Tomato blight

Tomato blight is a disease that attacks the foliage and fruit of tomatoes, causing rotting. It is most common in warm, wet weather, and in some years can cause almost total yield loss, particularly of susceptible tomato cultivars grown outdoors. The same pathogen also affects potatoes.

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Tomato blight affecting a fruit cluster

Quick facts

Common name: Tomato blight, late blight
Scientific name: Phytophthora infestans
Plants affected: Tomatoes
Main symptoms: Brown & rotting, shrivelled leaves. Decay of fruit
Caused by: Fungus-like organism
Timing: Early summer onwards

What is tomato blight?

Tomato blight (also known as late blight) is a disease caused by a fungus-like organism that spreads rapidly through the foliage and fruit of tomatoes in warm, wet weather, causing collapse and decay.

It can be a very serious disease on outdoor tomatoes. Tomatoes grown in greenhouses are less likely to be affected but can still suffer badly at times.

Blight is specific to tomatoes, potatoes (on which it is known as potato blight) and some ornamental relatives of these two crops. Cases have been recorded on ornamental Solanum species (e.g. S. laciniatum), and also very occasionally on Petunia.

Symptoms

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