In article ,
Jon Nicoll wrote:
I'm trying to determine why our viburnam has died, in somewhat
spectacular fashion

A bracket fungus - my books are a bit inaccessible at present, but something
like dryad's saddle - there are quite a lot, however, and identifying fungi
precisely is seriously tricky. Many of them (probably that one) do not kill
the host and, if it had been a species that is adapted to the loss of its
heartwood(like oak), it would still be fine (but hollowed out, stag-headed
etc.) A large horse chestnut just across the road had been felled because
of a similar issue (but different cause). Suckering trees will respond by
forming a group (or even thicket) of shoots, provided the roots are alive.

The symptoms are wildly unlike either honey fungus or phytophthora, and the
Web and media do us no service by banging on about those. They are just two
examples of many thousands of parasitic fungi and microorganisms that are
common in the UK.


Regards,
Nick Maclaren.

On 04/10/2020 10:22, Nick Maclaren wrote:
In article ,
Jon Nicoll wrote:
I'm trying to determine why our viburnam has died, in somewhat
spectacular fashion

The symptoms are wildly unlike either honey fungus or phytophthora, and the
Web and media do us no service by banging on about those.

I am afraid a comment the OP made - and I missed at first reading -
/does/ suggest Phytophthora. He stated "There are deep cracks running up
one or two the trunks".

In June last year I had a Grevillea rosmarinifolia die within two weeks.
It had been in the ground for six years and had been growing very well,
being about 150 cm high and across. It appeared to die by drying out, as
the flowers and even some of the leaves were shrivelled. Remember that
this is a plant from SE Australia, well used to very hot and dry
conditions. (One I had previously growing at another garden shrugged off
the extreme heat of the "noughties" and grew to 350 x 350 cm. It was
still growing well when we moved.)

The plant I had which died showed one particular condition which puzzled
me, and that was deep longitudinal cracks along its trunks:
https://ibb.co/TH9Nfnh

When I asked about this with someone I know at the Royal Botanic
Gardens, Sydney, he replied:
"... in an Australian context I would put this down to attack by a root
pathogen, and in this country the most likely culprit would be
Phytophthora cinnamomi... In the UK context it could be a different
pathogen of course, but the suddenness of attack and the stem split is
reminiscent of ‘Pc’ as it is often called here. Basically the
pathogen, the spores of which are borne in water and soil, infects the
roots (often at times when the plant is under stress from other causes)
and blocks the water-conducting tissues of the roots, leading to sudden
dehydration, sudden wilting/browning of foliage, and (sometimes) stem
splits as the tissues are denied water"

--

Jeff

On Sunday, October 4, 2020 at 1:29:26 PM UTC+1, Jeff Layman wrote:
On 04/10/2020 10:22, Nick Maclaren wrote:
In article ,
Jon Nicoll wrote:
I'm trying to determine why our viburnam has died, in somewhat
spectacular fashion

The symptoms are wildly unlike either honey fungus or phytophthora, and the
Web and media do us no service by banging on about those.


(Nick) Thanks for the thoughts, but I'm puzzled about your Bracket Fungus idea.
- I can't see any Bracket Fungus (possibility of one tiny bit). The object I
am calling a 'gall' is not a fungus, I am pretty sure. It's quite woody
- From my readig, Bracket fungus lives on dying wood, but doesn't cause the
dying.
Can you explain a bit more? Thanks


I am afraid a comment the OP made - and I missed at first reading -
/does/ suggest Phytophthora. He stated "There are deep cracks running up
one or two the trunks".

I'm not sure how similar the cracks in your photo are to those on my
Viburnam. Unfortunately I can't take any more photos, I've got rid of the tree.
Phytophthora was my initial best guess as well, but would it cause the large-
scale sponginess of the tree and roots I am seeing?

J^n

In June last year I had a Grevillea rosmarinifolia die within two weeks.
It had been in the ground for six years and had been growing very well,
being about 150 cm high and across. It appeared to die by drying out, as
the flowers and even some of the leaves were shrivelled. Remember that
this is a plant from SE Australia, well used to very hot and dry
conditions. (One I had previously growing at another garden shrugged off
the extreme heat of the "noughties" and grew to 350 x 350 cm. It was
still growing well when we moved.)

