Disease

Apple scab

Olive-green to black scabby spots on apple and crabapple leaves and fruit, worst after cool, wet springs.

What you'll see

• Velvety olive-green spots on young leaves in spring that darken to black; badly hit leaves yellow and drop early.
• Dark, scabby, sometimes corky spots on the fruit, which may crack or grow lopsided.
• Blistered, scabby twigs on some trees, especially pears.

Why it happens

A fungus survives the winter on fallen leaves. In spring, rain splashes and blows its spores onto new leaves and fruit, which get infected when they stay wet for hours.

How to fix it

1. Rake up and bin fallen leaves and scabby fruit, so less fungus survives to the next spring.
2. Prune out blistered, scabby twigs in winter, cleaning your pruners between cuts.
3. Lightly scabbed fruit is still fine to eat; peel or cut away the spots.
4. In rainy springs, a fungicide labeled for apple scab, sprayed as the leaf tips emerge, protects new leaves; follow the label and keep kids and pets away.

Keep it from coming back

• Plant scab-resistant apple and crabapple varieties.
• Clear away fallen leaves every autumn.
• Keep sprinklers off the leaves and fruit in spring.

Sources

• UC IPM: Apple and pear scab
• RHS: Apple and pear scab
• University of Maryland Extension: Apple scab disease

General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.