Last year, a delivery driver from Wickes stopped his van in a position
where he had to hack off a lump of bark from the rowan tree outside our
house in order to open his van doors. I phoned the council tree
department the same day in case they wanted to come and treat the tree
in some way.

I don't think anyone came out or did anything, but that was early
spring, and the rest of the summer the tree seemed normal.

At the moment, only a small branch the opposite side to the injury has
some green slightly-open buds on it, and the rest still just has the
dark leftovers from last year. The wood on those inactive branches has
a green patina, and up the trunk is what looks like a dusting of white
powder.

Does it sound as though it's had it, or given another year might it
recover?