Red Oak
Quercus rubra
Active Threats to Red Oak
LDD Moth (Spongy Moth)
Formerly known as Gypsy Moth. Caterpillars defoliate trees in late spring, with periodic outbreak years causing severe damage.
Signs to watch for:
- •Visible caterpillars with blue and red spots
- •Skeletonized or completely eaten leaves
- •Egg masses on tree trunks (tan, fuzzy patches)
- •Frass (caterpillar droppings) under trees
Recommended Action: Healthy trees typically survive defoliation. Repeated years of heavy feeding may require professional intervention.
Free consultation available
Oak Wilt
Deadly fungal disease spreading north through Ontario. Red oaks are most susceptible and can die within weeks.
Signs to watch for:
- •Rapid wilting starting at leaf edges
- •Leaves turning bronze or brown
- •Defoliation from top of crown down
- •Fungal mats under bark with fruity odor
Recommended Action: Do NOT prune oaks from April through July. If oak wilt is suspected, contact an arborist immediately.
Free consultation available
Overview
Important native forest tree, valuable for wildlife habitat and timber
Red oak forests historically dominated mixed hardwood stands in Eastern Ontario
Identification
Leaves
Large alternate leaves with 7-11 pointed lobes ending in bristle tips. Leaves turn red to russet-brown in fall.
Bark
Young bark is smooth and gray-brown, developing into thick, vertical ridges with flat-topped appearance on mature trees.
Flowers
Inconspicuous yellow-green catkins appear in spring as leaves emerge.
Fruit
Large acorns (2-3 cm) with flat, shallow caps covering only the top quarter. Mature in second year, important wildlife food source.
🦆 Valuable wildlife food source
Growing Conditions
Climate
Excellent adaptation to Eastern Ontario climate with strong cold and wind tolerance
Hardiness Zones: 3, 4a, 4b, 5a, 5b
Light Requirements
Soil
Moisture: dry, moist
Drainage: well-drained
pH Range: 5 - 7.5
Tolerance
Care & Maintenance
Pruning
Best Season: December-March
Frequency: Minimal pruning needed once established
- Prune in December-March when dormant
- Remove dead or damaged branches
- Establish strong structure when young
Avoid: Spring and summer to prevent oak wilt spread
Watering
Establishment: Deep watering weekly for first 2-3 years
Mature: Drought tolerant once established
Seasonal Care Timeline
Spring
- Oak wilt risk if pruned during active season (primarily southwestern Ontario concern)
- Late frost can damage emerging leaves
- Monitor for spongy moth activity
Summer
- Watch for oak wilt symptoms
- Monitor for defoliating insects
- Young trees may need supplemental water during drought
Fall
- Acorn drop can be heavy
- Fall color display variable by year
- Good time for structural pruning if needed
Winter
- Heavy snow load on branches
- Check for spongy moth egg masses
Common Issues
Oak Wilt
SevereFatal fungal disease affecting vascular system. Present primarily in southwestern Ontario, not yet widespread in Belleville area but remains a concern
Symptoms: Wilting from top down, Leaf discoloration, Rapid decline
Treatment: Remove infected trees immediately
Prevention: Avoid pruning in spring/summer, paint wounds immediately
Professional arborist recommended
Spongy Moth
ModerateDefoliating caterpillar that feeds on oak leaves (formerly known as Gypsy Moth)
Symptoms: Leaf damage, Defoliation, Caterpillar presence
Treatment: Burlap bands to trap caterpillars, biological controls
Prevention: Monitor egg masses in winter, remove when found
Quick Facts
When to Call an Arborist
Recommended inspection: Annual inspection recommended
- •Wilting leaves during growing season
- •Sudden branch dieback
- •Fungal growth on trunk
- •Significant lean or cracks
- •Heavy pest infestation
Free consultation for Belleville residents
Recommended Services
Based on Red Oak characteristics