By Kentishman58
United Kingdom 
Cercis Forest Pansy died
After 2 years good growth our Cercis has suddenly died with no life left in the stems-please see photos. All other plants in same area not affected. Could this be Verticillum Wilt?
2 Jul, 2022
it does look as if it has had some form of fungal infection.
if you want it confirming send some of the infected material to the RHS. they have a dedicated pest and diseases team. they have helped me identify disease in the past.
If you strip the bark off vertically do you have similar brown streaks.
link to RHS re V.wilt.
https://www.rhs.org.uk/disease/verticillium-wilt
3 Jul, 2022