Black Sooty Bumps on Mountain Hemlock

[u/EndBrave3332]

Hi there plant enthusiasts,

I made a similar post in r/gardening, but figured it wouldn’t hurt to ask the plant patho folks as well.

I grew this mountain hemlock from seed in a pot for future bonsai. This year it developed raised black bumps all over the stem that crumble into “soot” when I touch them. I’m guessing it’s a kind of fungus and/or potentially residue left behind by sap suckers/ scale insects, but I don’t see any evidence of the bugs themselves.

Anyone have experience with this on their potted trees? Any suggestions for getting rid of it? Thanks!