TITLE:
Linuron Biologically Effective Dose for Glyphosate-Resistant Giant Ragweed (Ambrosia trifida L.) Control in Soybean (Glycine max L.)
AUTHORS:
Kimberly D. Walsh, Nader Soltani, Lynette R. Brown, Peter H. Sikkema
KEYWORDS:
Giant Ragweed, Glyphosate-Resistant, Linuron, Soybean
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.18,
August
18,
2014
ABSTRACT: Glyphosate-resistant (GR) giant ragweed (Ambrosia trifida L.) was first identified in Canada in 2008 and has
since been found throughout southwestern Ontario. Six field trials were
conducted over a two-year period (2012, 2013) on Ontario farms with GR giant
ragweed to evaluate the efficacy of linuron applied pre-plant (PP) in soybean (Glycine max (L.) Merr.). The dose
required for 50%, 80%, and 95% GR giant ragweed control was 1238, 2959, and
6018 g·ai·ha-1 four weeks after application (WAA), respectively. The
linuron dose needed for 50%, 80%, and 95% reduction in density was 1554, 3181,
and 5643 g·ai·ha-1 and 1204, 2496, and 4452 g·ai·ha-1 for
dry weight, respectively. Application of
7874 g·ai·ha-1 linuron was needed to obtain soybean yields that were
90% of the weed-free control; approximately 3.5 times the maximum field
recommended dose. To achieve 95% and 98% yields, greater than 8640 g·ai·ha-1 linuron was required. Application of linuron plus glyphosate PP in soybean will
help to control GR giant ragweed as well as reduce GR selection pressure.