How can I rescue my arborvitae?
I live near Nashville, TN & have four 5-6 y.o. arborvitaes, 6-9 ft tall. Recently, I've noticed the interior foliage on my trees has turned brown & died. The exterior foliage (sunlit part) on all four is still green. Is this normal? My neighbor's 20 ft arborvitae looks like it has the same problem.