Pests & diseases › Root-Knot Nematodes
Root-Knot Nematodes
Microscopic soil-dwelling worms that cause gnarled lumpy roots. Plants stunted and yellowing despite good care.
Symptoms
- Stunted plants that don't respond to water or feed
- Lumpy galled roots (different from nitrogen-fixing nodules — galls are part of the root itself)
- Yellowing foliage, wilting in heat
- Worst in sandy soils and warm climates
Lifecycle
Persists in soil for years. Worst in sandy southern soils.
What to do
- No curative treatment
- Solarize soil in summer (clear plastic for 6+ weeks in full sun)
- Grow marigolds (French Tagetes patula) as cover crop — proven nematicide for following year
If it's bad
- No effective home-garden nematicides
Stop it coming back
- Resistant varieties: VFN-coded tomatoes (the N is nematode-resistant), Mississippi Silver cowpeas
- Long rotations with grasses (oats, rye, sorghum-sudangrass)
- Add organic matter generously — promotes nematode-eating microbes
- Marigold cover crops
Crops it goes for
Plan the plot, track every sowing, cook the harvest
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.