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.