The plant I had which died showed one particular condition which puzzled
me, and that was deep longitudinal cracks along its trunks:
https://ibb.co/TH9Nfnh

When I asked about this with someone I know at the Royal Botanic
Gardens, Sydney, he replied:
"... in an Australian context I would put this down to attack by a root
pathogen, and in this country the most likely culprit would be
Phytophthora cinnamomi... In the UK context it could be a different
pathogen of course, but the suddenness of attack and the stem split is
reminiscent of ‘Pc’ as it is often called here. Basically the
pathogen, the spores of which are borne in water and soil, infects the
roots (often at times when the plant is under stress from other causes)
and blocks the water-conducting tissues of the roots, leading to sudden
dehydration, sudden wilting/browning of foliage, and (sometimes) stem
splits as the tissues are denied water"

--

Jeff

In article ,
wrote:

(Nick) Thanks for the thoughts, but I'm puzzled about your Bracket Fungus idea.
- I can't see any Bracket Fungus (possibility of one tiny bit). The object I
am calling a 'gall' is not a fungus, I am pretty sure. It's quite woody
- From my readig, Bracket fungus lives on dying wood, but doesn't cause the
dying.
Can you explain a bit more? Thanks

Most bracket fungi ARE woody - you can even use them as fuel. Your
description indicated that the fungus hadn't actually killed the
plant directly - just caused it to fall over - which is very typical
of a heartwood-destroying fungus. As I said, some plants (like oak)
are adapted to such things, and often live longer with no heartwood
left in their trunk than while there still was some.

Fungi like coral fungus live on dead sapwood, but many others (like
at least many bracket fungi) live on heartwood (instead or as well).
The thing to remember is that, in most broad-leaved, non-tropical
woody plants, heartwood IS dead. Most conifers and some tropical
plants are different.


Regards,
Nick Maclaren.

On Sunday, October 4, 2020 at 6:05:49 PM UTC+1, Nick Maclaren wrote:
In article ,
wrote:

(Nick) Thanks for the thoughts, but I'm puzzled about your Bracket Fungus idea.
- I can't see any Bracket Fungus (possibility of one tiny bit). The object I
am calling a 'gall' is not a fungus, I am pretty sure. It's quite woody
- From my readig, Bracket fungus lives on dying wood, but doesn't cause the
dying.
Can you explain a bit more? Thanks

Most bracket fungi ARE woody - you can even use them as fuel. Your
description indicated that the fungus hadn't actually killed the
plant directly - just caused it to fall over - which is very typical
of a heartwood-destroying fungus. As I said, some plants (like oak)
are adapted to such things, and often live longer with no heartwood
left in their trunk than while there still was some.

Fungi like coral fungus live on dead sapwood, but many others (like
at least many bracket fungi) live on heartwood (instead or as well).
The thing to remember is that, in most broad-leaved, non-tropical
woody plants, heartwood IS dead. Most conifers and some tropical
plants are different.


Regards,
Nick Maclaren.

Hi Nick
so you think that the 'gall' I picture in photos #6 and #7 are a
bracket fungus? If so it is the only one.

To expand on my original statement - it looks like it was the sponginess
of the trunks/crown which led to the whole thing toppling down. And yes,
the majority of the leaves seemed fine; similar to those of the newer shoots
you can see coming from the crown.

I suppose it is possible that despite the healthy-looking leaves, the whole
things could have been about to die. would it have been possible for the upper
branches and leaves to have obtained sustenance through the spongy crown,
do you think?

Thanks
J^n

In article ,
wrote:

so you think that the 'gall' I picture in photos #6 and #7 are a
bracket fungus? If so it is the only one.

Yes. That's normal.

To expand on my original statement - it looks like it was the sponginess
of the trunks/crown which led to the whole thing toppling down. And yes,
the majority of the leaves seemed fine; similar to those of the newer shoots
you can see coming from the crown.

Very typical of a heartwood-destroying fungus attack.

I suppose it is possible that despite the healthy-looking leaves, the whole
things could have been about to die. would it have been possible for the upper
branches and leaves to have obtained sustenance through the spongy crown,
do you think?

As Chris says. If you find a completely hollowed-out tree (oak, ash,
willow etc.), you will see how the heartwood merely holds things up,
and it's only the sapwood and cambium layer that transport nutrients.


Regards,
Nick Maclaren.

On Monday, October 5, 2020 at 10:27:17 AM UTC+1, Nick Maclaren wrote:
In article ,
wrote:

so you think that the 'gall' I picture in photos #6 and #7 are a
bracket fungus? If so it is the only one.
Yes. That's normal.

FWIW I took a closer look at the 'gall' and it does seem to be a fungus; I broke off the top
and you can see that is is structured very vertically

To expand on my original statement - it looks like it was the sponginess
of the trunks/crown which led to the whole thing toppling down. And yes,
the majority of the leaves seemed fine; similar to those of the newer shoots
you can see coming from the crown.
Very typical of a heartwood-destroying fungus attack.
I suppose it is possible that despite the healthy-looking leaves, the whole
things could have been about to die. would it have been possible for the upper
branches and leaves to have obtained sustenance through the spongy crown,
do you think?
As Chris says. If you find a completely hollowed-out tree (oak, ash,
willow etc.), you will see how the heartwood merely holds things up,
and it's only the sapwood and cambium layer that transport nutrients.

