title: Benchmark study on glyphosate-resistant cropping systems in the United States. Part 5: Effects of glyphosate-based weed management programs on farm-level profitability.
abstract: BACKGROUND
  Glyphosate-resistant (GR) crops have changed the way growers manage weeds and implement control strategies. Since the introduction of GR crops, growers in many instances have relied on glyphosate almost exclusively to control a broad spectrum of weeds. This over-reliance on glyphosate has resulted in the evolution of glyphosate resistance in some weed species. Growers and scientists are concerned about the sustainability of GR crops and glyphosate. When a grower is making decisions about weed control strategies, economic costs and benefits of the program are primary criteria for selection and implementation. Studies across six states were initiated in 2006 to compare the economics of using a weed resistance best management practice (BMP) system with a grower's standard production system.
  
  
  RESULTS
  Resistance BMP systems recommended by university scientists were more costly but provided similar yields and economic returns. Rotation of GR crops resulted in a higher net return (maize and soybean) compared with continuous GR crop (cotton or soybean) or rotating a GR crop with a non-GR crop (maize).
  
  
  CONCLUSIONS
  Growers can implement weed resistance BMP systems with the confidence that their net returns will be equivalent in the short run, and, in the long term, resistance BMP systems will prevent or delay the evolution of GR weeds in their fields, resulting in substantial savings.
authors.affiliation: Plant and Soil Sciences Department, Mississippi State University, Mississippi State, MS 39762, USA. weirichj@missouri.edu
authors.forename: Jason W
authors.initials: JW
authors.lastname: Weirich
authors.forename: David R
authors.initials: DR
authors.lastname: Shaw
authors.forename: Micheal D K
authors.initials: MD
authors.lastname: Owen
authors.forename: Philip M
authors.initials: PM
authors.lastname: Dixon
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Weller
authors.forename: Bryan G
authors.initials: BG
authors.lastname: Young
authors.forename: Robert G
authors.initials: RG
authors.lastname: Wilson
authors.forename: David L
authors.initials: DL
authors.lastname: Jordan
mesh_terms: D000383:Agriculture / Q000191:economics* / Q000379:methods; D019985:Benchmarking; D018556:Crops, Agricultural / Q000187:drug effects / Q000191:economics* / Q000235:genetics / Q000254:growth & development; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D014481:United States; D058728:Weed Control / Q000191:economics* / Q000379:methods; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D000097797:Glyphosate