The cracks occurred in the tree bark are highways for diseases. Untreated, this issue is drastically shortening tree’s lifespan.
When it happens
Bark cracking occurs most often due to frostiness.
Alternating the hot and frosty periods are much more dangerous for trees than extreme frosts.
How to fix those cracks and splits
For this operation we need a sharp knife or a chisel well sterilized with alcohol or with a chlorine solution.
The affected bark area is removed, and if the trunk is also cracked, scratch that crack too.
Apply immediately a solution of Bordeaux mixture or another copper-based fungicide using a brush, in a concentration 10 times higher than the one indicated for regular treatments.
Once the fungicide dries, the scar is “sealed” with a polyurethane varnish (furniture lacquer).
Image Credits: Gardenweb