Sunscald affects young trees with thin, smooth bark. It is most common in late winter on the southwest side of the trunk. Exposure to sunlight and warm temperatures during the day heats up the tissues causing them to lose their dormancy. After sunset, when the temperature drops, these cells freeze and die. The result is large, irregular, wounded sections of the bark on this side of the trunk.
Frost cracks are long splits in the trunk or stems. They are caused by old wounds and drastic changes in temperature heating and cooling the outer and inner layers of bark at different rates.
Tree wraps can be used during the winter to protect young trees from weather-related injury. Wraps can be purchased for this purpose and should be light-colored with some elasticity. The trunk should be wrapped starting at the base of the tree upward and stopping just below the lowest branches. This is only seasonal protection for trees during their first few years of establishment. Remove the wrap in the spring and never staple the wrap onto the trunk.
Cynthia Domenghini, Kansas State University Instructor & Horticulture Extension Specialist