Long-spine sandbur [Cenchrus longispinus (Hack. in Kneuck.) Fernald] control in corn

Abstract

Long-spine sandbur is an annual grass that infests many fields in southwestern Ontario, especially those with sandy soils. Eight field experiments were conducted over a 2-yr period (2007, 2008) in Ontario to determine the efficacy of various preemergence (PRE) and postemergence (POST) herbicides for control of long-spine sandbur in corn. Generally, the POST applied herbicides controlled long-spine sandbur better than PRE herbicides evaluated in this study. PRE application of dimethenamid-p (1250 g a.i. ha-1), S-metolachlor (1600 g a.i. ha-1), flufenacet (1040 g a.i. ha-1), pendimethalin (1680 g a.i. ha-1), pyroxasulfone (250 g a.i. ha-1), or isoxaflutole plus atrazine (105 + 1063 g a.i. ha-1) controlled long-spine sandbur 0-79%. POST application mesotrione + atrazine (140 + 280 g a.i. ha-1) or topramezone + atrazine (18.75 + 500 g a.i. ha-1) provided 24-82% control, foramsulfuron (35 g a.i. ha-1) or primisulfuron/dicamba (26 +140 g a.i. ha-1) provided 54-87% control, and rimsulfuron (15 g a.i. ha-1), nicosulfuron (25 g a.i. ha-1) or nicosulfuron/rimsulfuron (25 g a.i. ha-1) provided 68-95% control of long-spine sandbur in corn. Similar reduction in sandbur density and shoot dry weight were observed. PRE applied isoxaflutole + atrazine and POST applied rimsulfuron, nicosulfuron, nicosulfuron/rimsulfuron, foramsulfuron, primisulfuron/dicamba, and topramezone + atrazine all provided yield comparable with the weed-free control. Among the herbicides evaluated rimsulfuron, nicosulfuron, and nicosulfuron/rimsulfuron provide the most consistent long-spine sandbur control in corn.Key words: Weed control, preemergence herbicide, postemergence herbicide, rimsulfuron, nicosulfuron, foramsulfuron, primisulfuron, dicamba, topramezone, atrazine