A gray-blue coating appeared on the spruce trees, what is it and how to deal with it. Photo attached.
Unfortunately, there is no closer photo of the trunk and branches of the tree to properly consider what kind of plaque it is. But I dare to suggest that this is nothing like Icelandic moss, or lichen, which appear not only on fir trees, but also garden trees and shrubs. The methods of struggle are simple - sometimes it is enough to clean it gently with something like a spatula, and then produce a whitewash of the affected areas. Instead of whitewashing, you can use a solution of copper sulfate - 10 liters. Bucket of water 300-500 grams