I have two pear trees (not the fruit kind) and one dying (I think) maple. All three trees where planted on top of a clay area. Some dirt was brought in at the time of planting, but not enough. A greenish mold grows and then the bark starts to split. This is over some time, of course. What can I do to stop this? The two pear trees are newer, and I replaced the dying maple that was there. Don't want the same thing to start with them. I live in Michigan.
Certified GKH Gardening Expert
The greenish mold, which is lichen, and the cracking are actually not directly related. Lichen tends to attach to stressed trees, so really the lichen appears because of teh cracking.
This kind of cracking can be caused by a few things. I suspect, because these are younger trees, that this is sunscald. This article will help you: https://www.colostate.edu/Dept/CoopExt/4dmg/Trees/sunscald.htm