When temperatures rise, so do wireworms

Best practices for managing a wireworm infestation

As temperatures rise and soil moisture increases, wireworms move upward toward the soil’s surface. Growers should be prepared for the resilient pests that eat almost anything: decomposing plant material, seeds and germinating seedlings. With active measures and pest management best practices, growers can make sure to limit the damage done by wireworms.

 

“Wireworms are the larval stage of click beetles and live entirely below ground for two to six years,” said Mitch Stamm, BASF Biology Project Leader. “Once wireworms make their way into a field and reach a significant population, growers are likely to have them year after year.”

 

Since the wireworm has such broad eating habits, crop rotation and cover crops are not the most effective tools to combat them. The best way to minimize the pest’s damage is to scout the field in the early spring. If wireworms are present in the field, growers will see:

  • Stunting damage: Wireworms will chew into 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

A grower can scout before or after crop emergence to determine why a field may be damaged. Heading to a patchy field and digging up roots will often reveal the wireworms. Other means include planting bait or a stocking trap into the soil to attract the pests. Use a stocking stuffed with seeds, soak it in water overnight and plant it into the soil for one to two weeks.

 

Once a field is determined to have an infestation of wireworms, there are several steps growers can take to combat them.

 

The one crop growers can rotate
Even though rotating crops is not the most effective solution for combating this particular pest, there is one crop that is less preferable to wireworms: alfalfa. Alfalfa can tolerate the wireworms better and is a less desirable food source to the insects.

 

After a five- to seven-year rotation, using alfalfa might reduce the number of larvae in the soil, but it’s not likely to get rid of all the wireworms.

 

Put the seed in late
Wireworms rise to the surface of the soil at the beginning of spring, when soils begin to warm. This is the same time growers will plant their seed. Growers could consider planting the wireworm-infested soil last, in late spring, when the soil temperature gets too high and wireworms begin to retreat back into deeper soil.

 

“You don’t want the crop sitting in the soil for a long period of time, as seed or small seedlings become more susceptible to damage,” said Stamm. “If you plant your crop a little later, it’s growing quicker and has a better chance of growing out of the wireworm damage.”

 

Seed treatments
The main wireworm management recommendation is to protect crops with insecticidal seed treatments. If wireworms are discovered in the soil, collect a few and store them in alcohol. Send them to a local entomologist to determine the species. Once the species is determined, it is easier to pick the most effective seed treatment for the job.

 

With scouting, seed treatments and natural management practices, such as rotating in alfalfa or planting later in the season, growers will have a better chance to combat the resilient wireworm. To learn more about BASF’s seed solutions, please visit www.agriculture.basf.com.

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