RealAg Radio – RealAgriculture
Canola School: Flea Beetles Bite, Cutworms Hide — What Growers Need to Know
Why It Matters
Understanding and promptly addressing cutworm and flea beetle pressure is critical for protecting canola yields during the vulnerable seedling stage, a period that can set the tone for the entire season. With pest outbreaks being sporadic and climate‑driven, growers need practical scouting tips and treatment thresholds to make timely, cost‑effective decisions that safeguard their crops.
Key Takeaways
- •Cutworms cause patchy damage; flea beetles cause widespread feeding.
- •Scout early: 25% flea beetle threshold, look for bare patches.
- •Seed treatments essential; add foliar spray if thresholds exceeded.
- •Rely on regional history; neighbor outbreaks signal higher risk.
- •Parasitoid wasp attacks adult flea beetles, but impact limited.
Pulse Analysis
Early‑season canola growers face two of the most unpredictable pests: cutworms and flea beetles. Both appear as seedlings emerge, but their damage patterns differ. Cutworms create irregular, bare patches as nocturnal larvae chew seedlings at the soil line, while flea beetles produce characteristic shot‑hole feeding across larger field areas. Understanding these distinctions is crucial for timely intervention, especially as weather shifts toward hotter, drier conditions that can exacerbate infestations. The conversation with Dr. Boyd Morey highlights why integrated pest management (IPM) must start the moment the seed is in the ground.
Effective scouting hinges on clear action thresholds. For flea beetles, a 25 % infestation rate—measured by the proportion of seedlings showing shot‑hole damage—triggers a foliar insecticide application. Cutworm scouting focuses on identifying patchy die‑back and physically locating larvae in the topsoil. Seed treatments remain the first line of defense for both pests; many Alberta producers already use neonicotinoid‑based treatments, and those with recurring problems may add a second‑generation product. When thresholds are breached, a targeted foliar spray can protect the crop without over‑application, preserving both yield potential and environmental stewardship.
Decision‑making relies heavily on regional experience. Growers should review past outbreak data, especially from adjacent fields, to gauge risk. If neighboring farms reported severe cutworm or flea beetle activity, pre‑emptive seed treatments become more justified. While natural enemies—such as the parasitoid wasp Microcchynis vitati for adult flea beetles—exist, their impact is modest. Dr. Morey’s three‑step recommendation—evaluate seed‑treatment needs, conduct thorough ground scouting, and confirm active feeding before spraying—offers a practical roadmap for Alberta canola producers aiming to safeguard early‑season stands and maximize harvest potential.
Episode Description
Warm conditions may still feel a long way off, but early-season insect pressure is never far behind for canola growers. In this episode of RealAgriculture’s Canola School, University of Alberta associate professor Dr. Boyd Mori joins Amber Bell to speak about two key early threats: cutworms and flea beetles. Both pests target canola at emergence,... Read More
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