Population Dynamics and Control of Annual Weeds in Corn (Zea mays) as Influenced by Tillage Systems

Field research was conducted at Hancock, WI, from 1985 through 1987 to evaluate effects of conventional tillage, chisel plow, ridge tillage, and no-tillage systems on population dynamics and control of annual weed species in corn grown continuously on a loamy sand soil without irrigation. In all years of the study, green foxtail densities were greater in chisel plow and no-tillage than in the conventional tillage system, while ridge tillage had densities lower than all other tillage systems. Common lambsquarters density in the chisel plow system reached nearly 500 plants m −2 compared to less than 75 plants m −2 in the other tillage systems when averaged over years. Average redroot pigweed densities in the no-tillage and chisel plow systems were 307 and 245 plants m −2 compared to less than 25 plants m −2 in the conventional and ridge tillage systems. Horseweed was observed only in no-tillage and ridge tillage plots. Green foxtail and redroot pigweed were more difficult to control in chisel plow and no-tillage than in the conventional and ridge tillage systems with several herbicide treatments. Corn yields were not affected by tillage systems under weed-free conditions. Corn yield differences among tillage systems when the same herbicide treatment was applied appeared to be due to differences in weed control.