Cracks in tree bark - Ask Extension
the photos show some cracks that have developed in my European mountain ash over the summer. Do you know what might have caused them and what I can do...
Knowledgebase
Cracks in tree bark #273656
Asked August 28, 2015, 12:56 PM EDT
the photos show some cracks that have developed in my European mountain ash over the summer. Do you know what might have caused them and what I can do about them? The tree was planted about eight years ago. The side of the tree in the photos faces south. Thanks!
Broomfield County Colorado
Expert Response
It looks like your mountain-ash has been injured by the winter sunlight; this is called sunscald. It occurs in winter months when the sun is at a lower angle in the Southern sky. Note that our native aspens have white bark as a means of preventing sunscald. More detail: http://www.ext.colostate.edu/pubs/Garden/02932.html
The affected area bark is all dead; this means that affected area no longer transports water up the stem to leaves and twigs. Note the color difference between healthy live bark (olive-green) and dead, cracking bark (brown/blackened). "roly-polys"and insects like earwigs may congregate under the cracked bark to take advantage of the habitat it affords.
Tar-based "wound sealants" are of no value.
The tree will attempt to "slough off" the old dead bark and make "woundwood" at the interface of dead and live bark; this woundwood will slowly try to cover the exposed wood. You can carefully try to remove loose, unattached dead bark, to expose the wood underneath. Do not rip or try to pull it off, as it may tear into live bark outside the damaged area. If at all possible, cut it out in such a way so that rain or irrigation water does not collect at the bottom of the wound. Then, spray the entire wound area with a fungicide, 3-4X per growing season.
Note too that you have a codominant stem (side branch) that is already developing "included bark" on the right side of photo 3. It should have been removed several years ago.
You may want to have a tree service address these issues.
The affected area bark is all dead; this means that affected area no longer transports water up the stem to leaves and twigs. Note the color difference between healthy live bark (olive-green) and dead, cracking bark (brown/blackened). "roly-polys"and insects like earwigs may congregate under the cracked bark to take advantage of the habitat it affords.
Tar-based "wound sealants" are of no value.
The tree will attempt to "slough off" the old dead bark and make "woundwood" at the interface of dead and live bark; this woundwood will slowly try to cover the exposed wood. You can carefully try to remove loose, unattached dead bark, to expose the wood underneath. Do not rip or try to pull it off, as it may tear into live bark outside the damaged area. If at all possible, cut it out in such a way so that rain or irrigation water does not collect at the bottom of the wound. Then, spray the entire wound area with a fungicide, 3-4X per growing season.
Note too that you have a codominant stem (side branch) that is already developing "included bark" on the right side of photo 3. It should have been removed several years ago.
You may want to have a tree service address these issues.
