Fungal disease
Tomato Late Blight
A fast-spreading disease that can kill tomato plants within days in warm, wet weather.
Symptoms
- Dark, water-soaked patches spreading quickly across leaves
- White, fuzzy growth under the leaves in humid weather
- Firm, greasy brown patches on the fruit
What causes it
Spores spread on wind and rain during warm, humid spells, often from nearby potatoes.
What you can do
- Remove and bag infected plants; do not compost them.
- Keep leaves dry: water at the base and grow under cover if possible.
- Grow blight-resistant varieties.
- Keep tomatoes away from potatoes with blight.
Not sure it's late blight?
Photograph one affected leaf and Plantulus will suggest the most likely problem, with a confidence score. It's free and needs no sign-up.
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General guidance only, not a diagnosis. Check product labels and local rules before using any treatment, and ask a horticultural specialist if a valuable plant is struggling. See the disclaimer.