I have several aprox. 60 yr. old cedars around our house on a 1/2 acre in Langley. All are very healthy except one in our front yard. It is the same height and diameter as the other trees, but the foliage is not as healthy in appearance and is much thinner and thinning more each year. The soil is sand and gravel with a good rich top layer of dark soil and composted bark mulch. It is watered with our sprinkler system and all the native plants growing beneath it are doing very well. What may be the possible causes and what can I do to save the tree? Who would be a good person to call for help?
Western red cedars locally can exhibit signs of drought stress. especially towards the end of our summer. They get thin, scraggly, off color and at the worst, die back from the top of the canopy in addition to the reasonably expected flagging (interior growth turning brown in random areas). Whats your watering system schedule like? frequency? duration? actual amount of water put down during a cycle? test by putting a bunch of plastic cups around the zone and running the water cycle, you might be surprised at how much or little water gets to some places.
Is it shaded by the other trees so it gets less sun? Have you closely examined the foliage for insects?
The cedars both have equal light and I have not seen any obvious signs of insects. Would they be in the bark or foliage?
if you want to check for insects, a good basic way is to take a sheet of white paper out of your computer printer, hold it out under the foliage and tap tap the foliage firmly. See what lands on the paper. if there is a bunch of anything in particular, ID it and you may have the culprit.
Thuja plicata is remarably resistant to pests and diseases. However, commercial growers do sometimes have to control for mites usually found inside the tree rather then on the outter tipstoward the tree base, usually found inside the tree rather then on the outter tips. The most serious disease in BC is Keithia blight, a fungus, that usually presents as browning on some branch tips. See: http://www.pfc.cfs.nrcan.gc.ca/diseases/nursery/pests/dthujina_e.html#Figure126 Neither mites nor blight are likely to present as wilting branches, however.So it seems more likely that your tree is suffering from root problems or interior trunk rot. T.plicata is a mainstay of the forest industry and has been extensively studied. You may find a diagnoses at the following: http://www.pfc.cfs.nrcan.gc.ca/diseases/hforest/diagnose/SignHost/tplicata_e.html
