dead clematis

this year my 12 ft clematis has failed to sprout green leaves,it looks dead,so i have just dug up the ground below it, and found loads of grey ash coloured fungi/mould all over the roots.is this normal,is it rot.if i dig it out is the soil ruined,if i put a new clematis in would that get contaminated by the old plant,thanks for any help.

 

Sounds like it could be root aphids, have a closer look at the material if it moves it`s aphids. The other thing it could be is some type of grey mould. I think, though, it`s more likely to be aphids.