Norway Maple
Acer platanoides
Active Threats to Norway Maple
Maple Tar Spot
Common fungal disease causing black spots on maple leaves. Mostly cosmetic and does not seriously harm healthy trees.
Signs to watch for:
- •Black tar-like spots on leaves
- •Yellow halos around spots
- •Early leaf drop in severe cases
Recommended Action: Rake and dispose of fallen leaves in autumn to reduce spores. No treatment typically needed.
Free consultation available
Overview
Common urban tree but recognized as invasive species threatening native forests
Widely planted as street tree mid-20th century, now recognized as ecological threat
Identification
Leaves
Large 5-7 lobed leaves with milky sap when broken. Leaves remain green late into fall, then turn yellow. Similar to sugar maple but larger and with milky sap.
Bark
Bark develops narrow interlacing ridges with age, distinctly different from sugar maple's vertical plates.
Flowers
Bright yellow-green flowers appear before leaves emerge in early spring, very showy.
Fruit
Paired samaras with wings spreading nearly horizontally (180 degrees), distinguishing from native maples.
Growing Conditions
Climate
Extremely adaptable to wide range of conditions, contributing to invasive nature
Hardiness Zones: 4a, 4b, 5a, 5b
Light Requirements
Soil
Moisture: dry, moist
Drainage: well-drained, moderate
pH Range: 4 - 8
Tolerance
Care & Maintenance
Pruning
Best Season: October-February
Frequency: Minimal once established
- Prune in October-February
- Remove crossing branches
- Establish structure when young
Avoid: Spring when sap is running
Watering
Establishment: Weekly watering for first year
Mature: Very drought tolerant
Seasonal Care Timeline
Spring
- Heavy seed production
- Remove seedlings before they establish
- Early leafing provides competitive advantage
Summer
- Dense shade prevents native plant growth
- Monitor for excessive seedling spread
Fall
- Remove fallen leaves to reduce disease
- Consider replacement with native alternatives
Winter
- Plan for removal and replacement with native species
Common Issues
Invasive Growth
HighAggressive seeding and shade-out of native species
Symptoms: Numerous seedlings, Dense canopy, Poor understory growth
Treatment: Remove seedlings regularly, consider replacing with native alternatives
Prevention: Do not plant new trees, remove existing when possible
Tar Spot
LowFungal leaf disease causing black spots
Symptoms: Black spots on leaves
Treatment: Rake and remove fallen leaves
Prevention: Improve air circulation
Quick Facts
When to Call an Arborist
Recommended inspection: Annual inspection
- •Structural defects
- •Root damage
- •Significant dieback
- •Consider removal and replacement with native species
Free consultation for Belleville residents
Recommended Services
Based on Norway Maple characteristics