Apple trees diseases and pests
The database lists 6 problems recorded on this crop. 4 of them can cost the whole harvest, and 5 survive in soil or debris into next season — those are the ones that decide your rotation. The largest number are active in March.
Pressure through the year
The number of problems listed as active in each month. Pick a month to see what to sow, plant and harvest then.
Start from what you can see
What actually prevents them
Water at the base of the plant in the morning, never over the leaves. Splashing soil onto foliage is the delivery route for every problem listed here, and morning watering lets anything that does land dry before nightfall.
Applies to: Apple Canker, Cedar-Apple Rust
Mulch the soil surface. A physical barrier between last season's spores and this season's lowest leaves removes the first infection of the year, which is the one that seeds all the others.
Applies to: Apple Canker, Cedar-Apple Rust
Give the plants their full spacing 300×400 cm and keep the centre of each one open. Air moving through the planting dries the leaves faster, and leaf wetness duration is what turns a spore landing into an infection.
Applies to: Apple Scab, Powdery Mildew
Rotate this bed and everything else in the same family on at least a three-year cycle. 5 of the problems below survive in soil or crop debris between seasons, so returning the same crop to the same ground hands them the host they were waiting for.
Applies to: Fire Blight, Apple Canker, Apple Scab, Cedar-Apple Rust and 1 more
Clear and remove the spent crop at the end of the season rather than digging it in. Debris left on the surface is where the persistent problems overwinter, and next spring they start from your own bed rather than from somewhere else.
Applies to: Fire Blight, Apple Canker, Apple Scab, Cedar-Apple Rust and 1 more
Control sap-sucking insects early, before the population is obvious. Several of the problems here are carried plant to plant by aphids or thrips, and once a virus has arrived there is no treatment — only the vector was ever treatable.
Applies to: Fire Blight
Keep affected material out of the compost heap — 2 of these survive a garden heap and come back with the finished compost. Bag it for municipal green waste, which is composted at temperatures a garden heap does not reach.
Applies to: Fire Blight, Apple Canker
Every listed problem
Ordered by how much they can cost you.
Fungal diseases(4)
- Apple CankerSevere
Elliptical sunken patches of dead bark, often centred on a bud or wound, with the bark flaking away in concentric rings. Shoots above a girdling canker die back. White pustules appear on cankers in summer and red-orange ones in winter.
- How it spreads
- Rain and irrigation splash
- Compost
- Keep out of the compost
- Conditions
- 5–20°C · humidity ≥85% · wet leaves / rain
- First move
- Remove affected material now
- Apple ScabSevere
Olive-green to brown velvety blotches on leaves that later turn black; corky, cracked scabby lesions on fruit; early leaf drop in severe cases.
- How it spreads
- Wind-blown spores
- Compost
- Hot compost only
- Conditions
- 6–26°C · humidity ≥80% · wet leaves / rain
- First move
- Treat, then re-check in 5–7 days
Also at risk: Pear trees, Quince
- Cedar-Apple RustModerate
Bright yellow-orange spots on apple leaves and fruit that develop tube-like structures beneath; on junipers, brown galls produce gelatinous orange horns when wet.
- How it spreads
- Rain and irrigation splash
- Compost
- Hot compost only
- Conditions
- 8–24°C · humidity ≥85% · wet leaves / rain
- First move
- Treat, then re-check in 5–7 days
- Powdery MildewModerate
White to grey powdery coating on the upper surface of leaves and stems, later yellowing, curling and premature leaf drop. Fruit may be stunted or sun-scorched as the canopy thins.
- How it spreads
- Wind-blown spores
- Compost
- Hot compost only
- Conditions
- 15–28°C · humidity ≥60%
- First move
- Treat, then re-check in 5–7 days
Also at risk: Cucumbers, Zucchini, Peas, Pumpkins, Grapes, Strawberries
Bacterial diseases(1)
- Fire BlightCritical
Blossoms and shoots suddenly wilt, blacken and bend into a shepherd's crook as if scorched by fire; sunken cankers ooze amber bacterial droplets in warm weather.
- How it spreads
- Carried by insects
- Compost
- Keep out of the compost
- Conditions
- 21–30°C · humidity ≥70% · wet leaves / rain
- First move
- Remove affected material now
Also at risk: Pear trees, Quince
Pests(1)
- Codling MothSevere
Small entry holes plugged with brown crumbly frass on fruit, tunnels bored to the core, premature fruit drop, and pinkish-white caterpillars inside.
- How it spreads
- Carried by insects
- Compost
- Safe to compost
- Conditions
- 15–32°C
- First move
- Treat, then re-check in 5–7 days
Also at risk: Pear trees
Why rotation matters here
5 of these overwinter in the soil or in crop debris rather than on the plant. Pulling the sick plant does not remove them: they wait for the same host to come back to the same ground.