title: Identification of glyphosate resistance in Salsola tragus in north-eastern Oregon.
abstract: BACKGROUND
  Farmers in the low-rainfall region of eastern Oregon rely on repeated applications of non-selective herbicides, predominately glyphosate, to control Salsola tragus in no-till fallow systems. Reports of poor glyphosate effectiveness have increased in recent years. Reduced efficacy is often attributed to dust, water stress, or generally poor growing conditions during application. Inadequate control also may be the result of the evolution of glyphosate resistance. Therefore, studies were undertaken to determine if glyphosate-resistant S. tragus populations occur in Oregon.
  
  
  RESULTS
  Results from dose-response studies confirmed glyphosate resistance in three of 10 Oregon Salsola tragus populations. The ratio I50R/I50Sfrom dose-response curves was, on average, 3.1 for the relative dry biomass per plant and 3.2 for the % of surviving plants per pot in these three populations. Plant mortality at recommended glyphosate doses for the resistant populations was less than 30% 3 weeks after treatment.
  
  
  CONCLUSIONS
  Glyphosate resistance in S. tragus highlights the imperative need to diversify weed control strategies to preserve the longevity and sustainability of herbicides in semi-arid cropping systems of the Pacific Northwest. © 2017 Society of Chemical Industry.
authors.affiliation: Columbia Basin Agricultural Research Center (CBARC), Department of Crop and Soil Science, Oregon State University, Pendleton, OR, USA.
authors.forename: Judit
authors.initials: J
authors.lastname: Barroso
authors.affiliation: Columbia Basin Agricultural Research Center (CBARC), Department of Crop and Soil Science, Oregon State University, Pendleton, OR, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Gourlie
authors.affiliation: Morrow County Extension Office, Department of Crop and Soil Science, Oregon State University, Heppner, OR, USA.
authors.forename: Larry K
authors.initials: LK
authors.lastname: Lutcher
authors.affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, OR, USA.
authors.forename: Mingyang
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Crop and Soil Science, Oregon State University, Corvallis, OR, USA.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Mallory-Smith
mesh_terms: D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D009922:Oregon; D031248:Salsola / Q000187:drug effects* / Q000502:physiology; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D000097797:Glyphosate
keywords: Russian thistle; Salsola kali; glyphosate-resistant; tumbleweed