Dothistroma is a needle disease that causes dark green to brown banding on the needles and browning of the needles from the banded area outward . As a result you wind up with needles that are half to three-quarters brown from the tip inward. There should also be discrete spots present on the needles. It is easy to confuse this disease with winter injury so bear in mind when the damage appears and use a hand lens to look for dark structures erupting through the epidermis of the needles in association with the spots and bands, especially near lower end of the dead area. Most infections occur during wet periods in the mid-summer.
Young needles are immune to infection, but they become susceptible to infection after a month or so.
Dothistroma blight can be treated with fungicides, but the timing is different than would normally be used with spruce needle casts. Apply a protectant fungicide such as chlorothalonil, Bordeaux mixture or choose from several copper fungicides that are labeled. Spray in the spring before bud break to protect the older needles and a second time in the mid summer to protect the new needles. The first application is to protect older needles. The second application protects the new growth.