Apple Scab: Symptoms, Resistant Varieties and How to Control It

By the Garden Voila editorial team · Updated October 30, 2026 · How we verify

Apple scab is the most common disease of apples and crabapples, caused by the fungus Venturia inaequalis. It produces olive-green to dark brown, velvety spots on leaves in spring, which later turn black and may cause leaves to yellow and drop, and dark, rough, corky “scabs” on fruit that can crack and deform it. It thrives in cool, wet springs. To manage apple scab, plant scab-resistant varieties, rake and destroy fallen leaves in autumn or shred them with a mower to speed decay, prune trees to an open canopy so leaves dry quickly, and, on susceptible varieties in rainy areas, apply a protective fungicide labeled for apple scab from bud break through about a month after petal fall, especially before and during rain.

Apple scab in brief

What causes apple scab?

The Wikipedia article on Venturia inaequalis explains the fungus’s life cycle: it survives the winter in infected leaves on the ground, where it forms tiny fruiting bodies. In spring, from about bud break onward, these release ascospores during rain, which are carried by wind to young leaves and blossoms. If the leaves stay wet long enough, the spores germinate and infect. Spots appear within one to three weeks and produce secondary spores (conidia), which are splashed by rain to other leaves and fruit throughout the season. The Penn State Extension guide to apple scab in the home fruit garden notes that controlling these early spring infections is the key to preventing a season-long problem.

How do you recognize apple scab?

• Olive-green spots with feathery, velvety edges on the undersides of young leaves in spring, then on upper surfaces.
• Spots that turn dark brown to black and may merge, giving leaves a sooty look.
• Twisted, puckered or yellowing leaves that drop early, sometimes by midsummer on very susceptible trees.
• Round, dark, rough or corky scabs on fruit, often with cracks.
• Deformed or small fruit that may drop early.
• Pin-point scab: tiny black spots that appear on stored fruit infected late in the season.

Leaf spots from cedar-apple rust are bright orange-yellow rather than olive-black, and frogeye leaf spot has purple-bordered tan spots. See cedar-apple rust for that disease, and use the plant problem identifier if you are unsure.

Why does apple scab matter?

Scabby fruit is still safe to eat; the scabs are only skin-deep and can be peeled away. But severe scab causes misshapen, cracked fruit that does not store well, early leaf drop that weakens the tree and reduces next year’s flowering, and, in very wet years, the loss of most of the crop on susceptible varieties. Ornamental crabapples that are susceptible can lose most of their leaves by midsummer, making them unsightly. Over several years, repeated defoliation weakens trees and makes them more prone to winter injury and other problems.

Which apple varieties resist scab?

Many scab-resistant varieties were bred by the cooperative PRI program (Purdue, Rutgers and Illinois), and their names often include “pri” or “free.” If you are planting new trees in a wet or humid climate, choosing a resistant variety eliminates most of the need for sprays. See our guides to Liberty apple trees, heirloom apples and dwarf apple trees when choosing trees. For crabapples, many modern disease-resistant cultivars are available; see crabapple trees.

How do you control apple scab without chemicals?

1. Clean up fallen leaves in autumn. Rake and bag or compost leaves in a hot pile, or run a mower over them several times to shred them, which speeds decay and can reduce spring spore numbers dramatically.
2. Apply urea or compost to fallen leaves in fall: a light spray of 5 percent urea on fallen leaves speeds their breakdown in some orchard programs; shredding plus a nitrogen source has a similar effect.
3. Prune for air flow during the dormant season, opening the canopy so leaves and fruit dry quickly after rain. See when to prune apple trees.
4. Thin fruit so clusters do not touch, which helps them dry.
5. Space trees generously and avoid planting in low, damp spots.

When should you spray for apple scab?

For susceptible varieties in rainy climates, protective fungicides are applied during the primary infection period in spring, from green tip (when leaf tips first show) through about four to six weeks after petal fall, typically every 7 to 10 days and before forecast rain. Spraying after symptoms appear is much less effective. Options for home gardeners include sulfur, captan, myclobutanil and some copper products, each with specific labels for timing and crops; some are allowed in organic growing. Copper can russet fruit if used after bloom. Do not spray open blossoms when bees are active. See copper fungicide for more on copper.

Is scabby fruit safe to eat?

Yes. Apple scab does not make fruit unsafe. Scabs are confined to the skin, so peel affected areas and use the fruit fresh, cooked or for cider. Badly cracked fruit may rot sooner, so use it first, and do not store scabby apples with your best keepers. See how to store apples for storage tips and hard apple cider for using blemished fruit.

Apple scab on crabapples and pears

The UConn Home and Garden Education Center fact sheet on apple scab highlights resistant cultivars and sanitation as the most effective tools for home gardeners.

