Coral Bark turning brown

I am new to the Mirai community, and I can’t believe it took me this long to find this group.

I have a Coral Bark Japanese Maple that I purchased in the heat of the summer last year. I repotted it in a combination of pine bark, pumice, and organic soil that wasn’t properly sifted.

It has been in a cold frame for the past 2 months with snow and leaves for insulation. We had temps down to -8 F. Last week I pulled it out of the cold frame to check on it’s well being. There is a brown spot on the trunk, which doesn’t look good at all. I think that it may be caused by a wet and then frozen soil, and a lack of O2 penetrating the soil. There is also some ‘wrinkling’ in the bark higher up in the tree.

I’m afraid that I am about to lose this tree. I think that it is very weak right now. Would this be a situation where an emergency repot is necessary? Since I potted it last summer, I have started switching to a diatomaceous earth, lava, and pine bark soil mix (sifted to 1/4"-1’16").

What would you do to save this tree, if it isn’t too late already?


Did this just start? Observe if it turns black and/or spreads for the next few days. Possible pseudomonas infection, soil looks too dry also.
If it is pseudomonas, chop it off and hope it back buds.
Have you shown this to a master gardener?

If you want to try a repot, use more organic soil, 50-60% (try an azalea mix but take out the big bark pieces and add steer manure), maybe in a fabric pot and keep in a greenhouse with bottom heat. For the 40-50%, akadama, pumice and aquarium gravel or coarse sand. It might need to stay in the green house for a while too. Check the roots first before you proceed to see if the tree is still ok.

Took a closer look. Looks like the bark above the discoloration is starting to shrivel. Maybe chopping the trunk just above the nose under the discoloration, clean and disinfect well then seal. And hope for the best.

Wait for the other members of the forum to give their opinion or show it to a master gardener. I lost a beni tsukasa maple with the same problem. I waited too long to show it to a master gardener. I was too late when j showed it. Did a trunk chop and hoped for the best.

Or soil is too dry. Maples dont like wet feet but do like sweaty feet.

Thanks ThienXiang. I just noticed this happening within the past week. I’ll keep an eye on it and see if it continues to spread. It seems as though the tree above the dark spot is starting to die. Much of last years growth is crispy, and the bigger branches are wrinkly. Down by the graft it looks pretty good.

My grandmother in law is a master gardener. I’ll show it to her today. Like you said, I don’t want to wait too long. And I think I’m approaching the point of no return. I’ll see what she says, and then possibly do a gentle repot, and heating pad for the rest of the winter.

I wanted to dry the soil out some, because it was pretty wet when I checked it. It’s still moist 1 1/2" down.