Since you have green cambium above the graft, I think all you can do is wait and see. I might give the nursery a heads-up that you are having problems with it. If any more leaves sprout from under the graft, rub them off as well. Keep watering - stick a finger down about 2-3 inches, next to the root ball. If it is dry, water; if still damp, wait and try again in another day or so. Water slowly and deeply - you want the water to soak in to the bottom of the root ball. If you haven't mulched, do so - as wide as you can, at least out 2-3', no deeper than 4", and no mulch in the 2-3" next to the trunk. Is this a weeping cherry or a willow? You say both, so I am not sure. The action to take is the same, but I would worry more about a willow not leafing out, as they are usually so quick to do so.

Peonea05: Can you tell me what other Itoh cultivar may also have this feature? I would love to get something like that. littlebin: Thank you for the comment. What do you mean don't cut it? Should I just leave that stem as it is and not cut it next spring? How about I let it go to seed and see what would seed do? Let me know, since I really want to preserve this feature. I actually have Er Qiao not far from this Bartzella. This year I got five buds, but none opened, which I suspect is caused by the spring freeze damage. Hopefully next year I will be able to have more flowers. Here is another picture of the pink Bartzella

You'd better to post a pic here to help others identify the problem. If I have the same question, I might first try some pesticide, if it won't work in one or two days, trim off all the infected leaves. Keep in mind that peony like relatively dry environment compare with many plants. Tree peony must experience a low temprature jarovization for at least 1 month, so if the temperature in your room is higher than 7 centigrade in the winter, you'd better move it out. Good luck!

I dunno. Bark could be red maple. Something is wrong with the leaf or samara shape I THINK when I zoom in. Then again my red maple's leaves are a bit rounded....Why isn't every other one on the street doing the same? If you cannget one OP, I request a close of of the red leaves or seeds.