Japanese Maples: Black Bark - Fungal Infection or Dieback

Hello everybody,

over the past few years I observed sometimes black coloring of bark of Japanese maples. I ask myself if that’s always a fungal infection, or if dieback, caused by wrong cuts etc also takes on this black color?
What are your experiences?

Here are some pictures…



Hi Max,
This could very well be Verticillium wilt.

1 Like

Heliostar, thanks a lot for the link!


Here is another example…

I tried to bend the lower part of the trunk and wired a new leader in autumn…

Buds did not open this spring. As I removed the clamp I recognised that the bark turned black at the points of contact. Pressure too high on the bark, I think. Below the wire there is also a black area.

The roots looked good to me. I have no idea why this tree died. Maybe the bend was too heavy? I did the same clamp bending with another young maple. Same blackening of contact points. But he is doing well.

My Corel bark did something similar over the winter. I attempted to use snow as an insulator in the early winter. It got to -5f in December. The snow was against the trunk. It was there where the black appeared. Right now there is back budding below the black, and death above. I’m going to wait to trunk chop it until I’m positive I know what died.

Kind of bummed. Maybe it will be a good shohin, since the trunk us only 4" tall now.

I wonder if your bend stressed the cambium layer.

Sad. Did you replace the tree?

Hi Kurt,

the maple in the colander did not make it, also the one in the ground.
The one in the first picture is healthy. I put him in the ground this spring.


I think you’ll find it is Pseudomonas syringae which is often mistaken for verticllium wilt. It can be controlled. Michael Hagedorn has written an article about it. This is the page (not very good at copying links!!!).
https://crataegus.com/2011/11/29/read- this-if-you-grow-japanese-maple

Fixed link:

Thank you @Michael_P. That makes it easier for everybody…