Some of the pines around minnesota have periodically withered and yellowed. I have noticed this most in the white pines. I think it may have something to do with the chnaging climate. Don't know if ontario is experiencing any of the same patterns but minnesota has definitely been warming.
Heard a story on NPR that the gradual warming will alter our whole tree landscape. Warmer weather means less pine and more poplar and brich around here. Hate to loose those great white pines. Anyone else see effects like this???
The only other thing I would guess in going on with your pine is some sort of fungus... but that is a shot from the hip. Get a closer shot of the needles. Put a couple on a solid surface like a picnic table and take some closer shots in good light.
Hope the tree heals.