Plant-parasitic nematodes
Microscopic roundworms that feed on roots, causing knots (Meloidogyne), cysts (Heterodera), or lesions. Above-ground symptoms mimic nutrient deficiency or drought.
Soil sampling
Collect soil from root zone at 15–30 cm depth. Send to diagnostic lab for extraction and counting. Population thresholds vary by crop.
Other soil-borne threats
- Phytophthora — oomycete causing root rot and sudden wilt.
- Rhizoctonia — damping-off in seedlings.
- Verticillium — vascular wilt with internal stem discoloration.
Management
Soil solarization, resistant varieties, long rotations, and clean transplant production reduce soil pathogen loads.