AusBonsai

Wondering if anyone might know what is going on with my Japanese Maple.

I've noticed over the last couple of weeks while it is still dormant, that the trunk and branches have been slowly getting darker. I was slightly concerned but I don't have much experience with JM so I just kept an eye on it. I now thought it must be a root/fungal problem so I decided to do an emergency repot to look at the roots. It is in a very gritty well draining mix and has been thriving in it for almost two years.

Upon closer inspection on the root base I noticed these red clusters of what look like eggs? The root ball seems to be full and healthy. Has anyone come across these eggs before? Thank you in advance.

I don't recognise the red eggs but the black sections on branches are a big concern.
There has been lots of debates about what the black is caused by but it is definitely a problem and will kill branches and if it affects the trunk can kill the entire plant. Usually I see it coming from the base of the trunk but this seems to be doing the opposite.
It appears to result from the pot being too wet through cool weather and is more common where pots are on the ground. I've occasionally arrested it by putting the pots up on a well ventilated bench and reducing water to let the soil dry out more.
A fungicide treatment won't hurt and may even help to slow it.
You might even try pruning off any discolored branches before the fungicide treatment but make sure you sanitize the cutters after each cut to prevent further spread.

Good luck

The ''red eggs'' look like fruiting bodies of some kind of fungus. I think you should cut your losses with this one.

Well I've done the best I can at this stage. I got rid of most of the soil, scraped off all the fruiting body, planted back in pumice/lava pinebark mix, pruned off the worst branches and drenched in fungicide. We'll see what happens.

It stays on a mesh bench that has full air circulation and drainage underneath the pot. I never sealed any of the cuts I made in Autumn, could pathogens have gotten in through them maybe?

It's possible for pathogens to get in through cuts above ground. I've always see the black start from ground level and move up so assumed it came through cut roots but some trees that had not been root pruned also got the same problem so I'm not convinced either way.
All I can say is that some that appeared to have signs recovered when I reduced waterlogging.

Good luck with this one.

After much googling and reading, I am fairly sure it is suffering from the fungus that causes nectria canker. The giveaway is the orange/red fruiting bodies that usually appear around early spring as the temperature starts to warm up.

While I’ve done the right things to potentially possibly keep the maple alive, I’m not sure whether I should be. From what I have read there is no cure and the way to deal with it is to remove infected branches and treat with fungicide. however if the main trunk is infected (as mine is) you obviously can’t prune it away and the most feasible option is the destroy it so it won’t spread to other trees.

I don't have any advice to offer, just wondering what happened in the end?
I hope your maple is still with us

Dustbunny wrote: ↑August 28th, 2023, 8:20 pm I don't have any advice to offer, just wondering what happened in the end?
I hope your maple is still with us

Oh nah that maple is long gone. Whatever infected it was pretty terrible. It was too late by the time I noticed it.

Oh I'm sorry to hear that