What has killed our clematis?

Hi all, I'm hoping you can help us work out why our clematis has died.
It's an armandii, white flowered, 9 years old, always been healthy and rampant. It flowered this spring as usual, and then started to go brown from the centre outwards. It now looks completely dead.
We can't see any damage to the stem, we don't think it's dried out, it's not wilted at all.
We're keen to replace it quite soon as it has a huge impact on our lovely neighbours - their garden is quite small and this plant extends the whole length of it on the boundary. The clematis is maybe 50 feet from end to end...

We're wondering whether it might regrow? Whether we'd be unwise to plant another nearby? Do we need to be careful disposing of the dead leaves and stems?
Any thoughts or contributions gratefully received...

 

Have you tried scraping a bit of the stem off near the base to see if it's brown or green?

 

Thanks for your reply - it's too thick to do near the base - more trunks than stem! ...but certainly no green in the cambium further up...

 

Maybe root rot? A lot of plants have succumbed this winter/spring. If it is definitely deceased it might be a good idea to plant a replacement in a different spot somewhere along the fence. Over the years I've come to the conclusion that quite a lot of plants suffer from 're-plant' syndrome, probably because they exhaust the soil for their particular requirements. Hopefully you've got the option of doing that rather than replacing soil where it is/was?

 

As well as root rot @noisette47 mentions, as your leaves have turned brown it might be this - ?

"Clematis wilt disease causes clematis plants to wilt rapidly – in a matter of hours. The leaves and leaf stalks turning black (not brown) is the main symptom. When the leaves turn brown, this is more characteristic of clematis powdery mildew disease or physical damage to the stems."

Depending on the actual cause, cutting it back to the base it may regrow but will take some years to cover such a large area.

As for replanting , from digging up a 5 year old clematis last year we were surpised how big its roots were and how far they had spread, so expect yours will have covered many square yards, so a new plant would be best as far away as possible as you could not readily replace the soil around your existing one.

 

Clematis can be Lazarus plants. I've had more than one that reappeared many years after 'death'. Don't dig it out. You never know.

 

Thanks - I'm pretty confident it's not powdery mildew, though I'll have a look into it....

I'm inclined to leave the roots in for now, in case of a miracle...

 

Thanks - yes - no harm in seeing what happens - there is space elsewhere on the fence line to plant a replacement of some kind...

 

I don't think C. armandii is prone to wilt, and it doesn't look right for that. The stems go black, and you get black, not brown, blotchy marking on foliage too.
It could be slugs/snails grazing on the stems, but that may be less likely too, as it tends to happen on types that are cut back in spring and then produce their new stems for that season. I have plenty that are like that this year - much worse than usual. It would be tricky to get in and see where there could be munched growth though, because of the other planting.
Armandiis don't do well round here - climate isn't very well suited to them, so it's possible the root system is failing due to excess moisture, although that ivy would likely be soaking up a fair bit.
The ivy may be causing some problems too if it's strangling any viable stems.

It might be a case of cutting everything right back - ivy as well, and then waiting to see what happens.