Hi,
I live the Nordics and my garden is been plagued with something that you see in the photos. It is on red and black wineberry bushes, the aronia bush, and the apple tree, and in all cases it is slowly drying the branches. I don't know whether the white stuff are the disease itself or the symptom. The only thing that I idntified in the yard is lots of snales, which I'm not sure as being the cause of the plants drying.
Thanks in advance!

I can not assess the health of the plants in these photos but the gray, greenish white stuff looks like lichen. That is harmless to the plants.
A lichen is a symbiotic relationship between a fungus and an algae. They are growing on your bushes just for support. They are not feeding on your plants. I find lichens to be some of the coolest things on Earth.
But from your images I see overgrown plants in need of a good prune. Perhaps they have been neglected for years. Dense and tangled plants could be killing themselves by not allowing for good healthy growth by blocking light penetration.
But they are suffering perhaps but it is not because of the lichens.

Lichens are completely harmless to the host plants and are not a cause for concern. Indeed they are said to be present in clear air conditions. Just leave them alone. I find them fascinating and beautiful and would be lucky to have them.