Field experiments evaluated halosulfuron and glyphosate for yellow nutsedge control in glyphosate-resistant field corn in 1997 and 1998. Treatments included single and sequential glyphosate applications with or without halosulfuron. Single glyphosate applications provided less than 75% yellow nutsedge control. Sequential applications with at least 1.68 kg ae/ha of glyphosate provided 85% or greater yellow nutsedge control 82 or 115 d after treatment (DAT). Halosulfuron was required to consistently obtain 80% or greater yellow nutsedge control. Nearly all treatments resulted in 90% or greater velvetleaf control 82 or 115 DAT. At the same rating times, giant foxtail control was 95% or greater for sequential glyphosate treatments and treatments containing acetochlor. Corn treated with sequential glyphosate applications containing at least 1.26 kg/ha of glyphosate or containing halosulfuron resulted in greater corn yields than with single glyphosate applications. Halosulfuron was required for consistent yellow nutsedge control, but halosulfuron did not control grasses.
Nomenclature: Acetochlor; glyphosate; halosulfuron; giant foxtail, Setaria faberi Herrm. #3 SETFA; velvetleaf, Abutilon theophrasti Medicus # ABUTH; yellow nutsedge, Cyperus esculentus L. # CYPES; corn, Zea mays L. ‘MON-802 RR’, ‘Dekalb DK493RR’.
Additional index word: Amaranthus retroflexus.
Abbreviations: AMS, ammonium sulfate; DAT, days after treatment; gly-R, glyphosate resistant; LPST, late postemergence; POST, postemergence; PPI, preplant incorporated; PRE, preemergence.
