Help save my White Pine
I cannot diagnose this from pictures. I would suggest getting a certified arborists out to look at it. It could be related to water pooling at this spot, it could be an insect problem like a root collar weevil, stem borers, or even some sort of restriction to the stem or roots. White pine do best in well draining soils. You need an expert that can look closely at these plants and may need to dig around the stem of the plant to see what is going on. Certified arborists can be found through their professional association at: https://www.asm-isa.org/ Look under the heading of "Resources".