Honey Fungus?

I've been finding these thin black roots in the soil wherever I dig. They are flattened and a little wrinkly, flexible have no little rootlets off them. 

Having done a bit of research it appears they may be bootlace strands of honey fungus, called rizomorphs (it means root form). If it is, then this is not good news for any woody and perennial plants as the black bootlace strands are how it spreads from the original host - and they can travel a very long way - up to 30m.

Once infected you have to dig out the whole root structure to begin the process of trying to eradicate it, which is virtually impossible.

Looking round the garden there is one stump which looks like it could be the host. It's now a very well rotted stump of something that was about 30cm diameter trunk. Now very soft and rotten. If we get honey fungus growing the autumn then we'll know for sure.

A look around the garden reveals other woody stemmed stumps, from 30cm down to 5cm. 

More research, observation and removing rizomorphs whether I find them. 

It's a really big job!