We live in Vienna, Austria, very near the Danube. We planted this Japanese Maple in the first year after moving in the spring of 2013. It has been slow but steady growing, improving a bit every year. After five years, it really started looking like a nice bush, when the leaves started curling and dying. It has one branch that produces no new growth, the rest seems to be still growing new leaves, but the existing ones seem to dry up very quickly and fall off. I don't know enough about the tree to figure out if this is normal or not or where the problem might be. I hope the pictures will help, because other than the images, I can't provide much more information. We have not done anything different with the tree this year that would cause this strange behavior.
Please tell more about the weather of the past few weeks. Was is hot? Dry? Sunny? How much sunlight does your maple get? These Acer palmatum trees grow best in half shade. The dry leaves do suggest heat and drought.– bennAug 28, 2018 at 10:31
I don't know enough to comment on the possible diseases affecting the tree but I think this has been a difficult year for Japanese maples in many places because of the hot and dry summer many of us are experiencing. Where I live in the Pacific North West all the Japanese maples look stressed to me. Yours certainly looks stressed as well. Make sure it gets lot of water. That might help it.– Al MakiAug 28, 2018 at 15:51
It is very odd that you should have two trees with a problem with unexplained die back, the apricot mentioned in this question and also this one. Once you are convinced one or the other needs removal, or even in a non-planted location, it would be helpful to dig down about a half metre and see what kind of soil you have underneath the immediate topsoil. Check with your local utility companies first, though, they can get very irate if people cut gas lines or fibre optic cables.
It's true, though the damage to the Japanese Maple is much smaller than the apricot tree. Japanese Maple is in the front yard, while apricot is in the back yard (at least 20 m difference between them) and there are several trees and shrubs between the two that have no issues (unless the roots of other trees do not reach as deep). The lot had debris of old buildings destroyed during the World War II, but I hope there would be no poisonous materials. I don't remember any pruning of the maple, but would it be able to spread via pruning tools? Aug 28, 2018 at 9:48
This is helpful extra information that I think readers will appreciate in the original post. If it is soil quality and definitely not canker on the apricot, then tools will have little to do with the issue. Aug 28, 2018 at 9:54
I'm sorry to say it's probably not good news again. Japanese Acers are particularly vulnerable to verticillium wilt, again caused by a fungal infection, though it's not the same as the fungal infection on your apricot tree. The likely culprit in this case is verticillium dahliae, commonly known as die back; it is extremely common for dieback to occur in Acer palmatum varieties, and I'm afraid there is no effective treatment https://www.rhs.org.uk/advice/profile?pid=255
Verticillium dahliae resides in the soil, so it's best not to plant another Acer in the same position, nor to transfer any of the soil around its roots to anywhere else in the garden. In the meantime, you can prune back dead branches - it may still produce growth next year, but will likely eventually give up and die altogether, at which point it should be removed.
I'm very sorry to have to have given such bad news in regard to both your questions. It's probably best to choose different replacement plants which are not particularly susceptible to fungal infections.
First thing is to rake up all that debris and get it away from the 'graft'. Those green leaves are growing from below the graft from the root stock, I think.
Take a good pair of by pass pruners and cut off without leaving stumps all little thin branches that grow towards the center as well as are in the center of this tree.
What are your maintenance practices? Fertilizer? Needs a bit of balanced fertilizer if you've never added a balanced fertilizer.
Don't tie up limbs as you've done. Makes weak branches and branching angles. Better is to head back that limb taking the weight off the end of the branch. Cut back to a bud growing upwards and outwards.
Please pull the debris back, the chips included and take a picture of the trunk and soil connection. And graft.