Walnut blight

Black greasy spots on leaves and young walnuts, which may drop: a bacterium favoured by a wet spring.

How to recognise

• Look at young walnuts: sunken, greasy black spots indicate blight.
• Check leaves and young twigs for angular black spots.

What to do

• Collect and dispose of affected nuts and leaves to reduce contamination.
• Open the crown with suitable pruning so it dries quickly after rain.

Prevent

• Where possible choose late-leafing varieties, less exposed to spring rains.

Trees affected