North Central Canola Research Program


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Canada Thistle Control in Canola

Canada Thistle Control in Canola
Brian Jenks, North Dakota State University - $8,900

Canada thistle is a problem throughout North Dakota and even just a few plants can reduce yields. For example, a North Dakota study showed that 20 plants per m2 reduced spring wheat yields by 22%. A Canadian study showed a 10% yield reduction with 20 plants per m2, while in Montana yields were reduced by 45%. In canola, Canadian data indicates that 20 plants per m2 will reduce canola yields approximately 24%.

Roundup provides one option for controlling Canada thistle. Stinger effectively effectively control Canada thistle, but is very expensive and has a limited weed spectrum relative to Roundup. Research is needed to determine the optimum application rate and timing for season-long and long-term Canada thistle control.


1. Determine the short and long term effect of Roundup rate on Canada thistle control.
2. Determine the short and long term effect of application timing on Canada thistle control.
3. Compare Roundup vs. Stinger for Canada thistle control.
4. Determine the long-term effect of herbicides in a canola-wheat-canola rotation.

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