Powdery mildew on pepper
Usually caused by Leveillula taurica, which grows inside the leaf — so the bloom shows up mainly underneath, while the upper surface develops pale, yellowing patches. Common in tunnels in warm summers.
Symptom photos
Symptoms
- Pale, yellowing patches on the upper leaf surface
- A greyish-white, powdery bloom on the leaf underside
- Leaf edges curling upwards
- Patches browning and leaves dropping early
- Symptoms first on the older leaves lower down the plant
What it does to the crop
- Leaf loss and sunscald on the exposed fruit
- Growth checked and a smaller crop
- Smaller, poorly colored fruit
- Plants weakened before picking is finished
What encourages it
- High temperature, 25-30°C in the tunnel
- Big swings in humidity between day and night
- Water stress and uneven irrigation
- Crowded planting and poor air circulation
Prevention
- Ventilate and keep humidity steady
- Irrigate evenly with no dry spells
- Remove the first affected leaves from the base of the plants
- Keep to the recommended spacing and take out crowding leaves
- Grow less susceptible varieties
⚠️ Before you reach for a spray
This atlas is informational and still growing — different diseases can look almost identical. Confirm the diagnosis and read the product label before applying any plant protection product. If you are unsure, ask your local extension or advisory service.
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