Flagging on arborvitae or western red cedar
Foliage at the base of branches throughout the canopy turns brown, typically during summer or fall. Needles may drop prematurely. Flagging on arborvitae or western red cedar may be caused by several factors, including injury to roots, drought, and hot weather. Trees usually recover in spring.
Protect trees from injury. Avoid disturbing the soil around the roots. Provide adequate irrigation during prolonged drought.