By Quinton Cubbon, AAg, Crops Extension Specialist, North Battleford
May 2024
Have you ever noticed your wheat crop looks a little patchy in some areas with some yellowing and wilting? It could have been a seeding error or herbicide carryover; however, it could be a wireworm problem.
Wireworms are the larvae of click beetles. A click beetle is a small beetle that can be identified by the defensive clicking noise it makes when placed on their backs. There are thousands of these species around the world. With 182 species in the prairies, 11 of them are considered crop pests in Saskatchewan, with only two of these species are treated as major pests; the Hypnoidus bicolor and Selatosomus aeripennis destructor (Prairie grain wireworm). Wireworms are typically white to orange in colour and can range from two to 23 millimetres in length. Wireworms are most vulnerable when they first hatch, as they are prone to starvation, cannibalism and poor environmental conditions. After the first year, a wireworm develops the ability to move through the soil to find resources and becomes more stress resilient. It is known as the residential stage where they will remain for several years. In the spring, common wireworm damage includes hollowed out, or tunnelled seeds and stem shredding on cereal and pulse crops. The residential wireworms are the most damaging to wheat and pulses in the spring.
Early season scouting for wireworms, prior to seeding, can be used to determine the number of wireworms in a specific field. When the soil temperature has reached 10 degrees Celsius, before seeding, place a bait ball in the soil. These bait balls usually consist of oatmeal, honey, nuts and peanut butter wrapped in cheese cloth. They should be located throughout a field and return in two weeks; it is recommended that at least 20 are placed per quarter section. If there are one to two wireworms per trap, you may want to use a control option.
Control Options
The main and probably most widely used control option is an insecticidal seed treatment. There are a few products on the market that can offer some control against wireworms. Products that contain imidacloprid, broflanilide, chlorantraniliprole or thiamethoxam all offer early season control for wireworms. Crop rotation has some effectiveness with mustard and buckwheat showing the best results for control the following seasons. Increased seeding rate can help as having a higher plant stand allows some plants to be damaged while still maintaining the proper plants per square metre. Also, delaying seeding can result in cannibalism or starvation of the wireworms as the food source is limited.
For more information or if you have any questions about wireworms, please contact your local crops extension specialist or call the Agriculture Knowledge Centre at 1-866-457-2377.