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<David Hanf>
posted
I am interested in using an instrument to determine if a tree is stressed. I have already used a SPAD meter, leaf temperature, and a pressure bomb. If anyone has suggestions for an instrument to do such a mystical task, i would like to hear what you think. The people that i have to work with do not necessarily have a keen eye for picking up visible stress factors.

Thanks

david
 
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<Russ Carlson>
posted
Reply to post by David Hanf, on April 12, 1999 at 10:02:07:

Stress is a very elusive thing, David. What kind of stress are you talking about? Water? Physical? Nutritional? I don't think that mystical, magical device exists (yet- I'm working on it).

To create a device to measure any type of stress, you first have to know what the measureable parameters are, and then you have to know what can be considered 'normal'. This is the biggest problem, since a tree is a huge sink of interactive processes. A tree might be measured as being under water stress in the middle of the day, but fully recovered by the next morning. Water stress might vary between individuals of the same species. It might vary depending on soil complexities, type and number of mycorrhizal colonization, and any of hundreds of other factors. And symptoms of one type of stress might mimic, or mask, the symptoms of another stress.

So take it one step at a time. Follow the concept of 'most limiting factor'- figure out what the most important stress factor is, and aleviate that first, then move on to the next.

As to people, the solution is to train them to recognize the stress factors, if that is within the scope of their job description. BTW, what postion do you hold? Arborist, researcher? I don't know many field arborists who use pressure bombs and leaf sensors [g].

Russ
 
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<David Hanf>
posted
Reply to post by Russ Carlson, on April 12, 1999 at 10:02:07:

Hey Russ,

I am a researcher who gets called in by people that i know. I really do not make any money by consulting, but could probably get a publication out of this work. The original problem was to get a "fail proof" technique that would give a warning sign before visible signs showed up. The problem is the time it takes to look for all the possible tress causing factors. The staff do simple tasks like watering and fertilizing and any pest control or fungiciding. There seems to be a resistance for them to learn new tricks or the employers have a resistance to pay for the added time. So, a simple once-a-month test is desired. I think, as well, that the best solution is to train a couple of people to keep an eye on them when they are not doing other work, but that does not seem to make sense to big business.

thanks for the advice
i will have more arguments to back me up now.

david
 
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<Russ Carlson>
posted
Reply to post by David Hanf, on April 12, 1999 at 23:08:17:

One simple thing you could do if watering is an issue. Soil moisture meters are easy to use, and can be helpful in sheduling irrigation. Prices start low and go up as accuracy increases. A simple 9 or 10 inch probe that is poked into the ground at various places can be a big help. Training and use is easy. Tensiometers are more accurate, but cost more and require more maintenance.

Another approach for an 'all-in-one" device might look at infrared devices. Ir can detect subtle changes in reflectance/absorption before the eye can see it. This can be expensive, and not easy to use reliably by most field personnel.

Have you ever noticed the effect with amber tinted sunglasses? The so-called 'blue-blocker' types cut much of the blue reflected light from plants, and enhances the contrast between the greens and yellows (browns). I find the effect quite helpful in spotting some early signs of stress.
 
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<David Hanf>
posted
Reply to post by Russ Carlson, on April 13, 1999 at 12:05:44:

I had never thought of the amber glasses thing, that might work.

On another message board someone mentioned IR Photography in an orchard situation. Something that i had thought of before is to use an IR night vision scope. This may pick up small differences between trees in the day or night.

Soil moister probes are good for strictly irrigation problems, but the virus, fungus, bacteria, and insect problems are the real bug-a-boo.

Thanks
 
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<Paul M Davis>
posted
Reply to post by david hanf, on April 13, 1999 at 19:56:41:

Infrared photography is used extensively in the mid-west to assess agricultural crop conditions. The trick is that one needs to know what to look for in interpreting the photos.

I see that Forestry Supply has come out with a manual band dendrometer to measure very fine (daily) changes in caliper. About $40 bucks apiece. Following daily size changes over time would allow one to track "normal" growth patterns for that specific tree, and possibly detect stress conditions before other visible symptoms appear.

telephone (800) 543-4203
www.forestry-suppliers.com
 
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<Kerry>
posted
Reply to post by Paul M Davis, on April 14, 1999 at 08:57:49:

I can't help but wonder if tissue pH and sugar levels might be good indicators. It's a subject I have intended to put some energy into researching, but time has flown away on me.

Ring anybody's bells? Any experience with such testing, and is it useful for "heading" stressed conditions off?

Best regards,
KWK
 
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<David Hanf>
posted
Reply to post by Kerry, on April 14, 1999 at 22:22:20:

Hey Kerry,

i have discussed sugar levels with others and the problem that we have thought of is that the sugar levels change from day to day as light intensity or sugar production in general change. We have not researched it yet and you may be the first to find that it will not be as sensitive to short term change as we thought. I'm "rooting" for you.
 
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<Russ Carlson>
posted
Reply to post by david hanf, on April 14, 1999 at 23:07:06:

Have you looked into the Shigometer? That uses electrical pulses to measure "vigor". I only tried it once, and wasn't too sure what kind of results I was getting. What are your thoughts on this?
 
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<Scott>
posted
Reply to post by Russ Carlson, on April 15, 1999 at 11:11:48:

I spent an afternoon with Shigo in Portland in '93 (maybe you were there Russ) and he discussed the Shigometer for vigor/vitality assessment. I seem to recall that he said it requires good baseline data for species, sizes, environment to compare to in order to make any meaningful interpretation.
 
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<Russ Carlson>
posted
Reply to post by Scott, on April 15, 1999 at 11:30:46:

In short, the tool is nearly useless for the field arborist. You can't get a good enough baseline from just a few trees, and who has the time (or can charge enough) to run all over the neighborhood to test trees to get a good site index?

Well, roofers don't use cement mixes often, either. [g]
 
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<David Hanf>
posted
Reply to post by Russ Carlson, on April 15, 1999 at 11:11:48:

I have read the litterature and it seemed to the owners of the trees, that it is too invasive and may introduce pathogens and may be "unsightly" in a public garden.
 
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<Russ Carlson>
posted
Reply to post by david hanf, on April 15, 1999 at 11:30:46:

The vigor testing with the Shigometer is not invasive. It uses a probe with two needles set about an inch apart, that is pressed through the bark to the cambium, where the reading is taken. It does not leave holes, and the readings can be taken in just a minute or two per site.

But again, the results require interpretation and calibration of the equipment. And there is a large initial investment.
 
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<Kenneth Marvin>
posted
Reply to post by Russ Carlson, on April 12, 1999 at 10:02:07:

David Hanf,
I think you might be my cousin from Indiana/Florida. If so, please contact me out here in Oregon at this email address:

rio_rama@hotmail.com

Thanks,
talk to you later!
 
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