Young trees and those with smooth, thin bark are prone to two problems in winter: browsing and frost cracking.
Animal Browsing. Small animals, such as field mice and rabbits, will gnaw at tree bark when other food is hard to find in winter. The wounds offer an entry point for insects and disease. And if the gnawing goes around most of the trunk, the tree can die.
Frost Cracking. This is also known as “southwest injury” because it is most likely to occur on the southwest side of a tree. On warm winter days, the sap underneath the thin, sunbaked bark warms up, then freezes as temperatures suddenly drop at night. This causes ugly cracking which offers an entry for insects and disease. Trees with thick bark are not affected.
What do you do? Protect the trunk with tree wrap, which can be pulled taut against the trunks of both small and large trees. Unlike plastic spiral tree guards, there are no gaps in which insects can hide. Start 1 inch below ground and proceed to the lowest branches. Wrap tightly and overlap each layer of paper by about half. Fasten with duct tape. Be sure to remove in spring to allow for renewed growth.