Small Indentations of Trunk of Satsuma Mandarin Orange Tree

I noticed small indentations on my Satsuma tree’s trunk. What might be causing them?

Take a close look at the spots on your satsuma mandarin orange (Citrus reticulate) tree.  If they appear flaky and on the surface of the tree trunk, they are lichens. Composed of a fungus and blue-green algae, these organisms do not harm the plant. In fact, they should be left in place because scraping them off can injure the trunk.  Sunken and discolored areas, on the other hand, are cankers. Often caused by disease, this may be the problem. A tell-tail symptom of canker is stunted or misshapen leaves.  Usually the only remedy for a canker on the main trunk is proper care.  A properly cared for tree is often able to live with the problem. If this doesn't work, it will eventually die and need to be replaced.  Consider waiting several years or using an unrelated plant in this location to avoid infection if a disease was the cause of death.  Consult a certified arborist if you think cankers are the problem.

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