The 6" pot of gardenias that my grandsons gave me on Mother's Day last year
are ready to be re-potted. However, on the smaller "under" leaves, I have
found them to be completely covered in a black powder! I can rub it off,
but I have no idea what it is--a fungus maybe? If so, what should I use to
get rid of it? The much larger "upper" leaves are not affected. Any
suggestions will be much appreciated.

Linda