In the fall season, evergreen trees will shed inner needles. This is a very normal thing that happens. The longer needled evergreen trees such as the White Pine, Austrian Pine, and Norway Pine drop or shed about one-third of their needles each fall.
Because these trees tend to be a more open or less dense tree, it is more obvious on those evergreens. The Spruce also shed needles to a lesser degree, but is less noticeable.
The best way to keep your evergreen trees healthy & looking good is to make sure they are watered enough the entire Spring & Summer. Fertilizing with a soil acidifier up until mid July.