Volunteer Canola Control

The addition of winter and spring canola to the crop rotations of Eastern Washington has provided growers with increased options for weed control, particularly for some of the most troublesome grass weeds such as Integrated Management of Downy Brome in Winter Wheat, feral rye, and Italian ryegrass. However, volunteer canola, particularly volunteer Roundup Ready^® canola, has become a troublesome weed of its own.

Volunteer canola has been problematic in western Canada for a while. I recently exchanged some email messages with Eric Johnson with the University of Saskatchewan in Saskatoon, Canada on this topic. The following are some of the thoughts he shared on the topic of the pre-seed burndown of volunteer canola.

“Phenoxy herbicides like 2,4-D or MCPA work quite well and were the most commonly used tank-mix partner with glyphosate following the introduction of RR canola.  Issues with glyphosate-resistant kochia, cleavers, wild buckwheat and other hard-to-control broadleaf weeds have led producers to use other options.

Group 2 herbicides like tribenuron (Express and other trade names) or florasulam (active ingredient found in Orion, Quelex, Starane Flex, and Goldsky) provide effective control of volunteer canola.  Some growers don’t like that these products are slower acting; thus, they tend to choose a Group 14 herbicide.

Group 14 herbicides like carfentrazone (Aim EC) is effective on very small canola (1-2 leaf stage) but fails on larger (> 4-leaf) plants. Control is greatly improved if carfentrazone is mixed with a phenoxy herbicide, for example 2,4-D or MCPA.  Saflufenacil (Sharpen) has become quite popular as well and is effective on a wide array of growth stages. Pyrafluen-ethyl (Venue and Vida), if mixed with MCPA or 2,4-D is also extremely effective.”

Planting a grass crop like wheat or barley after canola provides additional opportunities for controlling volunteer canola that emerges after the pre-seed burndown or survives the pre-seed burndown. The latter being more difficult to control than the former. Many of the Group 2 herbicides provide effective control of canola. These include products such as Affinity BroadSpec, Express, Harmony, Ally XP, Ally Extra, Peak, Amber, Goldsky, Finesse Cereal and Fallow, and many similar generic herbicides. Adding a phenoxy herbicide like 2,4-D, MCPA, or halauxifen (an active ingredient in Quelex and Tarzec) can improve volunteer canola control in wheat. Talinor and Huskie herbicides also provide effective control of volunteer canola. Although volunteer canola is not listed in the Winter Wheat Herbicide Efficacy Tables, located on the WSU Wheat and Small Grains website, you can get a good feel for the most effective herbicide options by clicking on the wild mustard column and looking at those treatments that are listed as providing excellent (E) control.

The addition of canola to the cropping systems of Eastern Washington brings many agronomic and weed control benefits. However, managing volunteer canola, particularly Roundup Ready® canola, requires a little more planning and effort than growers have been accustomed to prior to the introduction of canola into our cropping systems.

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