphosate has been intensively used, either once or many times per year, where no other effective herbicides are applied and where no other effective weed management is conducted. The rate and annual intensity of glyphosate use is not well correlated with the appearance of glyphosate resistance. Instead, the lack of other weed management practices is a better predictor of resistance. The Australian Glyphosate Sustainability Working Group (AGSWG) is a cross-industry group with the aim of identifying and disseminating key information and strategies for the management of glyphosate resistant weeds to all sectors in Australia. It provides information on confirmed cases of resistance, answers to glyphosate resistance issues and strategies for management of glyphosate resistance. By providing clear and consistent messages about glyphosate resistance across industry sectors it is hoped to reduce the incidence and impact of glyphosate-resistant weeds.