Apple and pear scab: spots on leaves and fruit

What is scab and how to recognise it?

Scab is a fungal disease caused by the fungus Venturia inaequalis on apple and Venturia pirina on pear, extremely common on both fruit trees in the temperate maritime climate of Belgium and the Netherlands. The fungus overwinters in fallen leaves on the ground and in twig crevices. In spring, when leaves are just emerging and it is moist, the fungus spreads via spores. You recognise scab by olive-green or brown-black spots on leaves, young twigs and green fruit. On mature fruit, brown, corky scars appear; you sometimes even see those on apples sold in shops (not toxic, just cosmetically unpleasant).

The fungus itself is not toxic: the flesh under the scar stays healthy and tastes fine to eat. This distinguishes scab from damage by insects or bird pecking. The danger is that severe infection causes leaf drop, weakening the tree. A fully defoliated tree by July cannot set a good crop the following year.

Why weekly fungicide spraying is not needed

Most fruit growers think you must fight scab with weekly fungicide sprays from August to September. Wrong. Especially because such spray schedules only work if you start in May (preventively) and because the most effective substances against Venturia are harmful to the environment. In the Netherlands and Belgium, glyphosate is banned for private use, and many fungicides for fruit trees are restricted.

The good news: you prevent scab without chemicals. You use logic, clear fallen leaves, and choose resistant varieties. An apple tree you never spray usually grows stronger and bears more fruit than one you spray every week.

Step one: clear fallen leaves in September and October

This is absolutely critical. All scab fungal spores sleep through the entire winter in fallen leaves. If you rake and compost all leaves around your apple or pear tree in October, you remove 80-90% of next year's fungus. This means more thorough cleaning than you might be used to: not just directly under the tree but at least a 1.5 metre circle around the trunk.

What do you do with the leaves? Do not throw them in your regular compost bin. Compost temperature does not reach 60 degrees everywhere (the temperature at which Venturia spores die). Options:

1. Dispose of leaves in your green waste bin or municipal composting facility.
2. In a separate leaf bin (separate from your other compost) stack them for at least two years. After two years the spores are dead.
3. Shred leaves and work directly into soil under the tree (not as mulch on top).

Many gardeners note: if you have no scab-prone tree nearby, you can in October mow grass or clover and place that directly under the tree as mulch. This smothers fallen leaves and prevents scab from spreading in spring.

Step two: prune for airy canopy: prevention through ventilation

A dense, dark tree is a scab paradise. The fungus loves moist, airless conditions. An open canopy dries faster after rain, and sunlight also helps. January pruning is essential: remove all dead wood, inward-growing twigs, and branches that cross each other. Aim for a vase or open-centre form (open basket) so you can see into the heart of the tree.

How hard do you prune? For young trees: so-called "open vase": three to five evenly spaced primary branches from the trunk, growing without touching each other. For mature trees: annual thinning: every twig thicker than your thumb? Likely worth removing. Is it blocking airflow or light? Remove it. This sounds aggressive, but your tree is stronger with the extra light, and scab has less chance.

Another advantage: an open tree is easier to harvest and you spot diseases (scab, insects) faster.

Scab-resistant varieties: Topaz, Santana and others

This is the golden solution if you want apples without scab. Some varieties have scab resistance genetically built into their DNA. Two of the best available are:

Topaz: American red apple, moderately resistant to scab, good for applesauce and fresh eating, harvest October. Good with another apple for pollination. Plant in full sun and sheltered spot.

Santana: Dutch yellow apple, excellent scab resistance, sweet, crispy, harvest October-November. Much easier than many older varieties (Cox, Elstar, Discovery). Also works as a single tree (limited pollination needed).

Other possibilities: Cameo, Freedom (North America), Liberta (Germany). Ask your local garden centre which resistant varieties are available for your region. Not sure which variety suits your garden? On gardenworld.app you can see it first in a preview of your own garden.

If you already have a susceptible apple tree (e.g. Cox Orange Pippin, Ingrid Marie), do not replace it straight away. It can still crop well with a bit more care (see the step-by-step section). Replace it only if scab ruins more than half the harvest year after year.

Remove sick twigs in summer: prevention during growing season

In May-June, if you see scab-infected twigs (brown spots, patches of leaves dropping early), cut them out. This does not spread disease if you disinfect your secateurs with 70% ethanol after each cut. It sounds tedious, but you prevent worse.

Also helps to do a LIGHT prune in May: remove the densest twig clusters so rain drips faster from the canopy. Not in June (birds nesting). May is fine.

No spray schedule needed: why this article does not give a poison schedule

You will find many "scab prevention schedules" online: May this, June that, September more. These are often recommendations for biological fungicides (sulphur, copper) allowed in the Netherlands and Belgium, but even those are unnecessary if you do steps 1 to 5 properly. Sulphur also only works preventively (before infection), not as a cure.

For a small private fruit tree, system management helps more than toxins. A garden is not a factory.

Step by step

Step 1: October, clear fallen leaves

Rake all leaves around your tree (at least 1.5m radius). Place in green waste or separate leaf bin. This is the most important.

Step 2: January, prune for airiness

Prune for open-vase form. Remove dense wood, inward growth, crossing branches.

Step 3: May-June, remove diseased twigs

Check tree for brown spots, cut out sick twigs. Disinfect secateurs between cuts.

Step 4: June-August, observe

Monitor the tree. With steps 1-3 done, scab usually reduces.

Step 5: Harvest August-October

Harvest on time. Harvesting reduces scab because you remove infected fruit.

Step 6: Next October, repeat leaf clearing

Clear leaves, year two. Scab decreases.

Frequently asked questions

Can I eat apples with scab scars?

Yes, completely safe. The scar looks unsightly but the flesh underneath is perfectly healthy. Apples with scab taste just as good. For appearance you peel them or make applesauce.

My pear tree has much more scab than my apple tree. Why?

Pears are more susceptible. Some varieties (e.g. Conference) get scab easily. Apples and pears each have their own Venturia species (Venturia pirina on pear). For pears, prevention is even more critical: leaf removal is really essential. Consider a resistant variety if you want pears.

Can I still prevent scab after January pruning?

Yes, but pruning is prevention (ventilation helps), not cure. If you see much scab in March-April, January was perhaps too late. Prune earlier next year. Removing infected twigs in May still helps.

How many years until scab reduces?

Usually year two. If you clear all leaves in October-November of year 1 and prune well in January of year 1, you will see far fewer brown spots in May-June of year 2.

See it in your own garden first

Want to see how your apple or pear tree could look in your garden with better care? Upload a photo of your garden on gardenworld.app and view a free preview design with healthy fruit trees, good tree form and open canopies. The sharp image with a full plant list costs 7.99, one time only, no subscription.