Ruh roh. That doesn't look too good. I had a birch tree that looked exactly like that. Eventually the "sick" trunk split and fell over. The rest of the tree had to be removed. Maybe you will be luckier. I'm not an espert in these matters. Good luck.

Try a systemic insecticide. I messed around with the oil to no avail with my birches and scale, I finally used one and it seemed to work. I've heard of neem oil being used as an organic systemic pesticide but don't know where you would find it or how to apply it. If you use the other kind, read the label and see if it applies to scale bugs, and follow the directions.

I lost a newly planted Mountain Ash one particularly wet year and the nurseryman said yes, too wet -they prefer a light, very well drained soil (rocky, or on a slope). Once they are well established, I'm not sure if that's so much an issue unless perhaps it is planted in a consistently wet/compacted spot.

Amester, my yarrow hasn't started blooming yet and I've misplaced the plant identifiers so I'm not sure. It's just been soooo prolific. If it comes out white, I'll know it came from you now. Sounds like Skybird is my columbine donar. I'd love to stop down at your place sometime and see your place and maybe dig up a few starts. With that many bees and butterflies buzzing/fluttering around your place must be surrounded in flowers! That's good to know that the bees love catmint. The patio area I was going to have them, others suggested I use the May Night salvia. I might just try catmint in a more obscure place. I read that butterflies like the salvia, what is your experience? I also read that it likes moist soils (which was why I initially wanted the catmint being more drought tolerant). Again what is your experience? I used to have valerian and loved it but I don't remember having very many butterflies. I wonder why I didn't have that many because I've read that I should have. I took a walk around my neighborhood and noticed most/all of the iris had already bloomed and mine haven't even started. They look extremely healthy so I'm keeping my fingers crossed. I'll give them till next spring.