Tolerance of Imidazolinone-Resistant Corn (Zea mays) to Diclosulam1
2003
BAILEY, WILLIAM A. | WILCUT, JOHN W.
Field experiments were conducted in 1996 and 1997 to evaluate the tolerance of imidazolinone-resistant (IR) and non-IR corn cultivars to preemergence (PRE) and postemergence (POST) treatments of diclosulam. Crop injury was evaluated early- (5 to 6 wk after planting [[WAP]]), mid- (10 to 11 WAP), and late-season (13 to 15 WAP). Early-season injury of IR corn was no more than 12%% in systems that included diclosulam PRE or POST at 18, 27, or 36 g ai/ha. Early-season injury of non-IR corn ranged from 85 to 89%% in systems that included diclosulam PRE at any rate. At the mid-season evaluation, crop injury to IR corn was 1%% or less. Non-IR corn was injured 73 to 94%% in systems that included diclosulam PRE, while systems that included diclosulam POST caused 45 to 58%% injury at mid-season. At the late-season evaluation, non-IR corn was injured 56, 88, and 96%% with diclosulam PRE at 18, 27, and 36 g/ha, respectively, whereas systems that included diclosulam POST had 11 to 14%% injury. Injury to IR corn from diclosulam PRE or POST was not apparent at the late-season evaluation. Weed-free yield of IR corn treated with diclosulam was 6,490 to 6,850 kg/ha and was equivalent to or better than yield from IR corn treated only with atrazine plus metolachlor PRE. Yield from non-IR corn treated with any diclosulam-containing system did not exceed 3,770 kg/ha.Nomenclature: Atrazine; diclosulam; metolachlor; corn, Zea mays L. ‘‘Pioneer 3242’’, ‘‘Pioneer 3223’’.Additional index words: Crop injury, crop tolerance, discoloration, stand reduction, stunting.Abbreviations: ALS, acetolactate synthase [[EC 4.1.3.18]]; IR, imidazolinone-resistant; POST, postemergence; PRE, preemergence; WAP, weeks after planting.
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