At the crown there was pretty much no distinction between 'heart' and 'sapwood',
it was all spongy.

So the current idea is that it was some sort of fungal attack, starting at the roots,
with the bracket fungus being later evidence of this?

I guess this means that I should dig out the roots and be careful about what I plant in
its place. Is there anything else I can do to the soil? Should I be worried about
the nearby rose?

Thanks, J^n

On 04/10/2020 16:45, wrote:
On Sunday, October 4, 2020 at 1:29:26 PM UTC+1, Jeff Layman wrote:

I'm not sure how similar the cracks in your photo are to those on my
Viburnam. Unfortunately I can't take any more photos, I've got rid of the tree.
Phytophthora was my initial best guess as well, but would it cause the large-
scale sponginess of the tree and roots I am seeing?

No. The sponginess will be due to a fungus. Also, as Nick has noted, if
the leaves were pretty much untouched, it won't be Phytophthora or
Verticillium.

--

Jeff

In article ,
Jeff Layman wrote:
On 04/10/2020 10:22, Nick Maclaren wrote:
In article ,
Jon Nicoll wrote:
I'm trying to determine why our viburnam has died, in somewhat
spectacular fashion

The symptoms are wildly unlike either honey fungus or phytophthora, and the
Web and media do us no service by banging on about those.

I am afraid a comment the OP made - and I missed at first reading -
/does/ suggest Phytophthora. He stated "There are deep cracks running up
one or two the trunks".

But phytophthora attacks only living tissue, and spongy heartwood
is an almost certain indicator of fungal attack. The vigorous shoot
also argues against phytophthora, because that generally kills first
and subsequent fungal attack destroys the dead plant.

Verticillium and other fungi can also cause deep cracks in bark,
incidentally. I have a Cotinus coggryia with all of its stems down
to the heartwood for half their circumference, and it has been like
that for many years (it's Verticillium).


Regards,
Nick Maclaren.

I have just looked back, and "Most of the leaves were healthy; perhaps
a few have been a bit deformed." is stronger than I remembered, and is
flatly incompatible with Phytophthora (or Verticillium).


Regards,
Nick Maclaren.

On 04/10/2020 17:41, Nick Maclaren wrote:
I have just looked back, and "Most of the leaves were healthy; perhaps
a few have been a bit deformed." is stronger than I remembered, and is
flatly incompatible with Phytophthora (or Verticillium).

Yes, it doesn't look like Phytophthora or Verticlillium if the leaves
are healthy. I agree the spongy heartwood looks like a fungal attack.
Perhaps the plant was infected with more than one pathogen.

--

Jeff

On 04/10/2020 17:38, Nick Maclaren wrote:
In article ,
Jeff Layman wrote:
On 04/10/2020 10:22, Nick Maclaren wrote:
In article ,
Jon Nicoll wrote:
I'm trying to determine why our viburnam has died, in somewhat
spectacular fashion

The symptoms are wildly unlike either honey fungus or phytophthora, and the
Web and media do us no service by banging on about those.

I am afraid a comment the OP made - and I missed at first reading -
/does/ suggest Phytophthora. He stated "There are deep cracks running up
one or two the trunks".

But phytophthora attacks only living tissue, and spongy heartwood
is an almost certain indicator of fungal attack. The vigorous shoot
also argues against phytophthora, because that generally kills first
and subsequent fungal attack destroys the dead plant.

Verticillium and other fungi can also cause deep cracks in bark,
incidentally. I have a Cotinus coggryia with all of its stems down
to the heartwood for half their circumference, and it has been like
that for many years (it's Verticillium).

If the Grevillea was killed by either Phytophthora or Verticillium then
I made a hurried mistake replacing it with a Cotinus! I'll dig it up
when it's dormant, wash off the soil, and put it in a pot for a couple
of years. Not sure what I'll put in it's place; maybe a conifer.

--

Jeff

In article ,
Jeff Layman wrote:

If the Grevillea was killed by either Phytophthora or Verticillium then
I made a hurried mistake replacing it with a Cotinus! I'll dig it up
when it's dormant, wash off the soil, and put it in a pot for a couple
of years. Not sure what I'll put in it's place; maybe a conifer.

I wouldn't worry - it's had Verticillium for many years (probably
over a decade), and the main effect has to be keep its growth
down so that its shoots are only a couple of feet (rather than
six!). And, assuming the pathogen was in the soil, it took thirty
years for it to become infected. Cotinus are much tougher than
Grevillia.

Conifers are prone to fungal infection, too, and there's no way for
an ordinary person to identify such pathogens precisely. Whatever
you plant will be a risk.


Regards,
Nick Maclaren.