Lesion Nematode
Pratylenchus penetrans, P. vulnus, P. neglectus
Overview
Lesion nematodes (Pratylenchus species) are migratory endoparasites that tunnel through root cortex tissue of a very wide host range, including vegetables, fruits, grains, and ornamentals. They move in and out of roots, leaving brown lesions that invite secondary fungi and bacteria. Populations build in continuous cropping systems and sandy soils. Damage is often underestimated because the nematodes are microscopic and above-ground symptoms look like general poor root health or drought stress.
Symptoms
Roots show dark, elongated lesions, stubby growth, and reduced feeder roots. Plants wilt easily on warm days, grow slowly, and may yellow. Yield drops without a dramatic single pathogen lesion on leaves. In mixed infections, lesion nematodes worsen fungal root rots. Damage often appears in sandy spots or beds that have grown the same crop family repeatedly. Digging plants reveals brown root scarring rather than the knots typical of root-knot nematodes.
Environmental Conditions
Variable
Prevention
Diversify rotations and include cover crops rather than leaving beds in the same vegetable family. Bring in only clean transplants and avoid sharing unwashed root balls between gardens. Improve irrigation uniformity so plants are not chronically drought-stressed on top of root feeding. Test soil for nematodes if patchy decline persists despite good fertility. Mulch and organic matter help root resilience even when some nematodes remain.
Management
Rotate with poorer hosts when known for your Pratylenchus species, though many have broad ranges. Build soil organic matter with finished compost and diverse cover crops to favor nematode-antagonistic fungi and microbes. Remove heavily damaged root systems from beds when practical. Avoid planting highly susceptible crops back-to-back in sandy soils. Solarization in hot climates can reduce populations in the upper soil. Commercial nematicides are generally not a first choice for ecological gardens.