Picus sonic Tomograph

[Fungus]

How many years between Picus scans would give decent data to see if the decay is progressive?

 

Douglas,

As I already said in a private message, Picus scans do not produce reliable in situ data on the extent of white rot with selective delignification caused by Ganoderma species, even if you repeat them after some time.

[ScottF]

We've had ours for about 18 months now, and it gets used most weeks. I find it extremely useful, and on balance I'd say it's allowed me to be more risk-tolerant as I can reasonably quantify the extent of decay- that's not necessarily to say the severity. That said, this tool will always be one of many, and the not dominant one. Where practical, we just bring it out with us if we're doing condition assessment work and use it to undertake further examinations of trees which have already been flagged by traditional VTA techniques.

 

What I would say is that I think, as with anything, you get better at interpreting the results with use. I've learned when what appears on screen as an area of decay is more likely to be an inclusion or crack, or when the pattern of density loss is telling (i.e. undifferentiated blotches of decay with no obvious wall formation in larches with honey fungus).

 

In terms of its limitations, it does struggle with K. deusta (this has been documented in research elsewhere); not so much in identifying extent but severity. I've found following the Resistograph to verify wall thickness around the pattern of decay very useful.

 

If I didn't have one and was buying it in on a day rate, for instance, I guess the tree would have to have aroused strong suspicions first of all, and then would have to be of value, either to the client, or in landscape or ecological terms to justify it. I've heard of whole avenues of trees getting Picussed and it just seems like a waste of resources. You get a quick and clear output, but they are fiddly to set up and it does take time.

 

Used well, they're a really helpful complement to traditional techniques, and can provide a visually easy to understand image for the client (versus a Resistograoh trace, for example.)

[armybloke]

Good post ScottF. I, like you, gain experience with practice (see previous posts in this thread). Do you have any comment on brown rotters v white rotters and the ease in which they are detected?

[Fungus]

I can reasonably quantify the extent of decay- that's not necessarily to say the severity.

In terms of its limitations, it does struggle with K. deusta (this has been documented in research elsewhere); not so much in identifying extent but severity. I've found following the Resistograph to verify wall thickness around the pattern of decay very useful.

 

Scott,

How much experience do you have assessing the extent and severity of the white rot with selective delignification caused by Ganoderma australe in tree species such as Aesculus, Platanus, Acer and Tilia and did you (always) use a resistograph to verify the data of tomography ?

[ScottF]

It's funny , Gerrit, but the bulk of the trees I end up Picussing tend to be presenting with K. deusta; I don't tend to see a great deal of Ganoderma. This probably has a great deal to do with the fact that many of the site we're looking at are schools, parks, development sites etc where trees are routinely damaged by the installation of new infrastructure, paths and the like. Hence the Kretzschmaria. Of course, given that most of the action's taking place below grade, it's uses are limited.

 

Looking quickly back through records, the trees which I've examined with G. australe have been sycamore, beech and eucalyptus. The Euc (see pics) was interesting in that the reading suggested that there was cracking co-related to the likely pattern of decay (and the positions of small sporophores near the ground). I thought that the decay might be causing local dessication which produced the cracking? That's not to say that the cracks shown might not have been interpreted by the software as decay (as it occasionally does, but not often).

 

I recommended this one be lightly reduced, as it already had a really favourable form (low and wide). Naturally, the client got some clown to "reduce" it for them (cheap and cheerful local butcher), and he pollarded it to a stem. When it finally dies, I'll dissect it and see...

[Tony Croft aka hamadryad]

This is turning into a fine thread

[Fungus]

the trees which I've examined with G. australe have been sycamore, beech and eucalyptus. The Euc (see pics) was interesting in that the reading suggested that there was cracking co-related to the likely pattern of decay (and the positions of small sporophores near the ground).

 

Scott,

Thanks, valuable documentation .

Did you in this case and all other mentioned cases - especially on beech - check the spores microscopically to be 100 % certain of G. australe and could the small sporophores near the ground on Eucalypt be diagnosed as panic fruiting ?

[ScottF]

I generally rely on the old eyeball, but having followed a few of your threads, this may well be something I'll look to do in certain cases.

 

in arb consultancy we're often constrained available fees (which equals time) for this sort of detail. It returns to the idea of educating our clients and getting them to ask more of us.

[Fungus]

I generally rely on the old eyeball, but having followed a few of your threads, this may well be something I'll look to do in certain cases.

 

Scott,

As you will have understood from my threads, for evidence of either G.australe or G. lipsiense being the pathogen, in quite a few cases microscopical identification is necessary.

Couldn't there be an identification service by a mycologist or institute like the service I rendered, organised by the AA and/or ISA for their members ?

Edited November 13, 2011 by Fungus

[RobArb]

Scott,

As you will have understood from my threads, for evidence of either G.australe or G. lipsiense being the pathogen, in quite a few cases microscopical identification is necessary.

Couldn't there be an identification service by a mycologist or institute like the service I rendered, organised by the AA and/or ISA for their members ?

 

In an ideal world...