🍅 Tomato How hard it is to control: ★★☆☆☆ 2/5

Powdery mildew on tomato

Significant problem in greenhouse crops in recent years. Development cycle approx. 5-7 days. Optimal development at 50-70% humidity and 20-25°C. Does not require leaf wetness.

Symptom photos

Powdery mildew — Leaves densely covered in white, powdery growth — Leaves densely covered in white, powdery growth Photo: Schlaghecken Josef, licence CC BY 4.0

Powdery mildew — Whole plant — mildew on the leaves around the set fruits — Whole plant — mildew on the leaves around the set fruits Photo: Schlaghecken Josef, licence CC BY 4.0

Powdery mildew — Leaves side by side — one healthy, one covered in white growth — Leaves side by side — one healthy, one covered in white growth Photo: Schlaghecken Josef, licence CC BY 4.0

Powdery mildew — Stems — greyish-white growth covering the shoots — Stems — greyish-white growth covering the shoots Photo: Nieznany, licence CC BY-SA 3.0

Symptoms

Small round spots on upper leaf surface
White powdery mycelial coating
Necrosis covering entire leaf blades
Infection of stems, petioles and calyx lobes

What it does to the crop

Reduction of photosynthesis and plant weakening
Wilting and yellowing
Leaf drying and die-back
Yield loss of 30-50%

What encourages it

Air humidity 50-70% (does not require high humidity)
Temperature 20-25°C
Spreading by air currents

Prevention

Humidity control
Greenhouse ventilation
Removal of infected leaves

⚠️ 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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