My five year old cedars have been great up to now but last fall I noticed a section on one tree where the tips started turning brown. It’s now spring and the brown area is getting wider. I’m worried about root rot and it spreading to other cedars. I did fertilize in the fall, could I have overdone it? Do you believe this is root rot? Should I get a replacement cedar?
Thank you for contacting the Toronto Master gardeners regarding your cedar tree.
We receive numerous questions regarding cedars, and browning seems to be a very common problem. Browning can be traced to a variety of causes, including inadequate soil moisture (too much or too little), winter desiccation (water loss from excess wind), and pests (ex. spider mites). Without knowing any details about the growing conditions and site location of your particular cedars, it is difficult to pinpoint the exact cause. However, if you are noticing that the brown area is getting larger, it is highly likely that harsh winter conditions have resulted in desiccation and dieback, which does not spread from one tree to another. To prevent browning in the future you should consider winter protection. For information on how to prepare cedars for winter, please refer to Covering Cedar Hedge posted previously on our website.
In order to prevent root rot, make sure that your trees are planted in an area that receives adequate drainage. If drainage is an issue then replacing the cedar with another of the same kind will lead to the same results.
My suggestion would be to leave the tree and monitor it during the year. I would shake off the excess brown foliage and continue with good maintenance, see Cedar Tree Maintenance. If you are interested in reading additional posts about browning in cedar trees, please refer to this list of archived questions.