🥔 Potato How hard it is to control: ★★★★★ 5/5

Late blight of potato

The most dangerous potato disease caused by an oomycete (fungal-like organism, not a fungus sensu stricto). Historically responsible for the Great Famine in Ireland. Spreads lightning-fast.

Symptom photos

Late blight of potato — Leaves — spreading, grey-brown patches of rot — Leaves — spreading, grey-brown patches of rot Photo: Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org, licence CC BY 3.0 us

Late blight of potato — Leaf in the crop — lesion with a paler, sporulating margin — Leaf in the crop — lesion with a paler, sporulating margin Photo: Howard F. Schwartz, Colorado State University, Bugwood.org, licence CC BY 3.0 us

Symptoms

Dark brown spots on leaves
Whitish coating
Rotten tubers

What it does to the crop

Complete yield loss in 5-7 days without intervention
Tuber infection and storage impossibility
Can destroy entire crop in the area

What encourages it

High humidity
Temperature 15-20°C
Prolonged leaf wetness

Prevention

Healthy seed material
Resistant varieties
Destruction of plant debris
Frequent inspection

⚠️ 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.

Keep the disease atlas with you in the garden

In the app you can identify a disease from photos, work out the spray dose for your own bed and log the treatment in your task calendar. Free, no sign-up, works offline.

Open the atlas in the app →

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