Winter Canola Sensitivity to Herbicides

Producers interested in growing winter canola should consider the herbicide history of their field, and the herbicide options open to them following winter wheat harvest. There are a number of restrictions, and some herbicide labels do not mention safety on canola.

At this time (2024) there is only one winter canola variety that is registered in Ontario and readily available to producers. It is named Mercedes and sold by C&M Seeds. Producers are allowed to bring seed of other varieties in from the US for their own use with the appropriate permits, but should ensure end users will accept those varieties before seed is purchased. Please be aware that Mercedes does not carry a herbicide tolerance trait, and neither do most other available varieties. We do not currently have access to Liberty Link or Roundup Ready winter canola.

Herbicide application options prior to planting of winter canola are somewhat limited. The primary choices are glyphosate, glufosinate (Liberty), clopyralid (Lontrel) and trifluralin (e.g. Treflan) as well as grass control products. Eragon and 2,4-D can cause crop injury and should be avoided in pre-plant burn downs.

There are also many herbicide carry over restrictions, and some products may not be safe for canola for up to 2 years after application.

Herbicide plant back intervals for canola that exceed two growing seasons:

  • 22 months: atrazine; imazethapyr (e.g. Pursuit); metribuzin (e.g. Sencor)
  • 26 months: flumetsulam (e.g. Broadstrike RC)

Winter wheat herbicide plant back intervals for canola:

  • 1 month: 2,4-D; 2,4-DB; Achieve Liquid; bromoxynil (e.g. Pardner); bromoxynil/MCPA (e.g. Buctril M); MCPA
  • 2 months: Boost; Express SG; Refine SG; Refine M
  • 4 months: Truslate Pro
  • 10 months: Barricade M; Enforcer M; Eragon LQ; Infinity; Infinity FX; Pixxaro; Prominex; Trophy; Valtera EZ
  • 11 months: Simplicity GoDri; Varro

Treflan and Lontrel are safe to use post emergence in winter canola, as are a number of grass control products. However, Treflan requires incorporation.

Consult the OMAFRA Crop Protection Hub for more information on herbicide carry over restrictions. Conventional winter and spring canola (i.e. those without herbicide tolerance traits) are the same species and have the same reactivity to herbicides, however they have different planting dates and crop rotations so herbicide carry over intervals should be considered carefully.