Unveiling Root-knot Nematodes and the Role of Suppressive Soils in Vegetable Production

Plant-parasitic nematodes (PPN) pose a hidden threat to vegetable production, with root-knot nematodes being among the most damaging soil-borne pests. These nematodes affect a wide range of crops and have caused significant yield reductions in Indiana, impacting both large-scale conventional vegetable production and small-scale diversified farms, particularly in high tunnel production. Despite their potential to cause severe yield loss, some soils in Indiana have been found to suppress the buildup of root-knot nematodes.

What symptoms you might see:

Root-knot nematodes cause swellings, known as galls, on the roots. These galled roots are less effective at taking up water and nutrients, which leads to unhealthy plants.  Affected plants often exhibit aboveground symptoms resembling nutrient deficiencies, including stunted growth, yellowing leaves, and reduced vigor.

galled-root-by-nematode-infection.png

Indiana vegetable growers:

If you are interested in learning more about your soils, evaluating the risk of plant-parasitic nematodes in soil, and determining whether your soil is conducive or suppressive to root-knot nematodes, consider participating in this project led by the Purdue Nematology Lab. Our primary focus will be on

  • Certified organic, or transitioning to organic vegetable farms or those managed using organic practices
  • Vegetable farms that are suspected of experiencing root-knot nematode damage

Our team will arrange a visit to your farm to collect soil samples and gain insights into your soil management practices. Following the visit, we will provide you with a comprehensive report that includes detailed soil test results. This report will cover plant-parasitic nematode populations, potential soil suppressiveness, soil texture, organic matter content, and basic chemical and biological information.

If you are interested in participating this project or want to learn more about it, please contact

Dr. Wenjing Guan at guan40@purdue.edu /352-870-4696 (text prefer)

Dr. Lei Zhang at leizhang@purdue.edu / 765-494-1933

This project is financially supported by the USDA-NIFA Organic Transitions Program (ORG) [Grant no. 2024-51106-43054] and North Central SARE Research and Education Grant [Project Number LNC24-511].