Wireworms no joy for wheat producers

The click beetles have a catchy name and in the adult stage they represent no threat to cereal crops. Unfortunately this beetle’s larval stage—wireworms—can crimp a wheat producer’s profits if he has an infestation.

The mature larvae range from a half- to 1-inch long, according to the Kansas State University Extension entomology department. The larvae are slender and shiny, yellow to brown, with six slender, short legs and they feast on seeds.

Ruhiyyih Dyrdahl-Young, technical field representative for BASF’s Northern Great Plains Seed Treatment division, Fargo, North Dakota, said wireworms are more likely to thrive in tight cereal-on-cereal rotations. Most infestations are in the northern Plains but a growing number of reports are being filed in the southern Plains, which was one reason for her willingness to address concerns of growers during the recent Sorghum U/Wheat U virtual event sponsored by High Plains Journal.

“Wireworms can do some pretty serious damage,” Dyrdahl-Young said. “A producer can see a 50% reduction in production. Stand loss is the damage early, but then the costs later in the season occur during the time of tillering.”

A winter wheat grower needs to check his crop before frost hits in the fall and be vigilant in the spring once dormancy breaks and the plant heads to the tillering stage, she said. Inconsistent maturity can also be a sign of wireworm infestation.

The shelf life makes the wireworms a formidable pest. The larvae have been known to live five to seven years in the ground, she said, which is opposite of many aphids and pests that are generally a one-time nemesis for a wheat grower, she said. Plus, the wireworm has an ability to adapt to changing soil conditions.

“The population can really build up and do some serious damage,” Dyrdahl-Young said.

Another problem is treatments today. Mostly seed-applied neonicotinoids, can only help repel the pest but they do not lower the population or stop the deterioration of the crop once it is infested.

Click beetles like cover and it is a reminder that as growers continue to expand no-till acres and explore cover crops they will need to keep in mind that can foster a breeding ground for a tough pest, Dyrdahl-Young said. Fields once enrolled in the Conservation Reserve Program, or in pasture or are located near a wheat field can become a favorite habitat for the click beetle.

Adult beetles like to lay eggs in pastures or something that has ground cover, she said, adding no-till acres can provide a fertile ground for the beetle. Continuous crop production also is where the wireworm has an opportunity to succeed.

The current class of insecticides and fungicides she has monitored has mixed results. BASF is unveiling a new product in 2021 that she believes can help growers yet she stressed the importance of producers scouting their fields.

Her company, BASF in 2021 is introducing Teraxxa seed treatment insecticide which is showing great promise in tests in killing wireworms.

“It will be a game changer,” she said, adding that is still important for growers to be vigilant in their scouting.

A simple check

Dyrdahl-Young offered a cost-effective way to check for an infestation.

“Take a seed corn and wheat seed and put it in a cup then use a woman’s hosiery and fill it up. Soak it overnight in water and that will cause the seeds to quickly germinate. Then bury it out in the field and the wireworms can sense the food and feed on it. You can then pull it out of the ground and count the wireworms.”

Dave Bergmeier can be reached at 620-227-1822 or [email protected].