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1 April 2009 Preemergence Herbicide Efficacy and Phytotoxicity in Grain Sorghum
Patrick W. Geier, Phillip W. Stahlman, David L. Regehr, Brian L. Olson
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Field studies conducted from 2005 to 2007 in Kansas compared the effects of KIH-485 and flufenacet to acetochlor and s-metolachlor applied PRE in grain sorghum. All treatments were combined with 1.12 kg/ha of atrazine for broadleaf weed control. KIH-485 and flufenacet, each at one time (1×) and two times (2×) the labeled rates, controlled large crabgrass 55 to 76% in 2005 and 94% or more in 2006 and 2007. In 2005, all herbicides controlled shattercane less than 20%, and only KIH-485 at the 2× rate controlled shattercane more than 70% in 2006 and 2007. Averaged over herbicides, green foxtail was controlled 98% in 2005, 77% in 2006, and 79% in 2007. Most herbicides controlled foxtail 86% or more when averaged over experiments, however, s-metolachlor at 1×, flufenacet at either rate, or atrazine alone did not. Sorghum was not stunted with KIH-485 or flufenacet in two of seven experiments. However, sorghum growth was reduced 23 to 54% with the 2× rates of KIH-485, flufenacet, or acetochlor in four experiments. Compared to the weed free control, sorghum stand establishment was reduced 18% with the 2× rate of flufenacet at Colby in 2006. At Hays in 2005, stand reductions occurred with acetochlor or KIH-485 at the 2× rates and either rate of flufenacet. Averaged over experiments, grain yields were reduced 9 and 10% with KIH-485 and flufenacet at the 2× rates, respectively. Where precipitation was greatest during the 2 wk following herbicide application, weed control was the best with these herbicides, but sorghum injury was also greatest.

Nomenclature: Acetochlor; atrazine; flufenacet; KIH-485, 3-[(5-difluoromethoxy-1-methyl-3-trifluoromethylpyrazol-4-yl)methylsulfonyl]-4,5-dihydro-5,5-dimethylisoxazole; s-metolachlor; green foxtail, Setaria viridis (L.) Beauv. SETVI; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; shattercane, Sorghum bicolor (L.) Moench SORVU; grain sorghum, Sorghum bicolor (L.) Moench.

Patrick W. Geier, Phillip W. Stahlman, David L. Regehr, and Brian L. Olson "Preemergence Herbicide Efficacy and Phytotoxicity in Grain Sorghum," Weed Technology 23(2), 197-201, (1 April 2009).
Received: 29 August 2008; Accepted: 1 February 2009; Published: 1 April 2009

Crop injury
stand loss
weed control
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