title: A risk calculator for glyphosate resistance in Lolium rigidum (Gaud.).
abstract: BACKGROUND
  Glyphosate resistance has been confirmed in 58 populations of Lolium rigidum (Gaud.), a major weed of crops in southern Australia. Extensive use of glyphosate in conjunction with minimal soil disturbance has been identified as high risk for resistance to that herbicide. Land managers need a simple method for rapid assessment of the risk of resistance occurring as a result of past and proposed future management practices. Modelled on risk assessment nomographs, a simple calculator for indicating the risk of evolved glyphosate resistance in L. rigidum is described.
  
  
  RESULTS
  The calculator uses the generations since first use and the frequency of use of glyphosate in combination with historical cultivation levels as critical factors for determining the risk of glyphosate resistance evolution. Based on the management history of a field, a land manager can graphically determine a glyphosate resistance risk for that field.
  
  
  CONCLUSIONS
  The calculator enables the farmer or the advisor to assess the risk of a weed's population becoming resistant and modify practices accordingly to manage for sustainable glyphosate use. The risk calculator could be modified for other herbicides and different weed species.
authors: EH Graham Centre, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia. Rex.Stanton@dpi.nsw.gov.au
authors: Rex A
authors: RA
authors: Stanton
authors: James E
authors: JE
authors: Pratley
authors: David
authors: D
authors: Hudson
authors: Gerald M
authors: GM
authors: Dill
mesh_terms: D005998:Glycine / Q000031:analogs & derivatives*; D053209:Herbicide Resistance / Q000235:genetics; D006540:Herbicides; D008129:Lolium / Q000235:genetics*; D049451:Nomograms; D018570:Risk Assessment / Q000379:methods; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D000097797:Glyphosate