Initial weed densities affect no-tillage weed management with a rye (Secale cereale) cover crop

The objective of this research was to evaluate the influence of different initial weed densities on weed control effectiveness in no-tillage corn at two locations in North Carolina during 1994 and 1995. Different weed densities were established over a 4-year period (1989-1992) by using various weed management strategies. Resultant density levels were estimated and used to establish high and low weed density plots. Treatments applied were PRE, POST, at-planting, and an untreated control. Weed density estimates were made 37 and 57 DAP Common lambsquarters at low densities (20 to 40 weeds/m(2)) was controlled with the cover crop alone, but common lambsquarters at high densities (150 to 170 weeds/m(2)) and redroot pigweed at any density were not controlled. POST herbicides reduced weed densities as well as the PRE herbicides, regardless of initial weed densities.