Effect of EPSPS gene copy number and glyphosate selection on fitness of glyphosate-resistant Bassia scoparia in the field

Abstract The widespread evolution of glyphosate-resistant (GR) Bassia scoparia in the U.S. Great Plains poses a serious threat to long-term sustainability GR sugar beet. Glyphosate resistance B. is due an increase EPSPS (5-enolpyruvyl-shikimate-3-phosphate) gene copy number. variation copies among individuals from within single population indicated differential response glyphosate selection. With continued use beet, effect increasing rates (applied as or sequential applications) on fitness with variable was tested under field conditions. number and total rate (single did not influence any reproductive traits , except seed production. Sequential applications 2214 g ae ha −1 higher prevented production scopari plants 2–4 (low levels resistance) 5–6 (moderate copies. Timely (full recommended rates) can potentially slow down low moderate (2–6 copies), but survivors (highly-resistant ≥ 8 copies) need be mechanically removed before flowering beet fields. This research warrants adopt ecologically based, multi-tactic strategies reduce exposure