|Koger iii, Clifford|
Submitted to: Weed Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/19/2006
Publication Date: 7/5/2007
Citation: Koger Iii, C.H., Price, A.J., Faircloth, J.C., Wilcut, J.W., Nichols, S.P. 2007. Effect of residual layby herbicides on weed control and cotton (hossypium hirsutum) yield in glyphosate- and glufosiate-resistant cotton.. Weed Technology. 21:378-383 Interpretive Summary: Full-season weed control is vital for optimizing cotton yields. Glyphosate and glufosinate do not provide residual weed control in glyphosate- and glufosinate-resistant cotton. Thus, residual herbicides that are registered for use in cotton when applied with glyphosate or glufosinate may help to provide season-long weed control in cotton production systems. The addition of a residual herbicide to glyphosate or glufosinate improved overall control of several weed species and reduced weight of weeds present at time of cotton harvest. Reducing weeds at time of cotton harvest will help to improve quality of cotton and reduce problems associated with harvesting a weedy crop.
Technical Abstract: Field experiments were conducted to evaluate weed control and cotton response to glyphosate or glufosinate applied alone or with residual LAYBY herbicides in glyphosate- and glufosinate-resistant cotton. Glyphosate (0.86 kg ae/ha) or glufosinate (0.47 kg ai/ha) were applied alone over-the-top of glyphosate- or glufosinate-resistant cotton early postemergence (EPOST) followed by (fb) late postemergence (LPOST) fb one of the herbicides applied either alone or with a residual herbicide at LAYBY. Residual herbicides evaluated included prometryn (1.12 kg ai/ha), fluometuron (1.12 kg ai/ha), diuron (1.12 kg ai/ha), oxyfluorfen (1.12 kg ai/ha), pendimethalin (1.0 kg ai/ha), prometryn + trifloxysulfuron (1.33 kg ai/ha + 12 g ai/ha), or linuron + diuron (0.56 + 0.56 kg ai/ha). Glyphosate-and glufosinate-based weed management systems with and without residual LAYBY herbicides resulted in little to no injury to cotton. Three applications of glyphosate or glufosinate alone provided better full-season control of most species when compared to two applications of either herbicide. The addition of a residual herbicide to glyphosate or glufosinate at LAYBY did not improve cotton yields, but did improve overall control of barnyardgrass and yellow nutsedge and reduced weed dry biomass present at time of cotton harvest when compared to three applications of glyphosate or glufosinate alone.