Hello all, Would very much appreciate to get some advice on this maple that I received as a present so would like to do my best to save it. It has been dying gradually from top down with these growing black spots on the bark ever since I received it a few weeks ago. I have already cut dead parts several times. Also, the trunk in the last few days has gone from green to red. When I received the plant, it was in a plastic bag with the roots wrapped in wet paper and no soil. The question is whether the plant is best kept as it is or should I make whatever amateur attempt to graft the good part of the branch (i.e. if the roots are the problem). Would appreciate any advice.
Sorry to say, your tree is a goner. The latest color change in the bark on the trunk from green to red has fully guaranteed this - like the leaves changing color in the fall prior to dying, this is what is happening with the trunk. The black spots you've seen on the tree are pseudomonas, a bacterial infection that is spread through water and infects the vascular system of the tree, essentially plugging it up. The only treatment, and even then it may or may not work, is using a copper-based solution; unfortunately, younger/smaller and/or stressed trees are much more susceptible to this pathogen, and much less able to fight it. When you have been pruning off the affected parts of the tree, have you sterilized your pruning shears? If you do not do this, you can spread the pathogen to other parts of the tree (if they weren't already infected) or to other trees. When pruning a possibly sick tree (bacteria, fungus, etc), ALWAYS sterilize after EVERY cut to be on the safe side. Throw out all the soil that the tree was planted in, and if you wish to keep the pot, thoroughly disinfect it before using it for any other trees. Sorry to be the bearer of bad news :(