trunk colour

Hi, I have a japanese maple, Little Princess, and it has a brown spot on it that formed quite rapidly, over the course of a week or so. I didn't work on it for over a year and I see nothing weird on the leaves. Doe anyone know what this might be? Thanks in advance!

Hi all !! I have a liquidamber which I have grow from a tiny sapling. It is about 5 years old now and looks very healthy. However, it is still bright lime green all over including the trunk. I would have thought that the trunk at least should be turning brown by now, not lime green. I have...