TITLE:
Influence of late emerging weeds in glyphosate-resistant corn
AUTHORS:
Nader Soltani, Robert E. Nurse, Eric Page, Wesley J. Everman, Christy L. Sprague, Peter H. Sikkema
KEYWORDS:
Biomass; Density; Glyphosate-Resistant Corn; Leaf Stage; Maize; Plant Height; Yield
JOURNAL NAME:
Agricultural Sciences,
Vol.4 No.6,
June
27,
2013
ABSTRACT: Fifteen field trials were conducted from 2009 to 2011 in Ontario, Canada
and Michigan, USA to determine how long glyphosate-resistant corn needs to be
kept weed-free after emergence to prevent yield loss. Data were separated into
two environments based on when yield loss first occurred after glyphosate
application. In Environment 1 (4/15 sites) yield was not reduced when corn
was kept weed-free until the 4-leaf stage. However, in Environment 2 (11/15
sites) there was no yield loss when corn was kept weed-free up to the 2-leaf
stage. The most prominent weeds were velvetleaf, redroot pigweed, common
ragweed, common lambsquarters and foxtail species. While later emerging weeds
did not necessarily impact corn yield, weeds emerging after the 2- and 4-leaf
corn stage likely produced seed that was added to the soil seed bank. Weeds
emerging after 6-, 8-, and 10-leaf corn growth stages were small (low biomass/seedlings)
and most likely did not reach reproductive maturity. Based on this research,
corn must be maintained weed-free up to the 4-leaf stage. Any weeds emerging
after that did not influence corn yield.