Understanding Winter Sunscald: Why You May Be Seeing Bark Cracking And Splitting On Your Trees
- John Powell
- Jan 20
- 4 min read
Bark Cracking And Splitting On Trees
As a Certified Arborist serving Chicago's western suburbs, one of the most common questions I receive from homeowners during spring inspections is about mysterious vertical splits and discolored bark on their trees. This condition, known as winter sunscald, affects many landscape trees in our region in the form of bark splitting and cracking, particularly those recently planted or situated in exposed locations. Understanding this issue is crucial for protecting your valuable landscape investments.
What is Winter Sunscald?
Winter sunscald is a form of bark damage that occurs during late winter and early spring, particularly on the southern and southwestern sides of trees. Think of it as a severe sunburn for your tree, but with potentially more serious consequences. According to the Morton Arboretum in Lisle, Illinois, this condition affects hundreds of trees annually in the Chicago region.
Why Chicago Trees Are Particularly Vulnerable
Our region's climate creates perfect conditions for sunscald:
Dramatic temperature fluctuations (often 30°F or more in a single day)
Intense winter sun reflection off snow
Long periods of freezing temperatures
Strong prevailing winds
The Science Behind the Damage
During winter days in Chicago, the sun can warm bark temperatures to 45°F or higher on the southern side of the tree, even when air temperatures remain below freezing. As night falls, these warmed tissues rapidly refreeze, causing cells to rupture and die. This cycle of warming and freezing leads to:
Bark splitting
Tissue death
Formation of sunken, discolored areas called cankers
Potential entry points for decay organisms
Most Susceptible Species
In the Chicago area, certain species show higher vulnerability:
Young maples (especially newly planted Norway and Sugar Maples)
Honey Locust
Linden
Crabapple
Young Oak trees
Fruit trees
Identifying Winter Sunscald
Look for these telltale signs:
Elongated, sunken areas of bark
Cracking or splitting bark
Discoloration on the south/southwest side
Exposed wood beneath damaged bark
Vertical strips of damaged tissue
Prevention Strategies
As your local tree care expert, I recommend several proven prevention methods:
Trunk Wrapping
Professional-grade tree wrap, applied from late October through March, provides essential protection. This should be done by a qualified professional to ensure proper application and timing.
Strategic Placement
When planning new plantings, consider locations that provide afternoon shade or protection from intense winter sun.
Proper Pruning
Maintaining appropriate crown structure helps protect the trunk through natural shading. This requires expertise in proper pruning techniques and timing.
Treatment Options
If your tree has already experienced sunscald damage, we can help:
Professional assessment of damage extent
Proper pruning of damaged areas
Implementation of prevention strategies
Monitoring for secondary issues
Long-term Impact on Tree Health
While sunscald itself rarely kills mature trees, it can:
Create entry points for diseases
Reduce property value
Affect tree aesthetics
Lead to structural issues if left untreated
Professional Care Makes the Difference
As a Certified Arborist serving the western suburbs, I've seen how proper care can prevent and manage sunscald issues. Professional intervention often makes the difference between a tree's decline and its recovery.
Conclusion
Winter sunscald is a significant concern for Chicago area homeowners, but with proper understanding and professional care, it's manageable. At Prairie Tree Care, we specialize in helping homeowners protect their valuable landscape investments through educated care and prevention strategies.
Frequently Asked Questions
Q: How quickly can sunscald damage occur? A: Damage can occur in as little as one winter season, with visible symptoms often appearing in early spring.
Q: Can a tree recover from sunscald without intervention? A: While trees can compartmentalize damage, professional intervention greatly improves recovery success and prevents secondary issues.
Q: Does winter sunscald affect property value? A: Yes, visible bark damage can impact curb appeal and overall property value, especially on specimen or focal point trees.
Q: How often should protective wrapping be checked? A: Professional-grade wrapping should be inspected monthly during winter and removed promptly in spring to prevent other issues.
Q: What's the best time to treat sunscald damage? A: Early spring assessment and treatment yields the best results, allowing trees to use their natural growth cycle for recovery.
Q: Can mature trees get sunscald? A: While young trees are most susceptible, mature trees can develop sunscald after severe winters or following significant pruning that exposes previously shaded bark.
Resources for Tree Owners
The University of Illinois Extension Tree Care Guide provides excellent information for homeowners, and local resources like the DuPage County Forest Preserve and Kane County Natural Resources offer additional guidance specific to our region.
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References:
For professional assessment of your trees' winter protection needs, contact Prairie Tree Care. As members of the Illinois Arborist Association, we stay current with the latest research and best practices in tree care for our region.
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