I have noticed that my old cedar has a very large number of cones
on it this year. Several areas of foliage have
turned reddish brown. This has all appeared in the past month or
less. Some of the other cedars
in this area appear to have these characteristics. Is something different going on this year? I am concerned that there may be a disease that is affecting them?
Is your tree a true cedar (Cedrus) or a species of Thuja? The Thuja plicata (Western red cedar) in my garden also had a huge number of cones this year, and just like yours,
it has some foliage turning reddish brown. This is probably cedar
flagging, as described in this Washington State University Extension
page. Flagging–the browning of older leaves and twigs–is a common occurrence
on western red-cedar and related trees, such as arborvitae. It usually
develops in late summer to early fall. Often, very hot, dry weather,
followed by rain, will stimulate the sudden dropping of this older
foliage.
If the browning were to be widespread, that might be more of a cause for
concern. Additional links:
Cedar Flagging from University of British Columbia Botanical Garden’s online forum.