Cutworms

Usually the first signs of a cutworm problem are bare patches appearing in the crop, seemingly overnight. Upon further inspection you will find healthy plants cut off at ground level or just below the surface. Some species of cutworm may also be leaf feeders and cause damage all the way up the plants. Cutworms are nocturnal larvae that spend their days buried in the soil, this may make it difficult to scout for them. The two main species found here are the Redbacked, which is most common, and the Pale Western with occasionally some glassy varieties showing up in fields of timothy and fescue. There are some cutworms in most fields every year but we have had very few serious outbreaks in the County.

What To Look For

Cutting Field damage
Redbacked Cutworm and pupae Pale Western Cutworm

Prevention

The life cycle and habits of the cutworm make them a little more difficult to manage in canola crops. Being nocturnal and feeding overnight, the larvae pose a challenge for chemical control. However, newer technology in spray equipment allows night spraying to be a feasible option for control of cutworms and reduces pesticide exposure to beneficial insects. There are some other considerations when dealing with these pests:

  • Scout fields regularly to provide early detection
  • Know which species you are dealing with
  • Over time, beneficial insects and diseases will lessen the amount of cutworm infestation
  • Apply recommended insecticide at optimum timing using high rates of spray volume to ensure coverage