Cedar-apple rust
Bright orange spots on apple and crabapple leaves, and jelly-like orange galls on nearby junipers in spring.
What you'll see
- Yellow-orange spots on the upper side of apple and crabapple leaves soon after bloom.
- Later, small tube-like growths under the spots or on the fruit; badly hit leaves drop early.
- Brown, woody galls on juniper or eastern redcedar twigs that sprout orange, jelly-like horns after spring rain.
Why it happens
A rust fungus that needs two hosts: junipers and apples or crabapples. Spores from the juniper galls blow onto apple leaves in wet spring weather, and spores from the apples later infect the junipers.
How to fix it
- Prune galls out of nearby junipers in late winter, before the horns form; spores can still blow in from far away.
- On susceptible trees, spray a fungicide labeled for apple rust from just before bloom until the juniper galls dry up. Follow the label and keep kids and pets away.
- Replace badly hit trees with resistant varieties.
Keep it from coming back
- Plant rust-resistant apples and crabapples, such as Liberty, Enterprise or Priscilla.
- Avoid planting apples and junipers close together.
- Check nearby junipers for galls each spring.
Sources
- Missouri Botanical Garden: Cedar-apple rust
- University of Missouri IPM: Cedar apple rust
- Clemson HGIC: Cedar-apple rust
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.