Black trunk on Japanese maple

[Steven1969s]

Hello everyone. A few weeks ago my Japanese maple suffered some spring frost and most new growth wilted. I thought I cut out all the damaged branches that started turning black. Today I noticed part of the upper trunk turning a dark color.
What do you guys think this is?

 

[Paradox]

Could be Verticillum, which isnt good.

https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5347330.pdf

Verticillium Wilt

Verticillium wilt is caused by Verticillium dahliae and V. albo-atrum. However, V. dahliae is responsible for the majority of infections on woody ornamentals in southern New England. Hosts Various trees and shrubs are susceptible to Verticillium wilt in the region. The most common hosts in...

ag.umass.edu

Verticillium Wilt of Shade Trees

Information on verticillium wilt of shade trees and how to manage it from USU Extension and Utah Pests.

utahpests.usu.edu

 

[sorce]

What do you guys think this is?

A good reason to grow elms.

Sorce

 

[just.wing.it]

What do you guys think this is?

Its the reason I'm DONE with J Maples!!!
The few I've had all did this.....maybe systemic fungicide may work....but I dont know how people keep up with all those chemicals. I try to limit my chem usage.

And its like, one day everything is fine and pretty, then you blink once and it's black.

Paradox is probably right.....

 

[Dav4]

Let it grow. It could be any number of things including frost damage, trauma, pathogens like Pseudomonas syringae. Black bark usually means dead/dying cambium. If the blackened portion of trunk remains localized/doesn't spread, you're good. If it starts to spread, take another picture to show... I'd be inclined to cut back to healthy tissue at that point, removing any discolored trunk and branching... but take a picture first!

 

[bwaynef]

Could be Verticillum, which isnt good.

Verticilium doesn't present as black on the trunk. Cutting a branch shows dark veins in the cambium, but there aren't black spots on the bark.

If its fungal, at this time of year, its usually Pseudomonas.

If this tree had frost damage, that could explain the black on the trunk. As mentioned, black means its dead (whatever portion is black). You can prune below and make the best of what's left ...after cleaning your tools.

 

[AlainK]

bwaynef is right.

This doesn't look like verticillium, more like pseudomonas, although it's always very difficult to make a definite diagnosis.

One option would be to remove the affected part a bit lower, where the bark looks green, use copper sulfate on the cut and use sealant.