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Root rot or a soil problem: look at the root before you fertilise

A brown bald tip from acid is not the same as a wet rot.

Same crop again
Speed
  1. Patch death: look at the root first.
  2. Black rot, knots, pinched stem bases are not the thin white roots of hunger.
  3. Nutrient shortage is a sheet by leaf position; root rot is patches, roots first.
  4. Drought is dry soil, the whole field wilting at noon; root rot is often still wet.
  5. Don’t chase patch death with fertiliser; don’t drench a rotten root with strong feed.
  6. This page does not hand out a bag: Stop the feed first and look at the roots. Sort it first, then open the matching guide
  7. Name what you see before you feed.
  8. If leaves, roots and the surface disagree, stop.

What you see in the field

Patch death: look at the root first. Black rot, knots, pinched stem bases are not the thin white roots of hunger.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 “Nutrient-shortage yellow leaves”

    Nutrient shortage is a sheet by leaf position; root rot is patches, roots first.

  • Looks like “Drought”

    Drought is dry soil, the whole field wilting at noon; root rot is often still wet.

Do this / don’t do that

  1. 1Patch death: look at the root first. Black rot, knots, pinched stem bases are not the thin white roots of hunger.
  2. 2Pull a bad plant and a good one. Patch plus brown roots go to plant protection. Uniform yellow goes to nutrient or wet. No pesticide recipes here.
  3. 3Don’t chase patch death with fertiliser. Use the 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 patch death with fertiliser; don’t drench a rotten root with strong feed.

Rate range

This page does not hand out a bag

Stop the feed first and look at the roots

Sort it first, then open the matching guide.

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

Root colour

The first cut

White / brown / smelly.

EC

Salt also hurts roots

Look harder in a house.

When you see Patch death: look at the root first. Black rot, test. Take soil from the bad patch and from a greener neighbour, separately.

Lesson video

2026-03-14 · 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