TITLE:
Efficacy of POST glyphosate applications in combination with other POST herbicides in glyphosate-resistant corn (Zea mays L.)
AUTHORS:
Kristen E. McNaughton, Lynette R. Brown, Peter H. Sikkema
KEYWORDS:
Glyphosate; Weed Control; Glyphosate-Resistant Corn; POST Application
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.1,
January
6,
2014
ABSTRACT: The use of glyphosate-resistant
corn has facilitated a shift from a reliance on preemergence residual
herbicides to postemergence (POST) herbicides, and in some cases exclusively glyphosate.
Glyphosate is a non-selective herbicide that is relatively slow-acting, which
may allow weeds to continue to compete with corn after application and
potentially decrease crop yield. The addition of several POST corn herbicides,
with some residual control, to an early-season glyphosate application was
examined to determine if the tankmix combination would improve the speed of
weed control compared to glyphosate applied alone. Seven field trials were conducted over three years (2009, 2010 and 2011) near
Ridgetown and Exeter, Ontario. The control of common ragweed was improved 3
days after application (DAA) with three POST glyphosate
tankmixes compared to glyphosate alone. However control was still less
than 55%. Depending on the weed species examined, at 28 DAA two of the
glyphosate tankmix treatments tested provided better common ragweed, common
lambsquarters, or green foxtail control than glyphosate alone. Treatments
providing better weed control at 28 DAA also
typically decreased weed density compared to glyphosate alone.