If you have noticed some bare spots out in your field, specifically on hilltops and in sandy areas, it would be a good idea to check in on your crop. Cutworms have been very hungry over the past few weeks and we have been finding them feeding in an array of different crops.
The redbacked, pale western, darksided, army, and dingy cutworms are the five common species of cutworms that can be found, and cause economic damage in field crops on the prairies. Although some species are more common in certain areas, they all seem to be fairly widespread.
Where To Look
Most fields will have cutworms present in them, but not all will have concerning populations. It is important to scout, watch for any changes, and also monitor for the economic threshold. We usually begin by scouting any hilltops or areas in the field with lighter soil. Cutworms are known to prefer these areas because they are warmer and easier for them to tunnel around in. In these areas of the field, we check for spaces within the row as well as wilted or dead plants in those spaces. This is a telltale sign there are usually cutworms present, as they prefer to move from plant to plant within the row. You will also need to monitor those areas for germination issues or seeding misses, which can also be at fault for the spaces within the row.
Within these gaps in the row, you will need to carefully brush away the soil and locate the pest. Cutworms predominantly feed at night above the ground, and will shelter underground during the day. They are usually just below the soil or trash within the row, but can also hide in the soil between the rows as well. It requires boots on the ground scouting, and can be a very tedious process.
If you check a few spots in the field and cutworm numbers are high, it is important to check what the threshold is for that crop, and determine if it is time for a control option. This will involve checking many different areas in the field to determine whether spot spraying is an option, or if the whole field needs to get sprayed.
How To Control or Manage
On canola seed, you can add a group 28 insecticide treatment like Lumiderm or Fortenza, which will kill any cutworms that feed on the plant after they have germinated. This requires there to be some damage to your crop, but it is an effective option for cutworm control.
Pulses and cereals are more challenging. Corteva has just released a new seed treatment called Lumivia CPL that is a group 28 insecticide, and it can be added to your regular seed treatment to help your crop defend itself against cutworms. Like the canola seed treatments, it also requires feeding and ingestion for control.
If you have not used any of the seed treatment products above, there are also in-crop insecticide options such as Matador and Pounce. Both will give you a similar level of residual activity and will effectively control cutworm infestations.
Tips For Future Planning
Cutworm populations have increased over the last few years and don’t seem to be declining. If you have had cutworm infestations in the past, it is important to take that into consideration for the future. Take note of which fields had higher numbers, and monitor those fields closely in years to come. Also, consider on-seed control options mentioned above for fields that are of concern.
Niki Beingessner CCA, PAg
Sales Agronomist – Yorkton