Using cavitation sound on xylem to detect water stressed Ohia tree to detect the ROD fungus
According to https://www.popsci.com/environment/article/2013-04/sound-thirst trees make a sound when they can not transport enough water to their body. This sound cannot be heard by our ears but if we listen using a stethoscope. This sound generated in the xylem is when cavitation is formed.
Cavitation is the formation of empty space within a solid object or body, meaning the formation of bubbles in a liquid. At the recent meeting of the American Physical Society, scientists from Grenoble University in France presented research that not only were they able to determine that drought-stressed trees make noise, they were also able to show exactly which process created the sound.

To really grok the research, it's helpful to understand how trees transport water. Trees draw ground water up through specialized tubes called xylem, relying on intermolecular forces between water molecules and themselves, and water molecules and the sides of the tubes, to create a single column of unbroken water in each xylem tube. But as groundwater dries up, the trees must pull harder on the remaining water; if the pressure is greater than the strength of the intermolecular forces, the column of water breaks and an air bubble forms. This process is called cavitation. Too many air bubbles can mean death for the tree.
To ensure that these air bubbles were the culprits behind the acoustic signature of drought-parched trees, the researchers mocked up a tree in the lab. They placed a thin piece of pine wood, complete with its xylem intact, into a capsule filled with a gel. As the researchers evaporated the water out of the gel -- a test "drought" -- they simultaneously recorded video and sound of the cavitation in the xylem. The researchers discovered that about half of the sounds made by a tree are due to cavitation and that the process has its own unique acoustical signature. In the future, the researchers say, forest managers could use a hand-held acoustic device to identify water-stressed trees before permanent damage sets in.
In our case since the ROD infected Ohia tree can transport less water than it needs, it is obvious that cavitation will occur at the upper part of the tree. By using devices that listen in to the part of the tree we can identify which tree is struggling to transport water. And then we have the symptom for the ROD fungus,
 
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Hey @Anteneh Gashaw - this is a really good idea. Good job researching the topic and finding parallels from other fields of research.

I think a stethoscope alone probably won't work - it's going to be more than just listening for a specific sound in a tree, it is going to be more like, looking for an acoustic signature. The last line is promising: "In the future, the researchers say, forest managers could use a hand-held acoustic device to identify water-stressed trees before permanent damage sets in."

I think you are on to something!
by Tom Quigley
@Hal Holmes do you have any thoughts on this?
by Tom Quigley
Public note: if anyone can find the actual research article referenced in this blog post, it would be helpful!
by Tom Quigley
I'm not sure what article this story referenced by the article, it could be this one: https://link.springer.com/content/pdf/10.1007/s13595-013-0317-5.pdf

But here is a little older one by the same researcher that outlines the mechanics and detection of cavitation in trees: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.716.4794&rep=rep1&type=pdf

And a much older one that links cavitation to pine wilt : http://www2.kobe-u.ac.jp/~kurodak/1991.04-1.pdf



by Hal Holmes
Thank you, @Tom Quigley , For the record, I just do not find possible solution researchs, I draft/ invent possible solutions and it happens to be I got lucky with some of my idea that some researches have studied it and I has become my reference. I am glad for the researchers for conducting it but if they have not I would definitely proceed to do it my self if I had funding.
I am glad new scientists are coming on commenting on my projects.
by Anteneh Gashaw
@Hal Holmes Thank you for the information. Please keep it coming.
by Anteneh Gashaw
@Anteneh Gashaw any further work on this idea? I see this as very promising.
by Tom Quigley
@Tom Quigley I know I took my time presenting further on this idea. I have been occupied with searching, reading and designing a possible device that could detect the cavitation sound better than stethoscope. I have made some progress and I will share when I feel a little confident on the design very shortly. But I think I could use some help if anyone has a design for a device that could achieve this or someone that could suggest me where to focus as I am researching many years of research in the short period of time.
I do not what you could do but please invite other researchers who may give some contribution.
by Anteneh Gashaw
@Anteneh Gashaw Well, I have been giving it some thought, for what that's worth.

Knowing that the sound makes a different noise is useful, but it needs to be proven that the 'ohi'a tree actually has the same effect. Otherwise, it's not a lead. So that should be step 1 - identifying a researcher in Hawaii that can confirm. I think it should be as simple as replicating the methodology from the research you cited, and see if 'ohi'a presents the same 'cavitation sound' as the trees in the paper.

Then, you'll need to confirm that there is a difference in the sound between a tree affected with ROD and a tree that is not. This will likely need to be confirmed experimentally (in the lab) and then again in the field. This is the tricky part because I don't know that the past researchers actually did this in the field, just the lab.

Once all this is confirmed, you'll have a product on your hands. Then it's a question of building something to ID the sound in the tree.

From here the question is: do you need to detect a CHANGE in sound, like a "tree pacemaker" (ie when it starts to gurgle) or just the sound itself, more like a "tree stethoscope" (identifying a gurgle)? I don't think we'll know that until we learn more about the tree.

Either way, my guess is that you'll need to use an AI algorithm to pick out the sound from all the noise.

Have you thought about reaching out to the researchers who wrote that paper?
by Tom Quigley
@Tom Quigley you make it sound easier now, it may because it is the right procedure to follow. but all the steps you mention involves things I could not manage to do from where I am (Ethiopia)
As you said the best thing to do is to involve the already at the task researchers and see what we can do further.
I will email J.B Friday on this matter. Please do the same because you obviously have more connection than me.
by Anteneh Gashaw
Also, I have not contacted the researchers who wrote that paper.
by Anteneh Gashaw