Root rot or fungal attack in japanese maple

Hello-
I'm new to the site, but have wanted to join for some time. I have a japanese maple which is losing healthy looking leaves in the middle of July...Some leaves are turning brownish and wilting. I planted it in a large box last year, with poor drainage, I improved the drainage this past spring and the tree has been growing strongly and has looked healthy. I recently pruned it back somewhat heavily, and a few weeks later, it started wilting, new growth is distorted looking, twig dieback, and I think I see what looks like canker spots on branches...These symptoms occurred last year, I think due to the poor drainage of the box, which I fixed this year...and the way it has grown so far this year, has been great, until a few weeks ago. I typically spray Neem oil on all my trees every few weeks, and now I hear it isn't recomended for japanese maples. The reason I was again alerted to this occurring was that the soil seemed to be staying damp for too long...I don't water it until it dries out however...Anyway, I guess I am preparing myself for the loss of this tree, especially if it has canker from what I'm reading online. Any tips would be great. Thank you.

Jonathan

Photos would help: otherwise, it's like looking for advice on an ailment on the net instead of going to see a doctor

The whole tree, and details: leaves, twigs, "cankers"...

Look up Phytophthora wilt. That's what it sounds like to me.

No cure that I've ever heard of.

Sorry.

JimLewis wrote:Look up Phytophthora wilt. That's what it sounds like to me.

No cure that I've ever heard of.

Sorry.

Yep.

I didn't dare to say. Hard times...

Thank you gentlemen for your responses...I am treating the tree with a copper fungicide for anthracnose. I have recently learned that Neem Oil sprays aren't recommended for japanese maples. What would anyone recommend as a general, weekly or monthly spray for sensitive species like the japanese maple?

I forgot to mention...I did send a branch to the chicago botanical garden and they diagnosed the problem...we'll see how this goes...