Response of Purple Nutsedge to Repeated Applications of Glyphosate

Purple nutsedge ( Cyperus rotundus L.) plants were treated in the greenhouse and field with glyphosate [ N -(phosphonomethyl)glycine]. Fresh weight of leaves, sprouts per original tuber, and sprouts per new tuber were reduced by 4 kg/ha glyphosate in the greenhouse. In the field, glyphosate at 2 and 4 kg/ha was compared to several herbicides for nutsedge control in repeated applications over an 8-month period. After several applications, glyphosate reduced the number of plants per unit area. After rotovation (working the soil thoroughly to a depth of 15 cm) and reapplication, glyphosate and MSMA (monosodium methanearsonate) plots had fewer plants and tubers per unit area than controls.