Late blight: how to spot, prevent and treat it disease

How do you spot late blight?

On the leaves and stems there are dark, watery blotches, spreading fast until the leaf browns and dies. On the underside of a blotch there is a white down. On the fruit there are firm, olive brown patches. In cold wet weather the plant collapses in a few days.

How do you prevent late blight?

Plant healthy stock and keep to the rotation. Give the plants a wider spacing and an airy site. Water under the leaves, never over the foliage. Remove diseased plants as they show and take them out of the garden, not onto the compost. Choose resistant varieties.

What works against late blight?

Copper products work only as a preventive. Once the blotches are visible the disease can no longer be stopped and the only measure is to remove the plant.

Check the registration and the label before use.

Which plants get late blight? 2

Vegetables 2

Sources: Clemson Cooperative Extension, EPPO Global Database, University of Maryland Extension
Checked on 17 August 2026.