Young Autumn Blaze maple 3yrs old with split trunk


hello …I live in Sault Ste. Marie ON. ..a climate with great temp fluctuations. Planted this potted maple and staked it about 3 yrs ago..this fall I noticed the split trunk …about 1 foot long about 3 ft from the ground. Will try to attach picture. Thanks for your help. Brenda removed stake and panty hose I had tied it with.


Thank you for contacting the Toronto Master Gardeners. Unfortunately, your picture was not attached to your question. We receive numerous questions concerning tree trunk damage and split bark at this time of year. The following information from a number of our archived posts.

There is no single reason for bark splitting on trees. During late winter and early spring, severe cold followed by rapid thawing can result in splits referred to as “frost-cracks.” These “frost” cracks can actually start from a wound inflicted earlier in the tree’s development. Sometimes the crack may remain in the internal wood, but frosts can cause the crack to expand and split the bark. Excessively late growth in the fall, stimulated by warm temperatures, high humidity and high nitrogen levels, can increase susceptibility of trees to frost cracking.

Fluctuating growth conditions may also cause splitting of bark. Dry weather (which slows growth) followed by wet or ideal growth conditions may cause an excessive or vigorous amount of growth leading to splits in the bark.

Southwest exposure can also result in bark splitting or frost cracks. On bright sunny days the southwest side of the tree heats up, absorbing the heat of the sun. When the sun sets or goes behind a cloud, there is a sudden freezing of the warm tissue. This sun “scald’ results in the death of the exposed bark. The result is a vertical fissure down the center of the tree trunk, causing strips of bark to peel off, exposing the tree’s inner wood. It is this unequal shrinkage that creates pressure, causing the wood to crack. Frost cracks can extend deeply into the wood of the tree’s trunk. Frost cracks may cause stress for your tree and provide a point of entry for pests and diseases. Damage from sunscald injury may eventually heal.

In summer, sometimes these cracks will expand and close, or partially close, of their own accord. Trees respond to wounding or injury by forming specialized “callus” tissue around the edges of the wound. Thus, the tree responds to the injury by “compartmentalizing” or isolating the older, injured tissue with the gradual growth of new, healthy tissue. Not only do trees try to close the damaged tissue from the outside, they also make the existing wood surrounding the wound unsuitable for spread of decay organisms. Often a raised area of “callus tissue” will develop in the tree’s attempt to close the wound.  However, even a slight opening may be enough to allow insect pests and fungal diseases to infest or infect the tree.

The best defence here is to use good gardening cultural practices to ensure your tree is the healthiest it can be:  make sure you water your tree during drought conditions, avoid compacting the soil around it, remove leaf debris in the fall, and amend your soil with organic fertilizers and mulch (not touching the base of the trunk but in a circle around it).

If you can tell as you head into summer that your tree is not thriving, it may make best to call in a certified arborist.  The Ontario chapter of the International Society of Arboriculture’s website can help you to locate a qualified arborist in your area:

Good Luck