There are over 40 species of corn nematodes affecting U.S. agriculture, including needle, root-lesion, dagger, lance, and stubby-root nematodes. These organisms pierce root cells with their mouthparts and suck out their contents, weakening the root system. Damage worsens under dry conditions, when plants are already under water and nutrient stress.

Many growers miss infestations because nematode damage is easily misdiagnosed. Symptoms like stunting, yellowing, and uneven patches in the field can resemble nutrient deficiencies or compaction issues. Also, plants may look healthy above ground while their roots are severely compromised.

Economic Impact and Yield Reduction

The economic toll of nematodes is substantial. An estimated 56 million bushels are lost annually in the U.S., affecting both farm income and broader commodity markets. Nematodes interfere with water and nutrient uptake, reduce vigor, and enable soilborne fungi and bacteria to infect. These effects accumulate, harming uniformity and grain quality.

How to Detect the Underground Threat

Early detection is critical, but nematodes can't be diagnosed just by field scouting. Proper soil sampling is a must. Experts recommend collecting over a dozen 6-inch-deep soil cores across the affected area. Take samples pre-plant or post-harvest, and send them to a specialized nematology lab for species identification and population levels.

Farmers should repeat testing every two to three years, especially if yields have dropped or unexplained stunting appears. Knowing which nematode species are present allows for more effective management strategies.

Management and Control Strategies

With fewer traditional nematicides available, integrated pest management is essential. Strategies include:

Seed Treatments: Many modern corn hybrids come with nematode-protective seed treatments, effective for low to moderate populations.

Crop Rotation and Cover Crops: Rotating with non-host crops or using specific cover crops can disrupt the nematode life cycle. Effectiveness depends on the species, as some have wide host ranges.

Soil Health: Good fertility and proper irrigation encourage robust root growth, making plants more resistant.

Weed Control: Many nematodes survive on grasses, so strong weed management is essential.

Operational Sanitation: Avoid moving infested soil between fields. Clean equipment and handle infested fields last to prevent spread.

With changing climates and rising pest pressure, nematodes will be an increasing concern. As the farm bill and USDA programs evolve, producers should tap into technical support and funding to promote pest control and soil health.

Proactive management backed by lab diagnostics and precision ag tools can mitigate the threat from corn nematodes, ensuring stronger roots, healthier crops, and more reliable yields.