Johnsongrass, a tall, coarse, perennial grass, is the second most common and troublesome weed in field corn in Texas. Field experiments were conducted in 1996 to 1998 to evaluate an integrated johnsongrass management program in bedded and irrigated field corn. Nicosulfuron at 26.3 g ai/ha applied banded over the row to 50% of the planted area plus one cultivation resulted in johnsongrass control of aboveground and rhizome biomass and in corn yield comparable to the labeled rate (35 g ai/ha) when applied two consecutive years in the same plots. This treatment reduced cost 27% and reduced herbicide input 62% compared to nicosulfuron applied broadcast at labeled rate without cultivation. Economic benefits of this johnsongrass management program are promising for field corn producers.

Quackgrass is a serious weed problem in the northern United States and southern Canada. Field experiments were conducted in 1990 and 1991 to examine the effect of herbicide rate, application timing, quackgrass growth stage, and cultivation on quackgrass control with nicosulfuron and primisulfuron in corn. Nicosulfuron (35 g ai/ha) and primisulfuron (40 g ai/ha) each provided 84% or greater control of two-leaf plants and 93% or greater control of four-leaf quackgrass plants. Sequential applications of both nicosulfuron and primisulfuron provided greater season-long control than single applications of the same rate on two-leaf but not four-leaf quackgrass. Cultivation 10 d after nicosulfuron or primisulfuron application often increased early-season control, but by corn harvest few differences were observed. Postemergence (POST) applications of nicosulfuron and primisulfuron provided at least 88% control, compared with 66 to 86% from an early preplant application of glyphosate. Corn yields were similar regardless of the quackgrass control program.