Chances are that it is windburn from the harsh couple of winters we’ve the last two years. The best thing to help them recover would be to feed them by poking holes in the soil below them and pouring Holly-Tone food into the holes. You can also give them a boost with foliar feed by diluting Mir-Acid evergreen food per the directions and pouring it over the plant from a watering can. This foo goes right into the plants needles and stems…like emergency food. Do this once a week until the weather gets hot.
Bring a sample in to the store if so we can determine if it is mites and, if that turns out to be the case, you can spray them with Neem oil to control them.