On 24/01/2014 15:35, Nick Maclaren wrote:
I have a long-established Cotinus coggyria that has started to
suffer from a very weird dieback. This affects some branches
(but only some of the shoots on them) and some stray shoots.
I tried cutting it back beyond the affected parts, but with
little effect.

http://i41.tinypic.com/15ckn7q.jpg
http://i43.tinypic.com/15s81g1.jpg
http://i40.tinypic.com/2i1msmd.jpg
http://i42.tinypic.com/b9br41.jpg

It is over 30 years old, and I think that it has been suffering
from the last few years' wetness. My inclination is to cut it
back hard, to neaten it up, and otherwise see what happens. But
it's annoying, as it is unsightly when it happens, which is usually
sometime in mid-summer.

Any ideas of what is going on?

Regards,
Nick Maclaren.




I would hazard a fairly intelligent guess at Phytophthora. It seems to
be made worse by winter wet, but presents symptoms in summer. I lost a
Cryptomeria to it.

You might as well follow your instincts and cut it back, but I doubt it
will recover well given that the roots will be affected. If it is
precious, you could try deeply spiking the ground locally to improve
drainage/compaction, then using something like Rootgrow to encourage
root recovery. However, I think that will probably just be a stay of
execution rather than a miracle cure.

Wish it were better news :~(.

--
Spider.
On high ground in SE London
gardening on heavy clay