Corn Nematode Populations in the Corn Belt

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Agronomy Research Update
Written by Dr. Mary Gumz, PhD, Pioneer Agronomy Manager

Key Findings

  • This study found 35% of corn fields sampled throughout the U.S. Corn Belt had medium to high levels of nematode pressure.
  • Corn nematodes were present in 99% of the soil samples collected in 2022.
  • Nematodes were widely distributed through all sample areas and not confined only to sandy soils.

Rationale and Objectives

  • Corn nematodes can cause significant yield loss by damaging corn roots, which impairs water and nutrient uptake and creates entry points for pathogens.
  • In 2019, 2020, 2021, and 2022, Pioneer agronomists, territory managers, and sales professionals sampled corn fields across the U.S. Corn Belt to assess nematode population levels and the range of species present.
  • Over 3,100 samples were collected from fields in 19 states: Texas, Oklahoma, Colorado, Kansas, Nebraska, North Dakota, South Dakota, Minnesota, Iowa, Missouri, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, New York, Maryland, and Delaware.

    Stunted growth of the corn plant on the left due to corn nematode pressure.

    Stunted growth of the corn plant on the left due to corn nematode pressure. Above ground symptoms of nematodes are often nondescript and resemble low fertility, weather stress, or insect and disease pressure.

How We Investigated Nematode Levels

  • A total of 3,164 corn fields were sampled for nematode populations from 2019 to 2022.
  • Soil samples were taken at approximately the V6 growth stage.
  • Soil samples were taken from both within and between the row and contained corn root tissue.
  • Samples were submitted to a nematode testing service and analyzed using a sugar-floatation method and a 500 mesh sieve.

Nematode Pressure Levels

  • Scientists at Corteva Agriscience have developed high population indicators for major corn nematode species as a relative measure of population levels (Table 1).
  • The Corteva Agriscience nematode rating is based on a combination of thresholds from seven labs throughout the Corn Belt. It rates the potential for yield damage due to nematodes based on the population and species of nematodes present.
  • Nematode pressure in a field was classified based on the high population indicator level for each species:
    • High: Above indicator level for one or more species.
    • Medium: Above 50% indicator level for one or more species.
    • Low: Less than 50% indicator level for all species.

      Table 1. Corteva Agriscience population level indicators for major corn nematode species.

      Species High Moderate Low
        -- nematodes / 100cc soil --
      Sting 1 NA NA
      Needle 1 NA NA
      Lance 50 25-49 1-24
      Stubby-Root 50 25-49 1-24
      Root Knot 50 25-49 1-24
      Dagger 100 50-99 1-49
      Lesion 150 75-149 1-74
      Ring 200 100-199 1-99
      Stunt 300 150-299 1-149
      Spiral 500 250-499 1-249

Results: Potentially Damaging Nematode Levels

  • Nearly all fields sampled had corn nematode species present at some level (Figure 1).
  • 35% of corn fields sampled had medium to high levels of nematode pressure (Figure 2).
  • Medium and high population levels were found across all regions in the study.
  • High nematode population levels were most prevalent in the western Corn Belt states – Nebraska, Kansas, Colorado, and Texas.

Map - Corn nematode pressure at sites sampled in 2019, 2020, 2021, and 2022.

Figure 1. Corn nematode pressure at sites sampled in 2019, 2020, 2021, and 2022. Click here or on the image above for a larger view.

Corn nematode pressure at sites sampled in 2022.

Figure 2. Corn nematode pressure at sites sampled in 2022.

Video: Plant Parasitic Nematodes

Managing Corn Nematodes

  • Results of this study showed that potentially damaging levels of corn nematode populations are prevalent throughout corn production areas in the U.S.
  • If damaging levels of corn nematodes are found, implementing control measures such as rotation, sanitation or use of nematicide seed treatments should be considered.
  • Nematode species vary in their host range, so rotation can be effective for reducing populations of some, but not all, corn nematode species.
  • Pioneer® brand corn products come with Lumialza™ nematicide seed treatment for nematode control:
    • Lumialza nematicide seed treatment is a biological product that contains the active ingredient Bacillus amyloliquefaciens – Strain PTA-4838 and has activity against all primary corn nematode species.
    • National trials have shown yield improvements of 3.7 bu/acre under low pressure and up to 9 bu/acre in high pressure fields.
    • Research has shown that nematode protection lasts for over 80 days in the upper, middle, and lower root zones.


Protect Your Roots From Nematodes

Lumialza™ nematicide seed treatment has shown yield increases of 3.7 bu/A under low nematode pressure and up to 9 bu/A in heavy pressure in national trials.

Protect Your Seed

Logo - Lumialza nematicide seed treatment

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. 2019-2022 data are based on average of all comparisons made in 3164 locations through November 1, 2022. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Lumialza® may not be registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions. Performance data is based on 10-state broad-acre head-to-head strip trial comparing Lumialza™ nematicide seed treatment vs. non-nematicide seed treatment utilizing the same insecticide and fungicide recipe in seed applied technology replicated and strip trial data. Yields ranged from 3 to 9 bu/acre depending on nematode species and population, in 184 low stress and 54 moderate to high stress locations. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary. Pioneer® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents. Individual results may vary.