title: Response of imidazolinone-tolerant and -susceptible volunteer oilseed rape (Brassica napus L.) to ALS inhibitors and alternative herbicides.
abstract: BACKGROUND
  Imidazolinone-tolerant oilseed rape (Brassica napus L.) varieties are currently grown in Canada, North America, Chile and Australia with high acreage. A Europe-wide introduction has started and will be pushed further for both spring and winter varieties. The primary aim of this study was to evaluate the impact of imidazolinone tolerance for future volunteer oilseed rape control in subsequent crops, particularly winter wheat.
  
  
  RESULTS
  A greenhouse bioassay showed cross-tolerance of imidazolinone-tolerant oilseed rape towards sulfonylureas, triazolopyrimidines and sulfonylaminocarbonyltriazolinones (resistance factors between 5 and 775), with a homozygous variety expressing a much higher tolerance level compared with a heterozygous variety. Calculated ED90 values suitable for controlling tolerant plants were always much higher than the recommended herbicide dose. Generally, results were confirmed under field conditions, but with higher efficacies than expected in some cases (e.g. florasulam). Herbicides with an alternative mode of action were found to be effective in controlling imidazolinone-tolerant volunteers in subsequent winter wheat crops.
  
  
  CONCLUSIONS
  Herbicide strategies have to be adjusted for volunteer control in subsequent crops if imidazolinone-tolerant oilseed rape varieties are to be grown. However, agronomic tools (harvest date, harvest technique, tillage) should be used conscientiously in the first place to keep volunteer oilseed rape densities at the lowest possible level.
authors.affiliation: Department of Life Sciences and Engineering, University of Applied Sciences Bingen, Bingen, Germany. christophkrato@web.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Krato
authors.forename: Karin
authors.initials: K
authors.lastname: Hartung
authors.forename: Jan
authors.initials: J
authors.lastname: Petersen
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors*; D029688:Brassica napus / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006540:Herbicides / Q000494:pharmacology*; D010940:Plant Proteins / Q000037:antagonists & inhibitors*
chemical_list: D004791:Enzyme Inhibitors; D006540:Herbicides; D010940:Plant Proteins; D000095:Acetolactate Synthase