Crabapples are affected by the same fungus. Susceptible ornamental crabapples can lose most of their leaves by midsummer; replacing them with resistant cultivars is often the best long-term solution. Pear scab is caused by a related fungus, Venturia pyrina, and is managed in a similar way with leaf cleanup, pruning and resistant varieties.

Dealing with more than one problem? Our plant pests and diseases guide lists every insect and disease we cover, organized by symptom.

Apple scab FAQ

How does weather affect apple scab infections?

Scab infections depend on how long leaves stay wet and how warm it is. At around 60 to 75°F, as few as 9 to 12 hours of continuous wetness can be enough for infection; at cooler temperatures, longer wet periods are needed. This relationship, worked out by researchers and often called the Mills table, is used by commercial orchards and some extension weather services to predict infection periods. For home gardeners, the practical lesson is simple: long, soaking spring rains and drizzly, foggy days around bloom are the highest-risk times, so that is when protection matters most for susceptible varieties. Dry springs can mean very little scab, even on susceptible trees.

Should you remove scabby leaves from the tree?

Removing a few infected leaves by hand can reduce secondary spread on small trees, but it is not practical on larger trees and does little once the disease is widespread. Focus your effort on autumn cleanup of fallen leaves, which is where the fungus overwinters and where next spring’s infections begin. In small gardens, raking every leaf under susceptible trees, or mowing them into tiny pieces and adding them to a hot compost pile, can reduce spring scab pressure by a large amount.

Is apple scab worse in some regions?

Yes. Apple scab is most severe in regions with cool, wet springs, such as the northeastern and north-central US, the Pacific Northwest west of the Cascades, Canada, the UK and northern Europe. In arid regions with dry springs, such as much of the intermountain West and California’s Central Valley, it is uncommon. If you garden in a wet-spring region, resistant varieties are especially valuable, because they can save you from spraying every spring.

Do neighboring trees matter?

Spores can blow from nearby unmanaged apple and crabapple trees, so cleaning up only your own leaves helps but may not eliminate scab if neighbors have heavily infected trees. Resistant varieties are the best defense where you cannot control nearby sources.

Apple scab vs other apple problems

For insect damage, see worms in apples, and for fire blight, see fire blight. Getting the diagnosis right means you treat the real problem at the right time.

With resistant varieties, good fall cleanup and an open, well-pruned canopy, most home gardeners can keep apple scab at a level where it no longer spoils the harvest.

Can you graft a resistant variety onto a scabby tree?

Yes. Topworking, grafting a scab-resistant variety such as Liberty or Enterprise onto the branches of an established susceptible tree, can convert it over a few years without losing the root system. It is a good project for keen gardeners; see grafting apple trees for methods and timing.

Keep records of how scab looked each year alongside your spring weather, and you will soon learn how much protection your trees really need.

Many gardeners discover that resistant varieties and good cleanup let them skip sprays entirely in most years.

Does apple scab affect apple trees in containers?

Yes, potted dwarf apples get scab too, but they are easy to protect: move them under cover during long spring rains, clean up fallen leaves from the patio, and choose a resistant variety from the start.

Rake, prune, and choose resistant varieties: those three habits handle most apple scab in home orchards without much effort at all.

Good luck with your harvest this year.

Further reading: Penn State Extension, Apple Scab in the Home Fruit Garden; UConn Home and Garden Education Center, Apple Scab; Wikipedia, Venturia inaequalis.

Scab biology, spray windows and resistant varieties

University of California IPM’s apple and pear scab guide explains the cycle. Yellow spots turn dark and olive on leaves, fruit and sometimes stems; fruit lesions begin velvety grey-black, then become sunken and tan, and fruit can distort, crack and drop. The fungus overwinters mainly in infected leaves on the ground, and rain or sprinklers release spores in spring. Infection is fastest at 55 to 75°F (13 to 24°C) and requires leaves or fruit to stay continuously wet for at least 9 hours. Secondary spores form 8 to 17 days after primary infection. If spring is dry from green tip through fruit set, scab is usually not a problem.

• Cultural: for a single backyard tree, remove fallen leaves in autumn or winter and compost or destroy them. If sprinklers wet foliage, irrigate between sunrise and noon.
• Spray timing: sprays are needed only when rain is likely and leaves stay wet 9 or more hours. Dormant-season treatments are not effective. The window runs from bud break to one month after petal fall; if no infections appear by then, sprays can usually stop.
• Options: copper and Bordeaux from green tip to full bloom only (later use can russet fruit); wettable sulfur through bloom and early fruit set, not within 3 weeks of an oil spray or near 90°F; myclobutanil is a synthetic option. Organically acceptable choices include copper, copper soap, sulfur and mineral or neem oils.

See our fruit trees hub for related care.

Reviewed October 2026. Sources: University of California IPM, Apple and Pear Scab