Weed management in furrow-irrigated corn is challenging because of weed emergence associated with each irrigation event. Residual herbicides that provide extended in-season control of a broad spectrum of weeds would be beneficial to producers in this system. Field experiments were conducted in 2005 and 2006 in Yellowstone County, Montana, to evaluate KIH-485 for the control of velvetleaf, kochia, and wild buckwheat in furrow-irrigated corn. KIH-485 was applied at three rates (166, 209, and 250 g ai/ha) and two timings (PRE and POST) and compared to standard rates of S-metolachlor, acetochlor, and pendimethalin. All PRE treatments were applied alone, whereas POST treatments were combined with 1,261 g ae/ha of glyphosate. All rates of KIH-485 applied PRE controlled velvetleaf and kochia 88% or greater at 4 mo after planting (MAP). Wild buckwheat was controlled 89% or greater with the high rate of KIH-485 applied PRE, which was superior to control achieved with any other PRE herbicide treatment. Velvetleaf, kochia, and wild buckwheat were controlled 91% or greater when any herbicide treatment was combined with glyphosate. Corn treated with KIH-485 applied at 209 g ai/ha PRE produced yield that was similar to that produced by the weed-free control in both years.

Nomenclature: Acetochlor; glyphosate; KIH-485, 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)methylsufonyl]-4,5-dihydro-5,5-dimethylisoxazole; S-metolachlor; pendimethalin; kochia, Kochia scoparia (L.) Schrad. KCHSC; velvetleaf, Abutilon theophrasti Medik. ABUTH; wild buckwheat, Polygonium convolvulus L. POLCO; corn, Zea mays (L.) ZEAMX