TITLE:
Volunteer Glyphosate and Glufosinate Resistant Corn Competitiveness and Control in Glyphosate and Glufosinate Resistant Corn
AUTHORS:
Nader Soltani, Christy Shropshire, Peter H. Sikkema
KEYWORDS:
Crop Injury, Competitiveness, Control, Density, Yield, Zea mays
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.5,
April
9,
2014
ABSTRACT: Glyphosate and
glufosinate resistant (RR/LL) volunteer corn has become a problem when hybrid
RR/LL corn follows hybrid RR/LL corn in the rotation. A total of six field
trials were
conducted over a three-year period (2008 to 2010) in southwestern Ontario to 1) evaluate the
competitiveness of volunteer RR/LL corn in hybrid RR/LL corn, and 2) determine
how to control volunteer RR/LL corn in hybrid RR/LL corn. The predicted
volunteer RR/LL corn density to
reduce hybrid RR/LL corn yield by 5%
was 1.7 volunteer RR/LL corn plants m－2. There was no crop injury in hybrid RR/LL corn with herbicides evaluated at 1 and 2
WAA except for rimsulfuron(15 g·ai·ha－1) and foramsulfuron (35 g·ai·ha－1) which caused as much as 5% and 11% injury in
hybrid RR/LL corn, respectively. Glyphosate (1800 g·ae·ha－1), glufosinate(500
g·ae·ha－1) and glyphosate +
glufosinate (1800 + 500 g·ae·ha－1) provided up to
18%, 10% and 21% control of volunteer RR/LL corn, respectively. The POST
application of rimsulfuron (15 g·ai·ha－1), nicosulfuron (25
g·ai·ha－1),
nicosulfuron/rimsulfuron (25 g·ai·ha－1), foramsulfuron
(35 g·ai·ha－1), and
primisulfuron/dicamba (166 g·ai·ha－1) did not provided
any control of volunteer RR/LL corn. Glyphosate and glyphosate + glufosinate
reduced volunteer corn density 26% and 30%, respectively. The other herbicides
evaluated did not reduce volunteer RR/LL corn density compared to the weedy
control. None of the herbicides evaluated reduced volunteer RR/LL corn cob
numbers compared to the weedy control. Glyphosate + glufosinate applied POST
reduced volunteer RR/LL corn yield 35% compared to the weedy control but other
herbicides evaluated caused no reduction in volunteer RR/LL corn yield compared
to the weedy control. Glyphosate applied POST resulted in hybrid RR/LL corn
yield equivalent to the weed free control but all other herbicide treatments
resulted hybrid RR/LL corn yield equivalent to the weedy control. This research
concludes that volunteer RR/LL corn can be very competitive with RR/LL hybrid
corn. None of the herbicides evaluated provided adequate control of volunteer
RR/LL corn in hybrid RR/LL corn.