Dr. Perkins Study on Time to Tap

[backyardsugarer]

Dr. Perkins. Thanks for providing the link to the article on time to tap.

According to that research and the fact that I am on 1 year old tubing and in the process of installing CV's and I run vacuum, I should be able to tap anytime I want now. As soon as it warms up (not in the 10 day forecast) I plan to tap and take advantage of this research and early season runs.

Chris

[DrTimPerkins]

According to that research and the fact that I am on 1 year old tubing and in the process of installing CV's and I run vacuum, I should be able to tap anytime I want now. As soon as it warms up (not in the 10 day forecast) I plan to tap and take advantage of this research and early season runs.

It is not a formal recommendation, as we want to follow-up last years early tapping with CV to see what happens, however given that we are now going to have about 75% of our main bush on CVs this year (previously it was max 25%), we will also begin tapping within the next couple of weeks, which is a few weeks earlier than normal for us.

We did tap some trees for research purposes this past Friday.

[maple flats]

I missed the article, where can it be found? Link?

[BryanEx]

I missed the article, where can it be found? Link?

It's available on the Proctor Research Center web site in the right hand menu bar.
http://www.uvm.edu/~pmrc/tapping.pdf

- Bryan

[Frank Ivy]

Thanks for the research.

The most interesting part, for me, was table 3 (appears to be a typo in either run date or tap date for 3nd column, 1st data point). The clear implication is that, for us open-air tappers, "dry tap" is an irrelevant concern.

Regarding discussion of "reduction in flow" at the end of the year, there's an unstated assumption that seems, to me, critical to the analysis - that flow is being reduced by some outside force - i.e. something independent of the tree.

Is it not obvious, and perhaps even likely, that the higher production seen in much later-tapped trees (Table 2B, 3/21 tap date) is not the result of "fresher taps," but simply the result of the tree having a full tree's-worth of tap left to give?

The experiment that could settle this would be to repeat 2B but don't draw sap from the taps - simply tap the early trees as usual, and allow check valve to stay closed until cognate trees are tapped several weeks later.

If flows are the same, and higher than earlier tapped trees that had sap removed, then the "total available sap" concept would be supported.

In any case, thank you for the experiment - makes me less hankering to get out there and tap early.

[DrTimPerkins]

Is it not obvious, and perhaps even likely, that the higher production seen in much later-tapped trees (Table 2B, 3/21 tap date) is not the result of "fresher taps," but simply the result of the tree having a full tree's-worth of tap left to give?

Maple trees will exude sap during thaw periods, and then refill with water drawn up from the soil when they freeze (during the actual freeze up, not after they are frozen). So a tree doesn't have a set amount of sap in it....it is more related to the number and frequency of freeze-thaw periods.

Taphole "drying" is caused by microbial contamination of the taphole.

[Frank Ivy]

Maple trees will exude sap during thaw periods, and then refill with water drawn up from the soil when they freeze (during the actual freeze up, not after they are frozen). So a tree doesn't have a set amount of sap in it....it is more related to the number and frequency of freeze-thaw periods.

Taphole "drying" is caused by microbial contamination of the taphole.

What is the conventional logic as to why a tree tapped later in the season will crank out more sap per tap per day than a tree tapped earlier in the season? Hole blockage?

Has that ever been directly confirmed with an experiment designed to control for volume extracted? For example, tap and spigot the holes all at the same time, but don't extract from 50%. In mid to late March, open up closed 50% and check flow. Bacterial count should be about the same in both groups. Compare flow rates.

Is there any paper on the mechanism by which bacteria slow flow?

[maple flats]

It is not a formal recommendation, as we want to follow-up last years early tapping with CV to see what happens, however given that we are now going to have about 75% of our main bush on CVs this year (previously it was max 25%), we will also begin tapping within the next couple of weeks, which is a few weeks earlier than normal for us.

We did tap some trees for research purposes this past Friday.
Dr Tim, Why is it you are not all on CV's, is it for research purposes?

[WESTVIRGINIAMAPLER]

What is the conventional logic as to why a tree tapped later in the season will crank out more sap per tap per day than a tree tapped earlier in the season? Hole blockage?

