Pine tree turning white
It looks like the tree may have pine bark adelgid which produce white wooly coating that you are seeing. Below is a link to an article that will provide you with more info on this insect and it's life cycle.
You may want to consider contacting a certified arborist who could look closely at the tree to confirm this and then as applicable, offer a treatment plan. Find a certified arborist via the link below. https://www.treesaregood.org/findanarborist/findanarborist
Hope that helps!