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<Jerry Dicker>
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I have recently purchased a PICUS for decay detection in the bole of standing trees. Have any guests or members here got one? I am particularly interested in the green area on a tomogram. The dark and light brown indicate solid wood and the white, blue and violet indicate cavity or decay. To assess the tomograms requires experience and there is very little experience around on this relatively new piece of technology. I am based in Bristol, UK.
 
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<Mark>
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No, I don't have one. Can you get experience by using the device, along with tree autopsy, to compare readings from known samples? If you looked at same-tree-species sections, having sound wood or various flaws, perhaps you could work up some predictive consistencies? Perhaps a photo gallery of tested wood in various categories? Of course, the testing device might add dimension to other clues and observations, but do you expect it to be the definitive source of information about hidden conditions?
 
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<Mark>
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I decided to search online about this technology, and found the following site (pdf) which has pictures of tomograms and trunk cross sections of tested trees.
picus pdf
I'm thinking that the tomograms generalize the flaws to various degree. (An analogy that comes to my mind is of the vague image of someone's form as seem through a privacy glass such as a shower door.) Cracks need to be interpreted. White rot in one picture seemed somewhat vague in the tomogram. I think it would be great if there was a picture data base of documented tomograms and cross section photos explaining conditions found during autopsies. It would also be good to deal honestly with situations where picus testing has not resulted in useful information. For instance, if there are certain conditions that typically are not defined well by a tomogram.
 
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Thanks, Mark, for your interest. I checked the pdf file you mentioned and it has the same pictures as in my instruction booklet. (1)I agree it doesn't show cracks very clearly. (2)I thought the white rot in beech had quite a good correspondence between photo of tree cross-section and tomogram (3) I guess they only show the best examples. We need good and bad results to compare, as you suggest (4) Ustulina deusta shows up well in two of their examples, the first and the last, but I recently did a sycamore (Acer pseudoplatanus) which had a load of Ustulina deusta fruiting bodies and it showed nothing on the tomogram. The owner retained it but I recommended serious reduction. When it falls over I'll post a picture on my website! Decay caused by Ustulina deusta is traditionally hard to detect with drills, isn't it.
 
Posts: 2 | Location: UK | Registered: Wednesday August 20, 2003Report This Post
<Mark>
posted
Jerry, I am a novice at diseases of trees. Thank goodness for an abundance of information resources online.
I thought the following reference might interest you.
re: Ustulina deusta & its detection
And here's another reference to picus detection of Ustulina deusta, though not first-hand.
UK Tree Care
I have no experience at drilling to detect this disease, but I read that it is characterized as a butt rot. So that's where I guess the focus of testing would be. Might it show up better with an increment borer?
 
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Hi Mark and any others reading. The problem with Ustulina is that it destroys cellulose first and leaves a very brittle remainder of lignin - ceramic-like according to David Lonsdale. So neither drilling nor ultra-sound will detect it. I'm not sure about an increment borer. We wait to see if the Picus can do so. Lonsdale says Ustulina can extend 4m or more up the stem, even in the central wood, AND down into the roots. So you can get windthrow or trunk fracture. And it's not rare. Jerry
 
Posts: 2 | Location: UK | Registered: Wednesday August 20, 2003Report This Post
<Scott>
posted
The German users of Wessolly's pulling test using the Elastometer argue that whether it's Utulina or some other deeca, it may extend blew ground or out into roots and that nether boringnor tomography alone will provide as definitive a pocture as the Elastometer.

Ustulina, compinds the problem as I understand it by giving false or unreliable readings of density when using Reistograph or Siebert borings.
 
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