A population of four to five plants per square foot provides a canopy that can suppress most broadleaf weeds, especially summer annual weeds. Proper tillage and crop rotations, along with a preplant herbicide such as Treflan, help minimize the amount of damage caused by weeds. It is important to note that canola is sensitive to atrazine, and yield reductions can occur in fields with atrazine carry-over. Insects have not yet caused economic losses of canola in Missouri. This fact could change, however, as more acres of canola are planted.
Insects can attack the plant in the fall and spring.
Common pests include flea beetles, cutworms, aphids, grasshoppers, lygus bugs and various caterpillars. Several diseases pose potential problems for canola in the future. Sclerotinia stem rot is identified by premature death of the plant. Avoiding excessive nitrogen applications and rotating with crops that are not hosts to sclerotinia help reduce this disease. Control of these diseases can be enhanced by planting certified seed and establishing a crop rotation.