Foxtail (Setaria spp.) seedling dynamics in spring wheat (Triticum aestivum) are influenced by seeding date and tillage regime

Emergence patterns of foxtail in spring wheat following soybean were evalua ted for three seeding dates and three tillage regimes. Cumulative foxtail e mergence, as a percentage of total plants emerged in the growing season, wa s generally not influenced by tillage regime throughout most of the emergen ce period, but when differences occurred, emergence was lower with no-till than with moldboard plow Foxtail seedling densities were greater in no-till and chisel plow than in moldboard plow Weed biomass and wheat yields were not: affected by tillage regime. Delaying wheat seeding reduced foxtail per cent emergence and emerged seedling density. Differences in emergence patte rns of foxtail were attributable to thermal accumulation after seeding. Whe at yield was not influenced by seeding date in 2 of 3 yr.