Root-Lesion Nematode


  • Plants infected with root-lesion nematodes do not typically have clear diagnostic symptoms.
  • Root-lesion nematodes may kill seedlings and impair stand establishment.
  • Older, infected plants may be stunted and appear in scattered patches in a field. Areas with disease may be weedy and have reduced stand density and yield.
  • Infected plants may have dark, brown-black lesions on the surface of roots. Fine, fibrous roots and Rhizobia nodules may be absent due to nematode feeding, resulting in impaired nutrient uptake.

Pathogen Involved:

  • Pratylenchus penetrans and other Pratylenchus spp..
  • These nematodes can infect many different crops and weeds
  • Root-lesion nematode infections may increase susceptibility to other root diseases such as Bacterial wilt and Fusarium wilt, and may increase the severity of winter or drought damage

Time of Occurrence:

  • All season

Conditions Favoring Disease:

  • Damage to alfalfa is most common in fields with sandy soils that can enhance movement of nematodes

Disease Management:

  • Very little resistance is available for root-lesion nematodes in alfalfa cultivars.
  • Crop rotation is of limited value as a control measure
  • Infested fields will generally remain infested indefinitely because the root-lesion nematode has many crop and weed hosts.
  • Seed and harvest infested fields last, and clean equipment between fields to avoid spreading nematodes in infested soils to new fields.