Hello,

The damage to your evergreen tree appears to be environmental and does not look like it was caused by insects or a disease. Some questions to ponder are:
How far away from the road or driveway is the damaged side of the tree?
Does the snow plow or snow blower toss salted snow onto the branches in the damaged area?
Did any area beneath the tree get treated with an herbicide such as a weed and feed product?
Was there any construction in the immediate area that would have affected the tree or roots of the tree?
Was there a campfire nearby that burned the tree?
Was a vehicle parked close by that emitted fumes that would have singed the tree?

Look at the overall area where the tree is located for other clues that could have damaged the tree. You can also send a sample to your local Cooperative Extension System for them to diagnose a brown-going-to-green branch of the tree. Upon further microscopic examination, other causes may be seen more clearly than in the photos.

Regards,
Carol Quish
UConn Home and Garden Education Center