Velvetleaf (Abutilon theophrasti) and Green Foxtail (Setaria viridis) Response to Corn (Zea mays) Hybrid1

Abstract

A 2-yr study was conducted near Mead, NE, to determine the interaction of six corn (Zea mays) hybrids having different heights and leaf angles and four herbicide rates on velvetleaf (Abutilon theophrasti) and green foxtail (Setaria 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 hybrids as herbicide rate decreased. Corn hybrids differed in suppression of weed growth and seed production, but suppression differences among hybrids were not consistent across years. Plots with the very tall, erect-leaf hybrid had 7.4 velvetleaf plants/m2, whereas other hybrids had 8.6 to 10.1 plants/m2. Plots with the very tall, erect-leaf hybrid also produced the lowest quantity of velvetleaf seeds of 23,100 seeds/m2 versus 25,100 to 30,700 seeds/m2 for plots with other hybrids. Erect-leaf hybrids suppressed weeds more effectively than horizontal-leaf hybrids. Corn hybrids had less effect on early- Fand late-season weed densities and biomass ratings and on seed production than herbicide application. Selection among current corn hybrids as a tool in integrated weed management will have a small or inconsistent influence on weed suppression.Nomenclature: Alachlor, 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide; atrazine, 6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine; green foxtail, Setaria viridis #3 SETVI; velvetleaf, Abutilon theophrasti Medik. # ABUTH; corn, Zea mays L.Additional index words: Grain yield, herbicide, integrated weed control, reduced input, weed seed production, weed competition, ABUTH, SETVI.Abbreviations: GDD, growing degree days; IFS, Illinois Foundation Seed.