Agriculture, Aquaculture and Fisheries - Evaluation of Herbicide Products for Field Corn Production for Control of Suspected Triazine Resistant Lamb's

Abstract: Field corn production in New Brunswick has been increasing steadily, due to improved hybrid choice and favourable economic returns. The standard weed control program in field corn is based on the use of atrazine. Weed resistance to this family of herbicides has been found in many corn growing regions and is suspected to occur within New Brunswick. A trial was initiated near Keswick Ridge, New Brunswick to evaluate registered herbicides for weed control and crop tolerance in a field which had had previous lamb's–quarters escapes after atrazine applications. No significant crop injury was noted for any of treatments or evaluation timings. Weed control was reduced in the s–metolachlor/atrazine treatment due to lamb's–quarters escapes. All atrazine mixes that included additional herbicides with different modes of action had improved weed control. Other herbicides tested, including post–emergent treatments without atrazine components, were all effective in controlling the spectrum of weeds present in this field. Proper herbicide choice for producers will depend on product cost, weeds present in field and crop/weed stage. Growers should utilize proper herbicide rotations to ensure management of herbicide resistant weed populations.