Brown, rough patches on the apples and spotted foliage: apple scab is the classic among fruit tree diseases and, in wet years, almost unavoidable. But while commercial growing sprays against it, in the home garden you take a smarter path.
Because against scab, above all the right choice of variety helps. Whoever plants a scab-resistant apple has practically solved the problem before it arises. This article is the detail edition to the overview in Recognising fruit tree diseases.
How to recognise apple scab
The fungus Venturia inaequalis shows first on the leaf: olive-green, velvety-looking patches that later turn brown. In heavy attack the leaves yellow and drop early. On the fruit form the typical dark, corky, cracked scab patches.
Its timetable is tightly tied to wetness. The fungus overwinters in the fallen leaves on the ground. In spring, in rain, it hurls its spores onto the young leaves, where they germinate in the damp film. A wet, mild spring is therefore a scab year, a dry one often stays spared.
Resistant varieties are the best protection
Instead of fighting the scab year after year, you deny it its basis with the right variety. In recent decades many scab-resistant apple varieties have been bred that give even the home gardener healthy fruit without any spraying.
How to make your apple scab-proof
- Choose a scab-resistant variety
Varieties like Apple 'Topaz', Apple 'Santana', Apple 'Rewena' or Apple 'Florina' are bred specifically for scab resistance. When planting anew, that is the most important step of all.
- Keep the crown airy
A regular cut lets light and air into the crown, the foliage dries quickly and the fungus finds fewer damp surfaces to attack. More on it in Summer pruning of fruit trees.
- Remove the fallen leaves
In autumn, gather the fallen leaves under the tree or chop them small with the lawnmower. That takes the fungus's winter quarters and its start into the next year.
- Sunny, airy site
A free, airy site dries faster than a damp, still corner. Right at planting you thus lay the foundation against scab.
Against scab, the variety helps more than any spray. A resistant apple in an airy spot makes the problem needless.
The core rule against apple scab
Frequently asked questions
How do I reliably recognise apple scab?
By olive-green to brown, velvety patches on the leaves and dark, corky, cracked patches on the fruit. It appears above all in wet springs and usually begins on the leaf.
Do I have to spray against scab?
Not in the home garden. Spraying is a matter for commercial growing with susceptible dessert varieties. At home you solve the problem far more simply through a scab-resistant variety, an airy crown and removing the fallen leaves.
Which apple varieties are scab-resistant?
Proven ones are, for example, Apple 'Topaz', Apple 'Santana', Apple 'Rewena', Apple 'Florina' or Apple 'Retina'. When buying, look explicitly for the note scab-resistant.
Can I still eat scabby apples?
Yes. You cut off the corky scab spots, the rest is fine. Scab is above all a visual flaw and does not make the fruit toxic or unhealthy.
Does the pear get scab too?
Yes, pear scab, caused by a closely related fungus. Symptoms and prevention are the same as with the apple. Here too, robust varieties and an airy crown help best.
