Cedar trees dying

Asked July 13, 2015, 3:02 PM EDT

I have numerous cedar trees on my property in West Linn, Oregon. 6 mature trees have died over the past 3 years, and another one this summer, costing $$$ in tree removal. Some people have suggested a red ant or a fungus is killing them, or they are the wrong species of cedar for this area. Most of the cedars were planted over 30 years ago, others were volunteer growth. I have seen no ants or unusual growths on the trees. What could be causing them to die? I have many more cedars and wish to protect them. I appreciate your opinions and suggestions.

Clackamas County Oregon forestry tree health

4 Responses

To diagnose the cause of your cedar mortality it is important to identify the species of cedar you have. Do you know which species it is? If it is Port Orford cedar, which was commonly planted in our area, there is a root disease that is quite virulent on this species and often causes rapid decline and death of the whole tree.

I can help you with further investigation. Are you seeing symptoms of decline or dieback in your remaining cedars at this time? Could you send some photographs of your cedars?

Yes, I am seeing some decline in my remaining cedars, starts slowly with lowest limbs, then a sudden dieoff. Last tree died within 2 weeks while I was on vacation.

Hope the attached photos are helpful in identifying the species of cedar. Is there anything I can do with the remaining cedars? They are quite large and require an arborist to take down in sections. I have a designated wildlife habitat -no pesticides.
Thanks for your help.
Marilyn Scott

Sorry about the photo duplication. See attached.

From the photos, it is highly likely that you have Port Orford cedars (Chamaecyparis lawsoniana) infected with the root disease Phytophthora lateralis. Without direct inspection and a sample of the diseased parts this is not 100%, but very likely. Since you have a dead tree that I expect you will have removed, you could hire a certified arborist to do the inspection, confirm the ID, and give you estimates of removal costs. See the International Society of Arboriculture website at http://www.isa-arbor.com/findanarborist/findanarborist.aspx

In general, there is really not much you can do to save Port Orford cedar that has been exposed to (or is next to trees infected with) P. lateralis. You may want to think about suitable replacement trees for the soil and site conditions. P. lateralis does not infect species outside of the genus Chamaecyparis.