Flea beetles and diamondback moth

A common pest insect in canola, the diamondback moth adults blow in from the southern United States each spring with their larval offspring – and subsequent generations – can cause varying amounts of feeding damage on green canola tissues throughout the growing season. There are relatively good monitoring options for this insect, from wind trajectory models, to pheromone traps in addition to in field scouting. In combination with economic threshold considerations, there are good tools for making management decisions.

• Adults that arrive in the spring mean there will be multi-generations and a higher risk of economic damage. Be aware of provincial agricultural and Prairie Pest Monitoring Network early warnings.
• Pheromone traps detect arrival of moths in the spring but are NOT to be used for economic thresholds.
• July and August is the main time to scout fields for potential damage and/or larvae. Increasing scouting if notable insect feeding is observed.
• When scouting: remove plants in an 0.1 square metre area (about 12 square inches), then vigorously shake the plants onto a clean surface and count the number of larvae dislodged from the plants.
• Use economic thresholds, which vary by the plant stage, as thresholds ensure only warranted insecticide applications are made. This minimizes the impact on beneficial insects. An insecticide application may be considered:
• if larvae exceed 100-150 per square metre (10-15 larvae per square foot) on immature to flowering plants.
• there are 200-300 larvae per square metre (20-30 larvae per square foot) at the late flowering or pod stage.
• at seedling stage when there has been 25-33 per cent defoliation and larvae are still present on the plant.
• Parasitoids and other biological controls often collapse infestations of diamondback moth prior to economic damage.
• Control brassicaceous weeds including volunteer canola (which are host plants for the insect)
• Check out canola production-related research on diamondback moths in the Canola Research Hub.