Crop Scouting Crucial in Managing the Unpredictability of Cutworms


Cutworm outbreaks are incredibly unpredictable, pest management biologist Jennifer Otani told delegates of Agronomy Update in Red Deer last month.

The insect can overwinter as eggs, larvae, or pupae, and scientists don’t yet have a good understanding of the survivability of the various stages, let alone the almost twenty species we’re dealing with across the prairies. Then there’s the fact that some of those species have higher degrees of host plant preference than others, leading to variations in crop susceptibility.

They’re adaptable, said Otani, and they can consume many different crops.

In the past, cutworm populations were partially managed with summerfallow in rotations. As the industry has largely left that practice in the dust, the onus has shifted even more to proper management tecniques, specifically, regular and timely crop scouting.

“We’re really encouraging growers to go out early,” said Otani. “Don’t look at a field that’s not growing well and leave it. And certainly any of those blank areas, if you’re starting to see that emerge in fields, go investigate — get digging, really.”

Jennifer Otani, pest management biologist with Agriculture and Agri-Food Canada, in conversation with RealAgriculture’s Debra Murphy.

Otani’s Tips for Scouting Cutworms:

  1. Get out there early in the spring.
    According to Manitoba Agriculture, crop seedlings should be inspected weekly (at least) from mid-May to mid-June.
  2. Go later in the evening or earlier in the morning.
  3. Focus on the crowns/base of plants.
  4. Stay in the top two inches of soil, only going deeper if the soil is incredibly dry.
  5. Watch for areas where birds are accumulating on the field.
  6. Use nominal thresholds or economic thresholds.
  7. Do something when damage levels warrant a response.

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