Potentially Damaging Corn Nematode Populations Found in the Corn Belt and Southeastern U.S.

• This study found over 50% of corn fields sampled throughout the Corn Belt and Southeast had medium to high levels of nematode pressure.
• Nematodes were widely distributed through all sample areas and not confined only to sandy soils.
• The most prevalent species of nematodes varied by region and included lance nematode in the Eastern Corn Belt, stubby root and dagger in the Western Corn Belt, dagger and root-knot in Wisconsin, and root-knot and stubby root in the Southeast.

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.

• 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 and 2020, Pioneer agronomists sampled corn fields in several regions to assess nematode population levels and the range of species present:
  • Eastern Corn Belt: Illinois and Western Kentucky
  • Western Corn Belt: Iowa, Nebraska, Kansas, Colorado, Missouri, and Texas
  • Wisconsin
  • Southeast: Alabama, Florida, and Georgia

• A total of 748 corn fields were sampled for nematode populations in 2019 and 2020.
• 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).
• 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.

• Nearly all fields sampled (93%) had corn nematode species present at some level (Figure 1).
• Medium and high population levels were prevalent across all regions in the study. 

Figure 1. Corn nematode pressure at sites sampled in 2019 and 2020.

Figure 2. Corn nematode pressure level of fields sampled in 2019-2020.

Figure 3. Corn field sampled in 2019-2020 with high population levels of major corn nematode species, by region.

Figure 4. Corn nematode pressure level of fields planted to first year corn compared to fields in second year corn.

• The Western Corn Belt and Wisconsin had the highest percentage of fields with medium and high corn nematode pressure; however, potentially damaging levels of corn nematodes were widespread in all regions (Figure 2).
• Lance, stubby root, and spiral nematodes were the species most commonly found at levels above the high population indicator (Figure 3).
• Over 10% of fields had more than two species of nematodes above the high population indicator level.
• Sting and needle nematodes, which are potentially damaging at any population level, were found in all regions but less commonly in the Eastern Corn Belt (Figure 3).
• Root knot nematode, which can also affect soybean production, was found most often in the Southeast and Western Corn Belt (Figure 3).
• Average corn nematode pressure tended to be higher in corn following corn. 41% of first year corn fields had moderate to high levels of nematodes compared to 53% of second year corn fields (Figure 4).

• 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 are available with two seed treatment options 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 more than 80 days in the upper, middle, and lower root zones.
  • Poncho^® 1250 + VOTiVO^® insecticide provides a biological mode of action to protect corn seedlings and roots against nematodes.
  • Poncho 1250 + VOTiVO insecticide contains a unique strain of bacteria that lives and grows with young corn roots, creating a living barrier that helps protect corn seedlings and roots against nematodes.