🐛✗ Tested and false“Scab on an apple tree will spread to a nearby pear tree in the same garden, or the other way round”
Apple scab and pear scab are caused by two different fungal species, Venturia inaequalis on apple and Venturia pyrina on pear. A peer-reviewed review of cross-inoculation studies found these fungi are highly host-specific, with attempts to infect apple with the pear fungus, or pear with the apple fungus, generally failing.
Our read Older references sometimes listed pear as a possible host of the apple fungus and vice versa, but the review notes this has not held up under actual inoculation testing. Treat the two as separate infections that happen to look alike and share a genus name.
What to do: Manage scab on your apple and pear trees as two separate problems. Clearing scab from one doesn't protect the other, but an infected apple tree is not itself the reason a pear tree nearby develops scab.
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“Planting a scab-resistant apple or pear variety means the tree will never get scab”
Named resistant cultivars are real and worth choosing over susceptible ones, but resistance in these fungal disease trials is a matter of degree, not a guarantee. A US university plant disease clinic notes that beyond the well-established resistant list, many other varieties promoted as resistant vary in how well that resistance holds up and may still need further evaluation.
Our read "Resistant" and "scab-proof" aren't the same claim. The named cultivars genuinely cut your risk a long way, which is why they're worth choosing, but they're not documented anywhere as immune, and resistance in fruit trees generally can decline over time as the fungus population shifts.
What to do: Choose a named resistant variety to cut your odds substantially, but keep up autumn leaf clearance and winter pruning as backup rather than assuming the variety alone will keep the tree clear.
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- RHS: Apple and pear scabNames specific resistant apple cultivars, including 'Discovery', 'Lord Derby', 'Winston' and 'Topaz', and resistant pear cultivars including 'Beurre Hardy', 'Hessle', 'Jargonelle' and 'Josephine de Malines'.
- Cornell Plant Disease Diagnostic Clinic: Apple Scab (Venturia inaequalis)Beyond a core list of well-established scab-resistant cultivars, many additional varieties have shown resistance but may require further evaluation to fully determine the degree of their resistance to scab.
“Apples and pears marked with scab are still fine to eat once you cut away or peel off the blemished skin”
A light scab attack only blemishes the skin, and eating quality is barely affected, so there's no reason to bin fruit over a few dark spots. The real problem is cracked fruit: as scab restricts the skin, the fruit distorts and splits, and that opening lets rot get in and stops the fruit storing through winter.
Our read The distinction that matters isn't peeling versus not peeling, it's cracked versus uncracked. A lightly spotted, intact apple needs no special treatment at all; a cracked one should be used or eaten promptly rather than stored, since it won't keep.
What to do: Eat or cook lightly marked fruit as normal. Use cracked or split fruit soon after picking rather than trying to store it, and cut away any soft or rotten patches first.
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- RHS: Apple and pear scabLight attacks only blemish the skin and eating quality is hardly affected, while cracked fruit is prone to rots and won't store well.
“Raking up and destroying fallen leaves in autumn genuinely reduces next year's scab infection”
The fungus overwinters on fallen leaves and releases the airborne spores that start the following spring's infections, so removing that leaf litter removes a real chunk of next year's starting inoculum. This is backed independently by a UK source and two US university extension sources, all naming leaf collection and disposal as a primary, not marginal, control measure.
Our read None of these sources claim it eliminates scab outright, and the RHS is explicit that the benefit is capped unless your trees are isolated, since spores also arrive on the wind from neighbouring gardens. It's a genuine, worthwhile reduction in local spore load, not a cure.
What to do: Collect and destroy fallen leaves and any infected fruit each autumn rather than composting them, and prune out blistered twigs at the same time. Treat it as lowering the odds, not guaranteeing a scab-free tree next year, especially if nearby gardens have infected apple or pear trees too.
3 sources
- RHS: Apple and pear scabPruning out blistered twigs and disposing of fallen leaves and infected fruit reduces the spores available to start next year's infections, though the benefit is limited unless neighbouring trees are also clear.
- Cornell Plant Disease Diagnostic Clinic: Apple Scab (Venturia inaequalis)Collecting and disposing of fallen leaves in autumn helps reduce the inoculum that may cause disease the following spring.
- Iowa State University Extension: Apple ScabBecause the fungus overwinters in leaf litter, sanitation, meaning removing and destroying fallen foliage, is the primary cultural measure and dramatically reduces the amount of pathogen available to infect trees the next year.
“A wet spring makes apple and pear scab worse, so Scottish gardens carry a higher risk than drier parts of the UK”
Scab spores spread by wind and by rain splashing off infected leaves, so both the start of infection in spring and its spread through summer depend on wet conditions. A US university extension source states this plainly: cool, wet spring conditions favour scab, and how bad the disease gets in a given year tracks the weather.
Our read Scotland runs wetter than the UK average across spring and summer, which is a straightforward extension of the weather dependency both sources describe, not a Scotland-specific finding from either source itself.
What to do: In a wet spring, or in a garden on Scotland's wetter west coast, prioritise the non-chemical measures, autumn leaf clearance, pruning out blistered twigs, and choosing a resistant variety, since the weather itself is working against you.
In Scotland: Reasoning applied to Scotland's typically wetter spring and summer rainfall; neither source below makes a Scotland-specific claim.
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“Pruning your apple or pear tree to open up the canopy for airflow genuinely cuts scab risk”
Scab infection depends on leaves staying wet for an extended stretch after rain. A US university extension source states that a properly pruned, open canopy ventilates better and lets leaves dry faster, which cuts the number of successful infections.
Our read This sits alongside, not instead of, the RHS's own pruning advice for this disease, which focuses on cutting out blistered twigs to remove infected wood. The airflow benefit is a separate mechanism: fewer hours of wet leaf surface for spores to establish on.
What to do: Prune during the dormant season to open up a congested canopy, alongside cutting out any blistered twigs, so leaves dry out faster after rain through spring and summer.
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