its hard to come to any conclusions WITHOUT A PIC ... a 10 foot transplant took huge stresses in the digging .. moving.. and planting ... winter was probably minor after all that ... [and even worse.. if it was grown to 10 foot in a pot] i hope you have PERFECTED WATERING ... see link for a discussion after reading such.. if you want to discuss/compare how you are doing it.. feel free ... ken Here is a link that might be useful: link

That's Bihou (not Bijou) and it could very well be winter dieback. But this cultivar is also extremely prone to Pseudomonas, which often presents as black twigs and stem tips. Sometimes pruning this out to clean wood will help but not always. Pseudomonas can become systemic in time and then untreatable. Eventually the tree will die. If pruning, be sure to sterilize pruners between cuts to limit any potential for spreading diseases.

Here's another (and simpler) possibility. If the JM is goes for several weeks w/o water during the hottest part of the summer, it may respond by selectively letting some (or most, depending on the drought severity) branches die. This may not become apparent until the following spring, when the affected branches will not leaf out. Although lack of water is the "root cause", it might result in various proliferation of various infections, e.g. verticillium, that may be present in the weakened, dying and eventually dead branch. There's no way to know if this is the explanation in your case, but if your tree went without water for more than a week in July or August, I'd suspect something along these lines.

Different situations between achilleas post and Brians :-) As Al indicates, achilleas is an indication of graft failure, not a necessarily uncommon situation with JM's, depending on grower. I would certainly consider keeping the tree (after removing the dead top growth). And following Al's instructions....unless you wish to grow your tree as a shrub, in which case you can just leave it be. Brian, your description sounds very much like one of the fungal pathogens that can affect JM's. Unfortunately, unlike a graft failure, they tend much more likely to be fatal, often in the same season but surely within one or two growing seasons. And your instincts may be right on as far as avoiding JM's in that area -- with several of the pathogens, replanting in the affected area will just continue the problem. It is best to select a more disease resistant species.