The microscopic, yield-robbing pests known as nematodes may be causing more damage to U.S. cornfields than experts previously thought.

But prudent field-testing, timely weed control and application of new crop-protection products on the market can reduce the risk of major damage, says Bayer CropScience agronomist Ray Knake.

“You’re never going to win the war against nematodes,” Knake told no-tillers during last January’s 19th annual National No-Tillage Conference in Cincinnati, Ohio. “All you can do is try to manage them to reduce your yield losses.”

What Kind Is It?

 Knake says no-tillers must know what types of nematodes are in their fields to better understand the damage they can do and how it occurs. In general, no-tillers could see a number of different nematodes in their fields, but the following are of concern:

• Lesion nematode: These are most common in the Midwest corn-growing region. They’re very small and feed from the inside of the root, leaving tiny holes behind that may allow diseases to take hold and weaken the plant

  “The damage they can cause can lead to a 30% yield loss, and there may only be one aboveground symptom,” Knake says.

• Needle nematode: Due to their larger size, they’re often restricted to sandy soils, but they can cause injury to corn plants at any population density. They can do serious damage to the root itself, resulting in a 10% to 75% yield loss

  Knake says the population threshold that is considered a risk for yield losses in corn can vary…