What You Need To Know About Sunscald Injury And Your Trees

A common misconception among homeowners is that winter weather does not pose any particular problems for the trees in your yard--after all, they reason, evolution has given those trees everything they need to withstand severe weather. Yet this simply isn't the case. Unless adequately protected, young and/or thin-barked trees are at a significant risk of developing what is known as sunscald injury. This article will provide a helpful overview of this problem, as well as what you can do to prevent it. 

The Basics

Sunscald injury is caused by day-to-night changes in temperature during the winter months. Such temperature swings can cause damage to the cells lying just beneath a tree's outer bark. This is especially true for young trees, which have a less developed outer layer of bark, as well as for species with naturally thin bark. The undesirable temperature swing is often exacerbated by the warming effects of the sun. For this reason, it generally tends to afflict trees on their west or south facing sides. Thus, sunscald injury also often goes by the name of southwest winter injury.

Forms Of Damage

The damage caused by sunscald injury is generally easy to notice, since it affects the outer portion of bark. Visual symptoms may include discoloration, cracking bark, lack of bark, dead tissue, and sunken patches resulting from an inability to grow. Fortunately, less severe instances of sunscald injury may heal given enough time. Yet even then it will increase the amount of stress to which the tree is exposed, thus increasing its likelihood of succumbing to diseases and/or insect infestations.

Susceptible Species

As noted above, sunscald injury can affect virtually any species of tree if it is young enough. For that reason, it is important to take measures protect saplings and other young trees in your yard. Species that are vulnerable to sunscald injury even as adults include:

  • ash
  • aspen
  • apple
  • birch
  • cottonwood
  • maple
  • oak
  • peach
  • willow

Generally speaking, evergreens are not as susceptible as deciduous trees, since their year-round foliage helps to prevent direct sunlight falling on the trunk.

Preventative Tips

The good news is that protecting your trees against sunscald injury is fairly simple. The general strategy involves wrapping the tree's trunk--usually with a white tree wrap. This both increases the tree's insulation and prevents direct sunlight from falling on it. As a result, the temperature fluctuation to which the tree is exposed is kept at a minimum. The white color of the wrap also acts to reflect sunlight away from the tree. Contact a tree service for more help caring for your trees.