Here, from northscaping.com, is a good description of winter burn and how to prevent it, which I wish I had read and absorbed in time to save this little tree. Sufficient watering in the fall and protection from drying winds and high sun while the ground was still frozen would have helped considerably. I've seen burlapped shrubs in local yards from time to time; now I know why.
This winter damage to evergreens is caused by a combination of winter sun and persistent cold, drying winds, which both draw upon the reserves of moisture in the needles. If the ground is still frozen and the plant cannot replenish this lost moisture, the result is death of the green tissues, and loss of the needles.The photo above and other examples of winter burn can be found at the Purdue Plant & Pest Diagnostic Laboratory's website.
Winterburn doesn’t occur on the coldest days of winter, but rather in early spring, when the sun is already high in the sky, but the ground is still frozen. It tends to be most severe in years when snow lingers into March and April, reflecting the light of the sun up into the branches. The problem is made much worse when evergreens are planted along the south or west side of a white house, which reflects the sunlight onto the back of these plants, burning them from both sides.
There are a number of ways to prevent winterburn damage to evergreens. First, be sure to choose evergreens that are resistant to windburn and are adequately hardy for your area. Secondly, never plant evergreens right along side the south or west wall of a white house, unless you are in a really warm part of the North. Thirdly, plant tender evergreens in a location with some protection from winter winds. Finally, be sure to give your evergreens a good watering just before freeze-up in fall, to boost their moisture reserves. Other than these practices, a protective burlap shield supported on the south and west side of the evergreen by wooden or metal posts will block both the sun and the wind, and increase the plant’s chances of successfully making it through the early spring.