Velvetleaf (Abutilon theophrasti) and green foxtail (Setaria viridis) response to corn (Zea mays) hybrid

A 2-yr study was conducted near Mead, NE, to determine the interaction of s ix corn (Zea mays) hybrids having different heights and leaf angles and fou r herbicide rates on velvetleaf(Abutilon theophrasti) and green foxtail (Se taria viridis) biomass rating and seed production. Corn hybrid grain yields averaged over herbicide rates differed by up to 1,100 kg/ha in 1993 and 3, 000 kg/ha in 1994, yet similar grain yield reductions occurred for all hybr ids as herbicide rate decreased. Corn hybrids differed in suppression of we ed growth and seed production, but suppression differences among hybrids we re not consistent across years. Plots with the very tall, erect-leaf hybrid had 7.4 velvetleaf plants/m(2), whereas other hybrids had 8.6 to 10.1 plan ts/m(2). Plots with the very tall, erect-leaf hybrid also produced the lowe st quantity of velvetleaf seeds of 23,100 seeds/m(2) versus 25,100 to 30,70 0 seeds/m(2) for plots with other hybrids. Erect-leaf hybrids suppressed we eds more effectively than horizontal-leaf hybrids. Corn hybrids had less ef fect on early- and late-season weed densities and biomass ratings and on se ed production than herbicide application. Selection among current corn hybr ids as a tool in integrated weed management will have a small or inconsiste nt influence on weed suppression.