Activity of Acetanilide Herbicides on Yellow Nutsedge (Cyperus esculentus)

Abstract

The acetanilide herbicides alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide], the ethyl ester of diethatyl [N-(chloroacetyl)-N-(2,6-diethylphenyl)glycine], or H-26910, the isopropyl ester ofN-(chloroacetyl)-N-(2-methyl-6-ethylphenyl)glycine, failed to inhibit yellow nutsedge (Cyperus esculentusL. ♯ CYPES) tuber sprouting in petri dishes. At 3.5 and 0.35 μM, all herbicides inhibited growth of newly emerging shoots. There was no significant difference in activity among alachlor, metolachlor, diethatyl ethyl, and R-26910 on yellow nutsedge sprouts grown in petri dishes. In soil, metolachlor and alachlor were equally effective for yellow nutsedge control. Both were more effective than H-26910 at high levels of soil organic matter. Diethatyl ethyl was least effective at all levels of soil organic matter. For all herbicides evaluated, activity decreased with increased levels of organic matter in the soil. For acetanilide herbicides to be effective on yellow nutsedge, they needed to be in the soil zone, above or at the level of the tuber.