(This is something to consider for next year.) For lots more on species identification, use AAFC’s Cutworm Pests of Crops on the Canadian Prairies or read this Canola Watch article. Pale western cutworms are primarily subterranean feeders, which means a systemic product such as a cutworm seed treatment may provide the best protection. Underground-feeding cutworms are less likely to encounter spray, for one thing. Reason two: To identify the cutworm species present as this can influence management decisions. Mechanical problems with the drill can lead to missing rows, and while it might seem obvious to identify a mechanical issue, cutworms will often follow along the loose worked soil of seed row. Note that cutworms often clean out all the plants and weeds in a patch, while disease may be more plant specific. While scouting around patches, check roots and seeds for signs of rot and infection. For example, fungal seedling diseases can cause seed and seedling decay that can lead to patches of missing plants. Reason one: To confirm that cutworms are the cause. Cutworms could be the cause.Ĭlipped plants are another sign of cutworms in action. Dry springs can improve survival of larvae.ĭig around the perimeter of patches like this. The most common species in Western Canada – redbacked and pale western – overwinter as eggs, and may not be as susceptible to saturated soils. Wet springs can increase cutworm mortality due to pathogens, but this tends to affect those species that overwinter as larvae more than those that overwinter as eggs. In southern Alberta, for example, the winters of 2014-16 were unusually mild, which meant high winter survival. Weather conditions can influence the survival of overwintering eggs and larvae. A long relatively dry fall can also allow for maximum egg laying opportunities, and may result in a more widespread outbreak. Females also prefer loose worked soil for egg laying. These flowers attract the adult moths, which lay their eggs in these areas. In general, fields that had flowering plants (crops or weed patches) in August or September of the previous year may have higher cutworm counts. It often has to do with adult attractants at the time of egg laying. Cutworm outbreaks are hard to predict and numbers can vary significantly field to field.
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