Evergreen Magnolia leaves turned brown suddenly - Ask Extension
Greetings,
All the leaves on our evergreen magnolia have turned brown suddenly since April. The leaves have not dropped as yet. There is still some g...
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Evergreen Magnolia leaves turned brown suddenly #754316
Asked June 06, 2021, 2:15 PM EDT
Greetings,
All the leaves on our evergreen magnolia have turned brown suddenly since April. The leaves have not dropped as yet. There is still some green on the cambium layer. I also noticed white splotches on the bark. The tree receives regular water from the water system. Could this be frost damage from the snow and ice we had in February? (Other snow and ice in previous years has not caused this problem.) Or perhaps a disease? Will the tree recover or should it be removed?Thanks so much for your help.
Christine Jennings
Washington County Oregon
Expert Response
About this time of year these trees start to defoliate the older leaves as the new ones grow and become established. Although that is a normal response, the entire tree does not brown out like the one in your images.
One image is of the trunk showing nice white, almost circular crustose lichens. They are not a problem and just sit on many different trees. You can read about them here:
https://pnwhandbooks.org/plantdisease/pathogen-articles/nonpathogenic-phenomena/algae-lichens-mosses-plants
That same image might have an insect hole near the top of the image within one of the lichens growth area. Unless you are seeing a lot more I don't think this is an insect problem.
The image of the whole tree shows that all the leaves are indeed brown and dead while other trees and plants and lawn appear to be doing just fine. Sudden collapse of a tree in that hot weather usually indicates a root issue in the absence of other problem along the trunk. The major one we see is called Verticillium wilt. That might be why you sent an image of a stem in cross section. Trees with this disease can show discolored arcs or ring is this tissue but we don't see that in your image. This could still be Vert wilt where the discoloration in the vascular system is lower down in the tree. You can read more about this disease here:
https://pnwhandbooks.org/plantdisease/pathogen-articles/common/fungi/verticillium-wilt-pacific-northwest
I am sorry to say that it looks like the tree is not going to come back. Maybe in the process of removal you might discover other symptoms or signs that point to the cause of its mortality.
One image is of the trunk showing nice white, almost circular crustose lichens. They are not a problem and just sit on many different trees. You can read about them here:
https://pnwhandbooks.org/plantdisease/pathogen-articles/nonpathogenic-phenomena/algae-lichens-mosses-plants
That same image might have an insect hole near the top of the image within one of the lichens growth area. Unless you are seeing a lot more I don't think this is an insect problem.
The image of the whole tree shows that all the leaves are indeed brown and dead while other trees and plants and lawn appear to be doing just fine. Sudden collapse of a tree in that hot weather usually indicates a root issue in the absence of other problem along the trunk. The major one we see is called Verticillium wilt. That might be why you sent an image of a stem in cross section. Trees with this disease can show discolored arcs or ring is this tissue but we don't see that in your image. This could still be Vert wilt where the discoloration in the vascular system is lower down in the tree. You can read more about this disease here:
https://pnwhandbooks.org/plantdisease/pathogen-articles/common/fungi/verticillium-wilt-pacific-northwest
I am sorry to say that it looks like the tree is not going to come back. Maybe in the process of removal you might discover other symptoms or signs that point to the cause of its mortality.
