When there is a period of cold winter nights followed by warm, sunny days, cracks may appear in a tree trunk, caused by freezing and then rapid thawing. We see this most often in maples and sycamores but it also occurs in many other species. These cracks provide points of entry for insects and diseases.
Once cracks have occurred, there’s little that can be done. Sealants are actually detrimental to the healing process. Keep the tree healthy so it can heal as quickly as possible. Provide water during dry spells and fertilize as needed.
To prevent cracks or to keep cracks from reopening in subsequent years, wrap young trees with tree wrap for the winter. Remove the tree wrap in early spring. Leaving the wrap on provides a protected area for insects and disease organisms. Once the tree has developed thicker bark, wrapping will no longer be necessary.