Root disease in cedars

Asked November 4, 2017, 1:11 PM EDT

Just read your response to question of what was responsible for dying cedar trees. Is there nothing that can be done to save those around the dying tree. We will soon have a gigantic hole where 3 or 4 cedars use to be. Is there nothing that can be done to protect those not yet infected? Thank you.

Clackamas County Oregon trees and shrubs urban forestry

1 Response

First, my answer depends on which "dying cedar" response you are referring to since, unfortunately, there are many and not all the same species of cedar. First and foremost, we have to identify the species of cedar and the disease organism.

If you are referring to Port Orford cedars dying from Phythophthora lateralis (the most common and deadly cedar disease issue in our area), then it is unlikely that you can save and Port Orford cedars adjacent to an infected area. Once this disease is present in a group of trees, effective treatments are very limited. Soil drench fungicides are listed as a possibility. These can be effective in nurseries and perhaps in certain highly contained landscape situations. Soil drench fungicides are unlikely to be effective in wider landscapes and there are environmental impacts to be considered with such treatments.

Removal of infected trees and replacement with non-susceptible plants is generally recommended. For more information see
https://pnwhandbooks.org/plantdisease/host-disease/cedar-port-orford-chamaecyparis-lawsoniana-root-r...