I've recently discovered these orange patches on the trunk of what I believe to be a satomi dogwood. The tree was already here when I moved in 14 years ago and has always been healthy and flourishing.
I was looking at Cryptodiaporthe corni also. https://hort.extension.wisc.edu/articles/golden-canker-cryptodiaporthe-canker/ Initial symptoms of golden canker include wilting and death of leaves on infected branches, followed by branch dieback. Infected branch tissue turns a bright, golden-yellow color. Often, orange spots will be visible scattered over this yellow tissue. These spots are fruiting bodies (reproductive structures) of the fungus that causes the disease. If unchecked, golden canker can spread from infected branches to the main trunk, resulting in the death of the tree above the point of trunk infection.
Thank you both for your input. I'm very sad about this and am consulting an arborist. It's my favorite tree and is stunning - the kind people stop and take pictures of.
I haven't seen such an old dogwood. It seems, that old dogwoods tend to have patchy bark, like this: Satomi_Dogwood_bark_1_web.jpg (600×713) Only the yellow color makes me little bit worried.
Great news! The orange patches are simply an attractive feature of this tree in that, with age, the bark exfoliates to reveal other colours.
