It sounds like you have one of two possible insect pests--pine needle scale or wooly aphids. Scale insects look like smooth white bumps along the pine needles. Wooly aphids are cottony white masses at the bases of the needles and along the branches. If you'd like, take a branch into a local garden center with a Certified Nursery Professional on staff for diagnosis. Treatment for these two pests is similar. For scale, spray with lime sulphur in early spring to kill the eggs. For wooly aphids, spray with horticultural oil in spring to smother eggs. The second step is the same for both pests and may not be necessary if the insect populations are under control; spray with an insecticide in late spring.