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Root-knot nematodes: galls on the root, extra fertiliser won’t grow it

Look at the root. Beads and knots are not fertiliser burn.

Same crop again
Speed
  1. Beads and galls on roots; extra fertiliser won’t grow.
  2. Those pearls are not rhizobia.
  3. Legume nodules that are pink fix nitrogen; nematode knots sit on vegetable fine roots and are not pink inside.
  4. A shortage rarely kills in patches plus root galls.
  5. Don’t chase it with fertiliser; don’t drench galled roots with strong feed.
  6. Rotation: Change the family. Years follow local advice. Steadier than spraying again and again
  7. Name what you see before you feed.
  8. If leaves, roots and the surface disagree, stop.

What you see in the field

Beads and galls on roots; extra fertiliser won’t grow. Those pearls are not rhizobia. Patch wilt.Patchy dead plants: look at the roots first — knots, brown rot, stained pipes — not the thin white roots of hunger. A rotated neighbour that still looks well is the contrast that counts.

A sketch. Do not fertilise from the picture alone.

Tap to enlarge. The caption says what to photograph. Missing field photos are marked as to-be-added.

Why it looks like this

The field looks like this because the root cannot take water or nutrients the usual way. Fix the soil condition first — drainage, salt, acidity, compaction or a salt of fertiliser — then a thin feed. Rates live in the range on this page; confirm with a local station and the label.

Easy to mix up

  • Looks like “Rhizobium”

    Legume nodules that are pink fix nitrogen; nematode knots sit on vegetable fine roots and are not pink inside.

  • Looks like “Even yellow from shortage”

    A shortage rarely kills in patches plus root galls.

Do this / don’t do that

  1. 1Compare the worst plants with a neighbour ridge. Photograph whole plant, close-up and soil surface before you add fertiliser.
  2. 2Match roots, leaves and the soil surface to this guide. If they do not line up, do not copy a bag count.
  3. 3Use the rate range on this page only as a range. Confirm with a local station and the product label.

Don’t do this first

  • Don’t chase it with fertiliser; don’t drench galled roots with strong feed.

Rate range

Rotation

Change the family. Years follow local advice

Steadier than spraying again and again.

Clear the trash

Take it out with the root

Leaving it in the field is leaving inoculum.

These are ranges. Confirm with your local extension station and the product label.

Root knots or not

Whether this is the path

Galls: think nematode first.

When you see Beads and galls on roots; extra fertiliser won’t grow. Those pearls are not rhizobia. Patch wilt, test. If the leaf and the soil disagree, test before you pour.

Lesson video

2026-03-20 · Li Zeyu · For learning. Serious damage: local agronomist or a soil test.

For learning only. Fertiliser and pesticide decisions need a local agronomist and a soil test.

Not sure? Photograph the field to identify the problem