It sounds like science fiction, but it’s science fact. Wireworms have been infiltrating fields for decades, causing unwanted damage to crops. It’s a tough pest to manage, as they eat almost anything in the soil: decomposing plant material, seeds and germinating seedlings.
Wireworms, the larval stage of click beetles, have been on the radar of growers and crop scientists dating back to the early 20th century. However, the development of effective organochlorine insecticides pushed the focus on these pests to the back burner. Because the products were so successful in managing wireworms, research dwindled for years.
“Now, researchers are starting to see more and more wireworms infesting fields. Even neonicotinoid insecticides can’t hold them back — they’ll eat right through the seed coating,” said Jim Vandecoevering, BASF Tech Service Manager for the Western Region.
The problem is compounded when adult click beetles from surrounding permanent habitats — grassy ditches, pasture and undisturbed field borders — start to invade the vulnerable crop fields. The wireworm population then has the chance to explode underground at an exponential rate.
Once wireworms make their way into a field and reach significant populations, they pretty much move in permanently, and you’re likely to have them year after year. You may see symptoms such as:
- Stunting damage: Wireworms will chew into the stems of the plants and fruits that touch the ground
- Wilting flag leaf
- Patchy, bare areas on the field; wireworms also like irrigated soil and often accumulate in the drip line of an irrigated pivot
“Since the wireworm has such broad eating habits, crop rotation and cover crops are not always the most effective tools to combat them,” said Vandecoevering. “The best way to minimize the pest’s damage is to scout the field in early spring.”
You can scout before or after crop emergence to investigate if the field is damaged by wireworms. Heading to a patchy field and digging up roots will often reveal the pests. Other means include planting bait or a stocking trap into the soil to attract them.
If wireworms are discovered in the soil, you should collect a few, store them in alcohol and send them to a local entomologist to determine their species. Once the species is determined, it is easier to pick the most effective seed treatment for the job. And in this science fact story, that’s a happy ending.