Insect update: Wireworms and cutworms

Cutworm survey. The Canola Council of Canada is looking for growers willing to collect cutworms for research. Cutworms are an increasing threat to canola and other crops, and growers will benefit from knowing more about this native pest.

At least seven cutworms species can cause economic damage to Western Canadian crops. We often generalize when it comes to cutworms and cutworm management recommendations, but some of these species behave in quite different ways and generalizations can result in costly crop losses.  We have a lot to learn about cutworms. Our current challenge is sourcing and collecting cutworms to know which species are where, when and at what numbers. Read this Cutworm collection letter May16 for more information on how you can help. For every sample submitted, your name will be entered into a draw to be awarded this fall.

Scout for wireworms before seeding. Wireworms can feed on canola in some circumstances, especially in fields that were pasture or hay recently or fields that have had wireworm problems in cereals. Ideally, growers need to scout fields before seeding canola if they suspect a serious wireworm problem. No seed treatment or spray is registered for wireworm control in canola. Therefore, cereals with a wireworm seed treatment may be the better option for that field.

If a grower must seed canola in a field with high wireworm counts, a higher seeding rate will increase the odds of a good stand, given that the adult wireworm population will not increase in one season. Also seed shallow and into warm soils. Canola that gets off to a quick start and grows vigorously will be better able to tolerate wireworm feeding.

To scout, get down with a trowel and sifter and look for wireworms. Wireworms tend to migrate down to moisture, so may be deeper than cutworms. Bait balls are unlikely to work to scout for wireworms in these fields given the high volume of decomposing plant material. Note that cutworm numbers also tend to be high in pasture and hayland, but cutworms can be managed with surface applied insecticide. That’s another good reason to scout and find out what worms are present.

Bob Vernon at Agriculture and Agri-Food Canada’s Pacific Agri-Food Research Centre is collecting wireworm samples from the Prairies to see which species are present and where. Collected wireworms can be put into sealed containers with soil and shipped to his address.  He also needs all of the information (GPS ideally) as to exactly where the sample was collected, the crop
involved, the grower, the grower’s phone number and address, and date of collection. Click Bob’s name above to contact him for more information. His mailing address to send sample is 6947 Highway 7, PO Box 1000, Agassiz, B. C. V0M 1A0.