TITLE:
Distribution of glyphosate and cloransulam-methyl resistant giant ragweed (Ambrosia trifida L.) populations in southern Ontario
AUTHORS:
Joanna Follings, Nader Soltani, Darren E. Robinson, François J. Tardif, Mark B. Lawton, Peter H. Sikkema
KEYWORDS:
Giant Ragweed; Glyphosate; No-Tillage; Resistance; Soybean; Survey
JOURNAL NAME:
Agricultural Sciences,
Vol.4 No.10,
October
23,
2013
ABSTRACT: Giant ragweed is a very competitive weed in row crop production and has
been found to drastically reduce soybean yield. In 2008, giant ragweed was
the first weed species with confirmed resistance to glyphosate in Canada. As of
2010 there were 48 locations with confirmed glyphosate resistant giant ragweed
in Essex, Kent and Lambton counties. In addition, there was suspected
resistance to cloransulam-methyl. The objectives of this research were 1) to conduct
an expanded field survey on the distribution of glyphosate resistant giant
ragweed in Ontario, 2) to determine the distribution of cloransulam-methyl
resistant giant ragweed in Ontario, and 3) to determine the distribution of multiple
resistant (glyphosate and cloransulam-methyl) giant ragweed in Ontario. In
2011 and 2012 giant ragweed seed was collected from 85 field sites in Essex
(16), Kent (34), Lambton (23), Elgin (3), Middlesex (6), Lennox & Addington
(1), Huron (1) and Brant (1) counties. In total there are 34 additional
locations confirmed with glyphosate resistant giant ragweed in Ontario. There
are 11 locations confirmed with cloransulam-methyl resistant giant ragweed and
5 locations with multiple resistance to
both glyphosate and cloransulam-methyl. Glyphosate resistant giant
ragweed has been found in 4 additional counties.