I have been having needle problems on a mountain hemlock for about 3 years, each year it becomes a little worse. The effected foliage is on the north side of the tree and the needles are very dark almost black colour, the new growth is very weak. I have been spraying with a copper fungicide but it has had no affect. The tree is about 12 ft tall and gets full sun. If anyone has any knowledge of this disease I would appreciate any help. Thank you.