Herbicide Combinations for Soybean (Glycine max) Planted in Stale Seedbed

Abstract

Barnyardgrass 7 to 25 cm tall was controlled 48 to 74% with paraquat (420 g/ha), 83 to 87% with glyphosate (1120 g/ha), and 85 to 91% with glufosinate (840 g/ha). In most cases barnyardgrass control was not enhanced with addition of residual herbicides metribuzin plus chlorimuron, metribuzin, or imazaquin. Barnyardgrass and seedling johnsongrass no more than 13 cm tall was controlled at least 90% regardless of herbicide treatment. When rhizome and seedling johnsongrass were present, control with glyphosate was 96% compared with 55% for paraquat and 86% with glufosinate. Tank-mixtures of non-selective and residual herbicides generally enhanced control of entireleaf and pitted morningglory, hemp sesbania (15 to 30 cm), and prickly sida (15 to 18 cm). Soybean yields in most cases were not increased with addition of residual herbicides. Yield following glufosinate applied alone was 25% higher than following paraquat, and for all herbicide treatments yields were at least 45% greater than when a non-selective herbicide was not applied.