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Fungal
Sooty Mould on Lemon Tree
Commonly affects: Citrus limon (Lemon Tree)
A black, sooty coating develops on leaf surfaces, usually following an existing infestation of a honeydew-producing pest like scale, aphids, or whiteflies.
Potential Causes
- 1Sooty mould growing on the sugary honeydew excreted by sap-sucking pests, rather than infecting the plant tissue directly
- 2An underlying, possibly unnoticed, pest infestation being the root cause
- 3The mould itself being largely cosmetic but blocking light from reaching the leaf surface if extensive
Solution Steps
- 1Identify and treat the underlying pest infestation first, since the mould won't resolve until the honeydew source is eliminated
- 2Wipe away sooty mould with a damp cloth once pests are controlled
- 3Improve air circulation to help prevent mould from developing on any residual honeydew
- 4Monitor closely for the pest's return over the following weeks
Prevention Tip
Sooty mould is always a secondary symptom on citrus â controlling the underlying pest, not just cleaning the mould, is what resolves the problem.
