P&PDL Picture of the Week for
June 13, 2005

Roundup Ready Canola

Glenn Nice, Weed Diagnostician, Botany & Plant Pathology Department, Purdue University

I was recently called out to a field in Tippecanoe county regarding a weed that had possibly survived an application of glyphosate.  When I got out there, I saw sick and dying thistles, grasses that were mere carcasses, and the typical sight of a field a couple of weeks after a glyphosate application.  Except for one thing - spotted through out the field there was this perfectly healthy mustard doing very well.  Upon closer inspection the mustard turned out to be canola.  The fact that it was not even sick from a glyphosate application suggested that it was possibly a Roundup Ready canola.

As to how it got into this field and without a passport is still being pondered, but it may have come from some contaminated seed.  Although unlikely, if this should happen to you, what options are open to you?  In 2004, Brian Jenks, Denise Markle, and Gary Willoughby of North Dakota State University did some work on how to control it in corn and soybeans (http://www.ag.ndsu.nodak.edu/minot/weeds/).  All treatments below included the appropriate surfactants that were required by the labels.

PRE applications of Balance Pro (3 fl oz/A) provided excellent control of canola in corn.  POST applications of Steadfast (0.75 oz/A), Accent (0.5 oz/A), and Option (1.5 oz/A) provided above 95% control.  The applications of 2,4-D (0.5 pt/A) amine and Distinct (4 oz/A) controlled canola in the high 80’s when applied at the third-leaf stage; however, efficacy significantly dropped when applied to canola at the sixth-leaf stage.  Atrazine POST did not provide adequate control of canola.

In soybean, Valor (2.5 oz/A) and Extreme (1.5 pt/A) provided excellent control PRE achieving greater than 95% control.  Raptor (4 fl oz/A) and Flexstar (0.75 pt/A) controlled canola greater than 95% POST, regardless if applications were applied at the third-leaf or sixth-leaf stage of canola.  Treatments using Basagran (0.5 pt/A) and Cobra (6 fl oz/A) provided good control of third-leaf canola, but had a decrease in control when applied to sixth-leaf canola.

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Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service