I'ts a Wrap
Wrapping the trunks of young, thin-barked trees in the winter months is recommended to protect them from frost cracking. Frost cracks are vertical cracks in the bark of trees. They commonly occur on the south and west sides of young trees that haven’t developed a thick layer of bark. On sunny winter days, the cells of the bark and phloem warm up and expand. As temperatures fall in the evening, the bark cools and contracts quicker than the phloem which can cause the bark to rupture. The resulting wound can allow disease causing agents to enter the tree. Wrapping the trunk reduces the rapid heating and cooling and minimizes the incidence of frost cracking.