Posted March 3, 2025 | By: Gary Topham, Agronomic Innovation Manager, Manitoba Division

While resistant kochia and wild oats are always a concern, volunteer canola is another weed many growers tend to overlook.

According to the Canola Council of Canada, even under normal harvest conditions with a properly set combine, growers can lose one or more bushels of canola seed.
However, the 2024 canola harvest was anything but normal.

Excessive rain throughout the summer led to uneven crop maturity across numerous fields. Even with pod shatter or harvest management canola varieties, there were additional losses from pod drop or pod shatter. To make matters worse, three days of hurricane winds in the first week of October caused extra shattering losses in fields that were still not harvested.

Typically, a large percentage of volunteer canola germinates in the fall and is killed by frost. But because of the late harvest and declining fall soil temperatures, less volunteer canola germinated than usual. This means a significant number of volunteer canola will germinate this spring.

To put the numbers in perspective: a single bushel contains about 4.25 million seeds. When we determine how many seeds in a bushel (about) With 43,560square feet in an acre, losing one bushel at harvest translates to roughly 100 volunteer canola seeds per square foot. A two-bushel loss doubles that to 200 volunteer canola seeds per square foot. Some fields affected by the wind saw losses exceeding 10 bushels per acre.

Weed removal calculators highlight the impact this could have on yield. If a cereal crop emerges three days before the volunteer canola at a density of one plant per square foot, there is a yield loss of 9-10%. If the volunteer canola emerges three days prior to the cereal crop, those yield losses can nearly triple to 30%.

There is no right or wrong approach to controlling your volunteer canola, but now is the time to start planning. Consider pre-seed, post-seed pre-emerge and in-crop control options that align with your farm management practices.