Tree Bark Problem

Asked April 10, 2013, 10:46 AM EDT

70-ft tall box elder - bark is coming off - more prevalent on south side of tree

Chippewa County Michigan trees and shrubs

1 Response

The Boxelder, formally known as Acer negundo, is in the maple family. The tree is normally between 30 to 50 feet tall, but can reach 70 feet which is exceptional.

If the splits and cracks are longitudinal and develop during the winter it may indicate frost cracks. Winter stem damage is usually labeled as frost cracking, bark splitting, or bark scalding. Most damage occurs when winters are characterized by long periods of snow cover with subsequent increased reflective light. Trees entering winter under water stress are more vulnerable to frost cracking. The warm winter sunlight warms up the southern and southwestern sides of smooth barked trees. The cold night temperatures cool the bark down, and splitting of the bark occurs, which is increasingly probable if the tree is dehydrated.

Making sure trees are well watered entering the winter months helps as a preventative. Once damaged, the injured area can split back open on very cold, winter days. This phenomenon is common and usually does not pose any immediate threat to the tree. Treating the crack with sealants or paints is typically unnecessary and not advised.

Sunscald is another type of damage that can occur on trees as temperatures drop quickly. Much like frost cracks, it appears on the sunny side of the tree where warm bark may cause cells just under the bark to break dormancy that protects them from the cold. Sunset brings a rapid drop in temperatures, killing these normally dormant cells. Young trees with thin bark are more susceptible to sunscald. Damage from sunscald leaves bark with a sunken appearance where cells have died. Red maples along city streets often have small, oval-shaped dead patches on the trunk that eventually callus over as the tree continues to grow. In extreme cases, large areas of tissue can be damaged under the bark and will show up during the growing season as bark cracks and peels away, leaving wood exposed. Honeylocust, maple, apple, and linden trees are commonly damage by sunscald.

See the following links for more information and photos to help identify what happened to your tree: