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The distribution and control of glyphosate-resistant waterhemp (Amaranthus tuberculatus var. rudis) in soybean (Glycine max) in Ontario

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dc.contributor.advisor Sikkema, Peter
dc.contributor.advisor Robinson, Darren
dc.contributor.author Schryver, Mike G.
dc.date.accessioned 2017-04-28T20:08:17Z
dc.date.available 2017-04-28T20:08:17Z
dc.date.copyright 2017-03
dc.date.created 2017-03-16
dc.date.issued 2017-04-28
dc.identifier.uri http://hdl.handle.net/10214/10331
dc.description.abstract Field surveys were conducted in 2014 and 2015 to gain an understanding of the distribution of glyphosate-resistant waterhemp in Ontario. Following the first confirmed case on Walpole Island, Lambton County in 2014, 39 additional glyphosate-resistant populations were discovered in 2015. In addition to glyphosate, waterhemp populations were found to be resistant to group 2 (imazethapyr) and group 5 (atrazine) herbicides in greenhouse experiments at an incidence of 100% and 75%, respectively. Of the 49 collected waterhemp samples, 61% were resistant to all three herbicide groups (2, 5, and 9). In addition, six greenhouse and thirty-six field experiments were conducted over a two-year period (2015 and 2016) at four locations to determine the biologically effective rate of glyphosate, and at two locations to evaluate the efficacy of pre-emergence and post-emergence herbicides for the control of glyphosate- resistant waterhemp in soybean. Determination of the biologically effective rate of glyphosate revealed a resistance factor in the greenhouse and field of 4.8 and 28, respectively. Among the 14 pre-emergence herbicides available for use in soybean that were tested, pyroxasulfone/flumioxazin, pyroxasulfone/sulfentrazone, and s-metolachlor/metribuzin all provided greater than 90% control. A two- pass weed control strategy was found to be the most efficacious, with a residual pre-emergence herbicide followed by an alternative to glyphosate applied postemergence for waterhemp escapes providing excellent control in all control systems tested. en_US
dc.description.sponsorship Monsanto, Syngenta, Bayer, DuPont, BASF, Valent, Dow, Pioneer en_US
dc.language.iso en en_US
dc.rights Attribution-NoDerivs 2.5 Canada *
dc.rights.uri http://creativecommons.org/licenses/by-nd/2.5/ca/ *
dc.subject Research Subject Categories::FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING::Plant production en_US
dc.subject glyphosate en_US
dc.subject resistance en_US
dc.subject multiple-resistance en_US
dc.subject glyphosate-resistance en_US
dc.subject waterhemp en_US
dc.subject common waterhemp en_US
dc.subject dose response en_US
dc.subject biologically effective rate en_US
dc.subject management en_US
dc.subject pyroxasulfone en_US
dc.subject flumioxazin en_US
dc.subject S-metolachlor en_US
dc.subject weed management en_US
dc.subject distribution en_US
dc.title The distribution and control of glyphosate-resistant waterhemp (Amaranthus tuberculatus var. rudis) in soybean (Glycine max) in Ontario en_US
dc.type Thesis en_US
dc.degree.programme Plant Agriculture en_US
dc.degree.name Master of Science en_US
dc.degree.department Department of Plant Agriculture en_US
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Attribution-NoDerivs 2.5 Canada Except where otherwise noted, this item's license is described as Attribution-NoDerivs 2.5 Canada