title: Tolerance of two Bifora radians Bieb populations to ALS inhibitors in winter wheat.
abstract: BACKGROUND
  Bifora radians, an annual weed in winter wheat, is distributed mainly in the Mediterranean area, Asia Minor and the Caucasus. It infests winter-sown crops of the Central Anatolia and Middle Black Sea regions of Turkey. Field experiments in heavily B. radians-infested fields were conducted over 3 years in Samsun, Turkey, to determine the response of B. radians to ALS-inhibiting herbicides, because growers had complained of a decrease in herbicide effect.
  
  
  RESULTS
  The efficacy of ALS inhibitors on a putatively tolerant population sprayed annually with ALS inhibitors and an adjacent allegedly sensitive population was estimated at the ED(50) and ED(90) response levels. The recommended rates of herbicides controlled 90% of the weed (ED(90)) in the sensitive population at the early stage of B. radians development, but not in the tolerant population. The relative potencies (ED(x(tolerant))/ED(x(sensitive))) of herbicides on the two populations were estimated by assuming years as being random effects. The relative potency was on average about 1.7, irrespective of the ED(x) levels.
  
  
  CONCLUSIONS
  Although the relative potencies were not large, they were large enough to be noted by growers. In field experiments it would be important to establish tools demonstrating when farmers recognise loss of herbicide efficacy. There has been no indication of evolution of resistant biotypes so far, but continuous spraying favours biotypes with increased levels of tolerance.
authors: Department of Plant Protection, Agriculture Faculty, Ondokuz Mayıs University, Samsun, Turkey.
authors: Husrev
authors: H
authors: Mennan
authors: Jens C
authors: JC
authors: Streibig
authors: Mathieu
authors: M
authors: Ngouajio
authors: Emine
authors: E
authors: Kaya
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D053209:Herbicide Resistance; D006540:Herbicides / Q000494:pharmacology*; D010940:Plant Proteins / Q000037:antagonists & inhibitors*; D057685:Plant Weeds / Q000187:drug effects* / Q000201:enzymology; D012621:Seasons; D014908:Triticum / Q000254:growth & development; D014421:Turkey
chemical_list: D004791:Enzyme Inhibitors; D006540:Herbicides; D010940:Plant Proteins; D000095:Acetolactate Synthase