The cedar hedge in my yard is dying and I'm not sure why. I have attached a picture which shows the hedge. The brown trees died last fall and the lighter brown ones have just recently died. I have had the soil tested and it shows to be in good condition. I have checked for spider mites but there don't appear to be any. I have checked the base of the trees and there don't appear to be any holes or any obvious issues. These trees have been fine for at least 6 years prior to dying and my neighbours trees are all fine. I want to replace the dead trees but would like to know why these ones died so that the new ones don't just die as well. Any advice is very much appreciated. Thanks!!!
They're arborvitae (Thuja), not cedars (Cedrus). I'd suspect a fungal root disease, maybe Phytophthora, maybe Armillaria - you'd probably need microscopic examination of root samples to tell. If that is the case, quite likely that any replacements would also die, unless you use something different that resists whichever fungus it is.
Thank you so much for your response Michael and the correction on the species. I will look into having the roots examined. Much appreciated!
Much-planted Thuja occidentalis 'Smaragd'. More prone to root rot than others, photos and questions such as yours posted repeatedly. Grass looks lush, as though ground is on damp side.
Yes, I live in a damp climate, however the first batch of trees died last fall after a dry summer. My first thought was that they may have died from lack of water over the summer, but then the ones that have recently died have definitely had lots of water. Can root rot be caused by over saturated roots or is it always a result of fungus?
I have now dug up all of the roots and noticed on a few of them that there were clear mole holes. Could the mole be the cause of the death of these trees?
Very unlikely - moles are just hunting earthworms, and don't disturb roots significantly. They're actually beneficial in improving drainage and soil aeration.
