Tree Pests & Diseases
Crabapple Tree Maintenance
Crabapples are popular ornamental trees for spring flowers and colorful fruit, but they can be prone to apple scab, fire blight, cedar-apple rust, aphids, and other common apple-family issues in Colorado.
- Species
- Crabapple Tree
- Botanical Name
- Malus spp. — ornamental crabapple varieties
- Group
- Ornamental Trees
- Tracked Problems
- 7
Seasonal Calendar
| Problem | Type | Active Season |
|---|---|---|
| Apple scab | Fungus | Spring–Early Summer |
| Fire blight | Bacteria | Spring–Summer |
| Cedar-apple rust | Fungus | Spring–Summer |
| Aphids | Insect | Spring–Fall |
| Scale insects | Insect/scale | Spring crawlers; visible year-round |
| Spider mites | Mite | Summer |
| Environmental stress | Abiotic | Summer–Fall |
Pest & Disease Guide
Apple Scab
Common symptoms
- Dark leaf spots
- Premature leaf drop
Treatment & management
- Clean up leaves
- Improve airflow
Fire Blight
Common symptoms
- Blackened twigs
- Shepherd’s crook tips
Treatment & management
- Prune infected branches
- Sanitize tools
Cedar-Apple Rust
Common symptoms
- Orange spots on leaves
- Defoliation
Treatment & management
- Reduce nearby juniper source
- Treat severe cases
Aphids
Common symptoms
- Leaf curl
- Honeydew
Treatment & management
- Rinse foliage
- Encourage predators
Scale Insects
Common symptoms
- Bumps on bark
- Canopy thinning
Treatment & management
- Treat crawler stage
- Horticultural oil
Spider Mites
Common symptoms
- Bronzed leaves
- Fine webbing
Treatment & management
- Increase irrigation
- Rinse canopy
Environmental Stress
Common symptoms
- Leaf scorch
- Poor flowering
Treatment & management
- Deep watering
- Mulch base
When to Worry
- Repeated fire blight
- Heavy defoliation from scab
- Declining canopy
Mostly Cosmetic
- Minor spotting
- Light aphids
- Occasional mite damage
Notes
These issues can reduce flowering and long-term vigor.
These usually improve with seasonal care and pruning.
Related Resources
Related Services
Great Western Tree Care
When you want a professional opinion
The Root exists to help you understand your landscape. When a tree needs hands-on evaluation, a Great Western arborist can look at it in person.