Not sure about oily bark- never seen them do that before.

I've always treated my Crepes with foliar feed that had a decent amount of corn meal tea to fight off any mold or ick they ever had- and that's been rare to need it.

Are these trees or shrub-sized?

The dieback was probably because while we overall didn't have the most cold cold of winters, we did have a few days of much much lower temps than is normal around here. I'm thinking of the day in Dec where it was 9 when I got up. That may have done it.

_________________
Shepherd of the Trees
It is not our part to master all the tides of the world, but to do what is in us for the succor of those years wherein we are set, uprooting the evil in the fields we know so that those who live after may have clean earth to till.