🍅 Tomato How hard it is to control: ★★★☆☆ 3/5

Septoria leaf spot on tomato

Fungal disease occurring mainly on leaves, less often on stems and fruits. Fungus overwinters on plant debris in soil. Development favored by warm and humid weather.

Symptom photos

Septoria leaf spot — Leaf — small dark spots with yellowing of the blade between them — Leaf — small dark spots with yellowing of the blade between them Photo: Dr Parthasarathy Seethapathy, Amrita School of Agricultural Sciences, Bugwood.org, licence CC BY 3.0 us

Septoria leaf spot — Whole leaf — many small spots with a dark margin — Whole leaf — many small spots with a dark margin Photo: MerielGJones, licence CC BY-SA 4.0

Septoria leaf spot — Leaves — brown spots merging into larger necrotic patches — Leaves — brown spots merging into larger necrotic patches Photo: Wolan268, licence CC0

Symptoms

Numerous small, first yellowish, then brown-gray spots on leaves
Spots 2-5 mm in diameter with dark border
Visible black dots (pycnidia) in center of spots
Merging spots leading to drying of entire leaves
Symptoms appear from lower leaves upwards

What it does to the crop

Premature die-back and leaf drop
Plant weakening and yield reduction
Deterioration of fruit quality due to sun exposure

What encourages it

Temperature 20-25°C
High air humidity and prolonged leaf wetness
Dense planting hindering ventilation
Infected plant debris in soil

Prevention

Crop rotation (3-4 years break)
Not too dense planting ensuring ventilation
Soil mulching preventing spore splashing
Avoiding overhead watering (drip irrigation)
Removal of infected leaves and plant debris

⚠️ 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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