Nutrient Deficiency (Chlorosis)
Chlorosis is yellowing from a lack of chlorophyll, usually because the tree is short of nutrients — either because it hasn't been fed, because the soil…
Nutrient Deficiency (Chlorosis) at a glance
| Also known as | Chlorosis, yellowing, nitrogen/iron deficiency |
|---|---|
| Affected parts | Leaves |
| Most at risk | Trees overdue for feeding/repotting; acid-lovers in alkaline water (azalea, gardenia, camellia) |
| Main cause | Not enough nutrients, or roots unable to take them up (pH/old soil) |
| Severity | Mild to moderate; weakens the tree if prolonged |
| Reversible? | Yes — corrects with feeding / repotting / pH fix |
What to look for
- Leaves: Nitrogen shortage: uniform pale-green to yellow, starting on older/lower leaves, with weak growth. Iron/manganese shortage: yellowing between the veins while the veins stay green (interveinal chlorosis), on the youngest leaves first. Potassium: yellow/scorched leaf edges.
- Soil: Normal moisture; often old, compacted, or long-unfertilised soil.
- Roots: Healthy and firm (which distinguishes it from rot).
- Whole tree: Overall pale, lacklustre foliage and reduced vigor.
Overview
Chlorosis is yellowing from a lack of chlorophyll, usually because the tree is short of nutrients — either because it hasn't been fed, because the soil is exhausted/broken down, or because the roots can't absorb what is there (often an iron lock-out when the water/soil is too alkaline). The pattern of yellowing points to the cause.
Causes
Skipped feeding; old/exhausted soil overdue for repotting; alkaline water or soil locking out iron (especially for acid-loving species); root damage or rot reducing uptake; and very cold or waterlogged soil temporarily stopping uptake.
Commonly confused with
Overwatering/root rot also yellow leaves — but the soil is wet and roots are poor; here roots are healthy and soil moisture normal. Natural autumn colour is seasonal and uniform. Spider-mite stippling looks speckled/bronze, not the smooth yellowing of chlorosis.
Which species are affected
All species if underfed; acid-loving species (azalea, gardenia, camellia, blueberry-relatives) commonly go iron-chlorotic in hard/alkaline water; vigorous, hungry species (mulberry, water jasmine, privet) yellow quickly if underfed.
Treatment
Resume a balanced feeding program; if the soil is old/compacted, repot into fresh mix. For interveinal (iron) chlorosis, use an iron/sequestered-iron feed and acidify with rainwater or an ericaceous regime for acid-lovers. Correct any underlying root or watering problem first — feeding won't help if roots are rotting.
Prevention
Feed regularly through the growing season; repot on schedule to refresh soil; use appropriate (often rain/soft) water for acid-lovers; keep roots healthy.