The new generation of crucifer flea beetles is emerging, and feeds on the green foliage and developing pods. Field reports of significant feeding injury have been observed near Napoleon in south central ND. Usually the upper or younger pods and later seeded crops are most impacted. This feeding damage results in poor seed fill, premature pod drying, shriveled seeds, or pod shattering, and provides an entry point for fungal growth within pods in damp weather. However, it is usually not economic since most of the yield comes from the lower pods. If canola is under drought stress, damage could be more severe. There is no established threshold for managing flea beetles this late in crop development. If you are considering spraying an insecticide, it is important to observe the different Pre-Harvest Intervals (PHI) of the insecticides registered in canola. Any pyrethroid insecticide will offer good control of flea beetles and residual activity until harvest. Examples of active ingredients and PHI include: bifenthrin – 35 days PHI (Sniper, Tundra EC, Brigade 2EC, others); deltamethrin – 7 days PHI (Delta Gold); gamma-cyhalothrin – 7 days PHI (Declare); lambda-cyhalothrin – 7 days PHI (Grizzly Too, Silencer, Warrior II, others) and zeta-cypermethrin – 7 days PHI (Mustang Maxx).
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