Have you ever seen split bark on a young tree? Or maybe dead wood along the trunk of a young tree? This is likely sunscald. Honey locusts, fruit trees, ashes, oaks, maples, lindens and willows and other thin-barked trees are most commonly affected. Trees that have bark growth lower on the trunk are not susceptible.
Sunscald normally develops on the south or southwest side of the tree. There are two types of sunscald; summer sunscald and winter sunscald.
Summer sunscald is caused by the bark reaching temperatures during the heat of summer that kills underlying tissues. This is more of a problem in states that are more southern including Kansas.
Winter sunscald occurs during late winter. Sunny, warm winter days may heat the bark to relatively high temperatures. Research done in Georgia has shown that the southwest side of the trunk of a peach tree can be 40 degrees warmer than shaded bark. This warming action can cause a loss of cold hardiness of the bark tissue resulting in cells becoming active. These cells then become susceptible to lethal freezing when the temperature drops at night. The damaged bark tissue becomes sunken and discolored in late spring. Damaged bark will eventually crack and slough off.
Prevention is the best way to deal with sunscald. Applying light-colored plastic or paper tree wrap from the ground to the start of the first branches is recommended to protect recently planted, thin-barked trees. Usually protecting the tree the year of planting is sufficient but some trees may need to be wrapped a second year. In such cases, check the wrap after the first year and replace if it deteriorates or becomes too tight on the trunk.
Do not cover the damaged area with wound dressings as these do not help and may delay the formation of callus tissue. Callus tissue will move in from both edges of the wound and will eventually cover the wound.
