⚠ ModeratePale patches on top with olive-green mould underneath — leaf mold, a humidity and ventilation problem above all else.
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Fungal
Leaf Mold on Tomato Plants
Commonly affects: Solanum lycopersicum (Tomato)
Pale yellow patches appear on the upper leaf surface, with an olive-green to grey-brown velvety mould growing directly beneath them on the underside. Common in greenhouse and high-tunnel tomatoes with limited airflow.
Potential Causes
- 1Cladosporium fulvum fungus, favoured by high humidity (above 85%) and poor ventilation
- 2Greenhouse or high-tunnel growing conditions that trap humid air around foliage
- 3Overhead watering keeping leaf surfaces wet for extended periods
Solution Steps
- 1Remove and destroy affected leaves, working from the bottom of the plant up.
- 2Maximise ventilation — open vents, run fans, and space plants for airflow.
- 3Water at the base only, and avoid watering late in the day when foliage can't dry before nightfall.
- 4Apply a chlorothalonil or copper-based fungicide if the problem persists despite ventilation improvements.
Prevention Tip
Leaf mold is almost entirely a humidity and airflow problem — greenhouse growers should prioritise ventilation over any fungicide programme.
