Rotations tighten, disease risk rises

While the recommended rotation for disease management is to seed canola once every four years, more growers are using a three-year or two-year rotation. This year we’ve heard more talk of canola on canola. This can cause a rapid build up of disease inoculum in the field, especially for clubroot and blackleg. With tight rotations, canola varieties with resistance to blackleg are not bullet-proof — especially if you grow the same varieties year after year. For growers with tight canola rotations, soil-borne seed and seedling diseases can also get more severe. The longer canola takes to get out of the ground, the more damaging these seedling diseases will be. So seed shallow. Download ourdisease assessment card for management and scouting tips.

Canola on canola can also take a big yield hit. Manitoba crop insurance has data (click here for more) showing that canola seeded on canola stubble yields 83% of the 10-year average canola yield for the province.