Mites could cause the browning, a fungal blight of the needles or twigs, or a root rot.
Mites are almost always a summer problem. They love hot, dry weather. You can find them by placing a white paper beneath a branch that is starting to brown and thumping the branch with the other hand. Then examine the paper. The mites will appear as reddish specks the size of pepper flecks that move around.
Root rots are usually brought on by soggy soil conditions. Avoid overwatering and redirect any roof drainage that might be contributing to waterlogged soil.
Foliar blights are usually caused by fungi. They love wet, humid conditions. Prune away dead branches and twigs and spray with an approved fungicide to stop the infection. Since the damage is occuring from the bottom of the plants, my best guess is that fungal blights are the cause.
Thanks for the question. Please stop in again soon!
Q&A Library Searching Tips