Disease on Purple Smoke Bush

Hello, I have a Cotinus coggygria 'royal purple', that has been in place for three years now. I am always excited to see what it will do each year but instead of the wonderful display I was expecting I found that its leaves were withering, appearing scorched at the end, and growth was slow. This was all over the plant. On cutting back I found the centre of each stem to have a yellow fur surrounding the core. I do not know if this is part of the plant's normal biology or if I have found a fungal disease. I have attached pictures of the diseased foliage, and the cross section of the stem. Any help in identifying this would be greatly appreciated.View attachment 2060

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That's a really sad looking plant Kwib.
Maybe if we knew where you were it would help.

 

Of course, sorry. In Surrey in the south of England.