Columbia Root-Knot Nematode

Typical external symptoms

General Information:

Nematode species: Meloidogyne chitwoodi (Columbia root-knot nematode), Meloidogyne hapla (northern root-knot nematode).

Biology and Life History:

These plant-parasitic nematodes have complex life cycles (see above) involving a mobile stage that invades plant roots and tubers, and sedentary stages embedded in plant tissue. Root-knot nematodes overwinter easily throughout the Northwest. Most live in the top two feet of soil, but sometimes they are found up to 6 feet deep.


Both northern- and Columbia root-knot nematode are widely distributed across the western states of the U.S. In the Northwest, Columbia root-knot nematode is most prevalent and damaging.


  1. Synthetic nematicides and soil fumigants are important and often necessary tools for nematode management in potatoes due to very low market tolerance for damage.
  2. Crop rotation strongly affects nematode population size in the field. Each nematode species has a different host range. Therefore, sample and identify nematodes from each field and design crop rotations that will limit population growth.
  3. Various green manure and cover crops can reduce nematode populations.
  4. Prevention is also important: plant only certified seed tubers, and avoid moving soil from infested to uninfested fields.
  5. Weed management between potato crops is also critical. Some weeds are good hosts for root-knot nematodes.

Further Reading:

Pacific Northwest Pest Management Handbooks

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