I bought this Sango Kaku last fall from a nursery, and it has some strange things going on with it that I don't know what to make of. It had a lot of leaf scorch when I bought it, but I took this to just be the result of poor care at the nursery. But there are a lot of dead branches, and there are also some black marks on branches. I actually accidentally broke a branch with leaves on it, and it surprised me how easy it broke. When I looked, I noticed it broke at a black part. The dead branches and black marks were present when I bought it, so I'm wondering if it was just cared for poorly. Outside of these issues, the tree actually looks somewhat healthy. It sprouted many leaves this spring and at first glance it appears lush and healthy (in my opinion). It's only when looking closely that I wonder if something is wrong. I have another Sango Kaku about 20 feet from this one. That tree is one of my favorite trees, fully grown, and so if this tree is diseased, I'm wondering if I should remove it to protect the other.
Good evening and welcome to the maples forum. IMO this tree is on it's way out. Can I ask when you cut off branches was there any black or very dark rings on the cross section. If so then this is Verticulum wilt. Tell tell signs are die back which you have. It's due to water etc, etc, being unable to get to the branches, as it blocks the xylem plant tissues. If it is near your other Sango kaku, then I would remove the new tree and burn it. The soil it's in If VW will need removing as much as you can, as Verticulum a fungal disease is spread via soil and enters via the roots. Anyway, do a cut and photograph the cross section for members to see, this will help ID the problem. Just also to mention that the Coral bark maples are prone to die back. Bi hoo is the worse IMO, but Sango kaku can also be susceptible to this.
Thanks for the info. How thick of a branch do I need to cut to get an adequate cross section for diagnosis?
Should be able to see any disease from a pencil thickness or a touch bigger. If you cut just below the die back., that should give you a good look and a close up photo.
I cut a few branches right below the die back. One of them appears to show something, not sure what to make of it. The branch appears half dead, with one half still producing leaves. But the cross section looks discolored on the dead side.
Hmm... It could be a bacterial disease, which is less serioyus than verticillium. After removing the branches that are black all around, treat with a copper-based spray, that could help.
Agree with Alain, it could be a bacterial disease rather then Verticulum looking at your photos. So cut off all the dead, damaged and diseased wood and treat the ends with a copper paste, ie Bordeaux mix. Make sure you clear up all cuttings and dispose or burn. Then it's a matter of waiting. You should be able to see in a few weeks if it has worked or not. If you start getting blackening and die back again, IMO I would remove the tree and dispose.
