Spotting and containing tomato blight
Difficulty: Easy · Time: approx. 15 minutes
Late blight is the most common tomato disease. It appears mainly in warm, damp summers and can ruin a plant within a few days – so spotting it early is half the battle.
An infection can't be cured, but it can be contained and prevented. This guide helps you tell the symptoms apart from harmless spots and react correctly. A photo of the leaf underside helps with identification.
What you'll need
- Clean scissors or knife
- Bin bag (infected material goes in general waste, not compost)
- Gloves
- Optional: a rain cover or sheeting for protection from wet
- Optional: an approved plant protection product
Step by step
- 1
Recognise the symptoms
Typical signs are brown-grey patches on leaves, often with a yellow edge, and a grey-white fungal coating on the leaf underside. On the fruit you see brown, hard, sunken areas.
- 2
Remove affected parts
Cut out affected leaves, shoots and fruit generously. With heavy infection, sacrifice the whole plant to save its neighbours.
- 3
Dispose of it properly
Put everything infected in general waste, never on the compost – the spores survive there and return next year. Clean your tools afterwards.
- 4
Keep plants dry
The fungus needs moisture. Water only at the roots from below, never over the leaves, and use a rain cover and spacing so the foliage dries quickly.
- 5
Prevent it next season
Enough spacing, regular pruning of side shoots, mulch against splashing soil and crop rotation (don't plant tomatoes in the same spot each year) cut the risk significantly.
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Upload a photo →Frequently asked questions
- Can I still eat affected tomatoes?
- Not the affected, brown, rotten fruit. Healthy, flawless fruit from the same plant can be picked and used – when in doubt, cut away generously.
- Is this the same as blossom-end rot?
- No. Blossom-end rot (a brown, leathery patch at the base of the fruit) isn't a fungus but a calcium deficiency from uneven watering – you treat that quite differently.
- Do I have to replace the soil?
- In a bed, crop rotation is usually enough: no tomatoes or potatoes in the affected spot for a few years. In pots, renew the soil and clean the container.