Agronomy •  2022-12-19

Controlling volunteer canola with a program approach

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Just about all canola acres in western Canada are seeded to varieties with herbicide tolerant traits. Couple that with the fact that the canola seeded acreage in this country averages 20 million acres annually1, and you can see how volunteer canola shot up most “Top 10” weeds lists over the last decade or so.

Farmers who are growing Enlist E3 soybeans have exceptional volunteer canola control options when they use the program approach. This starts with pre-seed burndown herbicides (with alternate modes of action to the three main canola systems and residual activity) followed by Enlist herbicides in-crop to catch stragglers. It’s a two-step weed management plan that protects the yield potential of Enlist E3 soybeans using a multi-mode-of-action (MMOA) strategy.

The problem: Almost all canola seeded today is tolerant to one of three herbicides: Group 9 (Roundup Ready®), Group 10 (Liberty Link®) or Group 2 (Clearfield®). And for an added level of complexity, some newer hybrids have both Roundup Ready and Liberty Link traits stacked into one plant. Inevitably, volunteers from all systems show up in the following years, sometimes in the same field at the same time, making herbicide selection something of an exercise in musical chairs.

Untreated volunteer canola is an excellent host for the seedling disease complex, which affects all crops, plus it can germinate throughout the season, making application timing a critical factor.

Early weed removal and choosing herbicides with multiple modes-of-action are key when it comes to effective volunteer canola control.

Controlling volunteer canola with the Enlist weed control system: There are many cultural solutions to volunteer canola that should be used along side a good herbicide regimen. These include good rotations to reduce seed accumulation and tillage. Light tillage in the fall has been shown to increase canola germination and thus provide a greater kill rate.

Volunteer canola is extremely sensitive to 2,4-D, making the Enlist weed control system, which includes two 2,4-D-based herbicide options, a useful tool for those growing Enlist E3 soybeans. These varieties are tolerant of glyphosate, glufosinate and 2,4-D and can be safely sprayed with:

  • Enlist Duo™ herbicide a convenient proprietary blend of 2,4-D choline (Group 4) and glyphosate (Group 9).
  • Enlist™ 1 herbicide a stand-alone 2,4-D choline formulation that can be tank-mixed with Liberty® 200 SN (Group 10) or glyphosate.

Both herbicides come with Colex-D technology for near-zero volatility and low drift so it stays where it’s sprayed.

The program approach to control volunteer canola: This two-pass system uses multiple modes-of-action to effectively control volunteer canola, in Enlist E3 soybeans.

  1. Start with a residual herbicide as a pre-seed burndown. Apply Heat® LQ (Group 14 saflufenacil), Valtera (Group 14 flumioxazin) or Aim® EC (Group 14 carfentrazone-ethyl) as a pre-seed burndown. Applying a Group 14 herbicide in the first pass provides a mode of action all volunteer canola is susceptible to and leaves you free to use a Group 9 or 10 herbicide in the second pass.
  2. Apply Enlist Duo or Enlist 1 herbicide at post-emergence. Depending on your weed spectrum, you can apply Enlist Duo (which contains glyphosate) or Enlist 1 in a tank mix with glufosinate to catch late-emerging volunteer canola. The Enlist herbicides are perfect for this task because they offer a wide application window – up to R2 (full flower) when glyphosate is used, and up to R1 (beginning of flower) when glufosinate is used.

Key takeaways: Volunteer canola is ubiquitous across the Prairies, and it almost always carries some herbicide tolerant trait, albeit a weaker one since this tends to diminish in second and third generation plants. Volunteer canola growing from untreated seeds can be a vector for early season disease and insects, so it’s key to remove these weeds as early as possible.

Cultural control methods should be included in an integrated weed management plan, and always use an MMOA approach to herbicide selection when aiming to control volunteer canola.


1Canola Council of Canada.