Common management alternatives were compared in a factorial arrangement for 2 yr to determine their effects on green foxtail and yellow foxtail seed production in spring wheat in the Northern Great Plains of the United States. Seed production was measured twice, at wheat harvest (in August) and postharvest (after first lethal frost in autumn). Management alternatives were early, middle, and late crop-sowing dates; no-till, chisel, and moldboard plow tillage systems; and broadleaf herbicide only and broadleaf herbicide plus fenoxaprop applications. Fenoxaprop reduced foxtail seed production at wheat harvest but not at postharvest. Early sowing also decreased seed production at wheat harvest but increased postharvest seed production. Tillage system had no consistent effects on foxtail seed production. Postharvest seed production often was greater than or equal to that at wheat harvest regardless of management system. These results indicate that in-crop management alternatives, such as postemergence grass herbicide and early crop sowing, may lower the number of foxtail seeds at harvest substantially, but they must be accompanied by postharvest weed control to reduce overall seed production.
Nomenclature: Fenoxaprop; green foxtail, Setaria viridis (L.) Beauv. #3 SETVI; yellow foxtail, Setaria pumila (Poir.) Roem. & Schult. [=Setaria glauca (L.) Beauv.] # SETLU; spring wheat, Triticum aestivum L. ‘Sharpe’.
Additional index words: Sowing date, tillage regime.
Abbreviations: CP, chisel plow; GDD, growing degree-days; MP, moldboard plow; NT, no-till.