Hard to say, might be verticillium wilt. If that, nothing can be done. If you can, take several affected branches to your county Ag extension office and they might be able to tell. Below is some info. My pagoda dogwoods get golden canker on some branches, but my oldest ones can carry on w/that issue (I help them by cutting off affected stems).

https://gardenerspath.com/plants/landscape-trees/dogwood-disease/

I changed the title of this post as I was mistaken in the identification. My trees are pagoda dogwoods, not silky.

Also, the ones that died did so over the past winter, very fast. They were fine last summer, no leaf spots nor signs of disease. Weird!

Cornus Alternifolia (Pagoda dogwood).

I planted a seedling two years ago and it grew beautifully that first year (2022).

It came through the next winter fine but as soon as the buds were breaking that spring, the new leaves looked a little weird. It grew for a few weeks with twisted, discolored leaves and then died.

I'm just guessing it was golden canker, a well-known problem along the northern tier states.

https://extension.umn.edu/plant-diseases/golden-canker-pagoda-dogwood

Ah, it looks like Bill is the winner -- golden canker seems to fit. Guess they all are/will be gone.

What a shame.