Treating pine tree
The gray material on the branches of the spruce tree are lichens. Lichens are unusual organisms. They consist of two unrelated organisms, an alga and a fungus. These two components exist together and behave as a single organism. The agla provides food via photosynthesis. The fungus obtains water and minerals for itself and the alga. Lichens do not harm trees. Nothing needs to be done.
See the following website for additional information on lichens.