Root-Lesion Nematode
Symptoms:
- 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.