Fungal disease
Apple Cedar Apple Rust
A rust fungus that needs both apples and junipers (cedars) to complete its life cycle, leaving bright orange spots on apple leaves.
Symptoms
- Bright yellow-orange spots on leaves in spring and summer
- Small tube-like growths on the underside of spots later in the season
- Early leaf drop on heavily affected trees
What causes it
Spores blow from galls on nearby juniper or cedar trees to apple leaves in wet spring weather.
What you can do
- Check nearby junipers for brown galls and remove them where you can.
- Choose rust-resistant apple varieties.
- If the disease is severe, fungicide sprays from bloom time can help; follow the label.
Not sure it's cedar apple rust?
Photograph one affected leaf and Plantulus will suggest the most likely problem, with a confidence score. It's free and needs no sign-up.
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General guidance only, not a diagnosis. Check product labels and local rules before using any treatment, and ask a horticultural specialist if a valuable plant is struggling. See the disclaimer.