Probably winter damage.

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.

Combined experiences reported on the web are pointing already to this cultivar effectively being a mutt, due to the tip die-back.

I'm going to pull mine out, which has had dead ends since the first winter.

This post was edited by bboy on Tue, Mar 25, 14 at 14:22

Pseudomonas infections often follow minor cold damage.

HAD one. "HAD" being the key word. Appears to be a beautiful but VERY weak cultivar. Took exactly two winters (mild at that) to die even with protection. Will not touch this one again.

Arktrees

My bihou did the same thing the first few winters, and even does so a little bit now. I don't know if I needed to do so, but I clipped off the ends. For me, it is a fabulous tree, lighting up the winter landscape, growing faster than other japanese maples, and having great fall color.

Like other colored bark JM's, very susceptible to Psuedomonas. Has proven to be a weak grower.

You may have just been very lucky with yours......good for you :-))

Thanks, I've been unlucky with some others so I hope the luck persists with the Bihou.