Watch for Signs of Wireworms at Harvest

September 20, 2018

Wireworms are one of the most challenging insects on the Prairies. That’s why you should determine whether the yield-robbing pests are present in the fields you’re planning to seed to malting barley next spring.

Wireworms (larvae stage) exist entirely underground and can be difficult to diagnose. They prefer to feed on cereals, but can also cause significant damage to corn, sugar beets, potatoes, sunflowers, lentils and other crops.

At this time of year, the larvae have finished feeding and are moving down into the soil profile; they’ll return in spring when warmer soil temperatures and germinating seeds draw them to the surface. The best way to confirm your risk is by setting bait traps prior to seeding, but there are some things to watch for this fall that could give you a heads up that wireworms are present in your field.

Thin stands, weed flushes

“If you notice a dip in the yield monitor when harvesting, one of the causes could be wireworm damage,” says Ted Labun, Seedcare Technical Lead with Syngenta. He says signs from the combine include patches of thin stands or no stands at all.

Wireworm larvae feed on germinating seeds, roots and young seedlings, killing plants directly as well as creating wounds that are ideal for disease establishment. Poor stands can be mistaken for a seeder miss, poor seed-to-soil contact, dry growing conditions, cutworm damage or herbicide carryover.

Labun adds that seeing second flushes of weeds at harvest could be another signal of wireworm infestation. “Weed escapes could be a sign of wireworm presence as feeding damage leads to thin stands that can’t compete with second flushes of weeds.”

These telltale signs are worth noting this fall in order to help you put a plan of action in place for next season.

Best management practices for wireworm control

According to Labun, some tips to mitigate wireworm damage include the use of a seed treatment as your first line of defence. There are also agronomic practices that can help.

“If you have significant issues in your field, planting a little bit heavier should compensate for the seedling loss you may have,” says Labun. “A shallower seeding depth and seeding into warmer soil will also help your crop come out of the ground a little faster and set its root system.”

Syngenta has conducted several surveys to detect the presence of click beetles (the adult form of wireworms) and wireworms across the Prairies. Check out this map to see where the pest is most prevalent.


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