Has that ever been directly confirmed with an experiment designed to control for volume extracted? For example, tap and spigot the holes all at the same time, but don't extract from 50%. In mid to late March, open up closed 50% and check flow. Bacterial count should be about the same in both groups. Compare flow rates.

Is there any paper on the mechanism by which bacteria slow flow?

In my opinion it is because the days are longer, thus more thawing and the wind is not as cold and the temperatures are more conducive to sap flow along with ground warmer later on the season vs earlier. Of course, this is not always this way, but in the overall picture if you compare it over many years.

[DrTimPerkins]

Dr Tim, Why is it you are not all on CV's, is it for research purposes?

Yes. We have to have something to compare them to so we can tell how much more we're getting than conventional systems. We are definitely increasing our use of them though. If we were not doing research, I'd have them throughout our woods.

[DrTimPerkins]

Has that ever been directly confirmed with an experiment designed to control for volume extracted?

No need to. Studies done over a century ago have established the basics of sap flow. It is well established that volume extracted over a season can be, at times, far in excess of what is stored in the tree at one time. Other studies have shown the uptake mechanism. There is no need to control for volume.


Is there any paper on the mechanism by which bacteria slow flow?

There are several papers and theses. Most of these studies were in the 1950s and 1960s. If you read some of the recent CV papers on http://www.uvm.edu/~pmrc you will see the citations for these papers.

[Frank Ivy]

Nm,,,,,, nm

[Frank Ivy]

Dr. Perkins - Ok. So I took the time to go read your silver paper and to pull the citation that you offered for the proposition that microbes cause tap "drying."

I reviewed the Naghski 1955 Applied Microbiology paper.

Frankly, I was sorely disappointed that this paper is even cited at all, forget about cited as any kind of support of the hypothesis that microbes cause sap flow reduction.

The paper does not follow the basic principles of the scientific method, and is thus only an anecdote dressed in formal garb.

Specifically, Naghski only reports data for 4 holes - 3 normal and 1 "sterile."

With an n number of 1 for the test condition, results are meaningless. It is fundamental to science that you must sample a population to estimate population effects, and not simply pick one individual. Given that the three "normal" trees showed extremely large variability of sap flow time, there is a 1 in 4 chance right off the bat that the "sterile" condition would be, all else equal, the one that flowed the longest!

Further, even we ignored that fatal error, Naghski only, at best, demonstrates a correlation between flow cessation and microbe count.

It is also fundamental to science that correlation is not causation.

If you believe that the appearance of high microbe counts at flow cessation means that the microbes are causing the flow cessation, then you must also believe that the appearance of large numbers of rescue personnel at the time of natural disaster means that the rescue personnel caused the disaster. The results in Naghski could be explained, for example, by the simple observation that, when flow slows in an open tap tree, the medium of microbe growth (sap!) is resident in the tap longer, thereby leading to increased microbe counts!

Finally, Naghski's reference to a second test is meaningless, as there are no data, and it's unclear what the methods were.

Conclusion: Naghski is not a scientific reference - it is a nice anecdote, and, if that's the best support for the notion that bacteria cause flow cessation, then the question is still open as to what causes flow cessation.

I note, with some humor, that your silver paper indicates that several "anti-microbial" agents were tested to attempt to keep taps open longer, but that the only one that worked well was PFA. BUT, turns out, PFA was damaging trees by preventing wound closure.

Um. Has anybody even thrown out there that it was THAT effect of PFA - injuring the tree to prevent wound closure - and NOT the anti-microbial effect that made it work?

Anyway, I really don't have the inclination to pursue this. There is a very obvious and very simple way to test this - I've already suggested it.

Tap two sets of trees. Use the check valve system. Draw sap from 1/2 for a month, then draw sap from the other half as well. If production from both is different, then the microbe theory should be questioned more thoroughly.

[DrTimPerkins]

Dr. Perkins - Ok. So I took the time to go read your silver paper and to pull the citation that you offered for the proposition that microbes cause tap "drying."

I reviewed the Naghski 1955 Applied Microbiology paper.

Frankly, I was sorely disappointed that this paper is even cited at all, forget about cited as any kind of support of the hypothesis that microbes cause sap flow reduction....

blah, blah blah ....

Frank....Is polite discourse beyond your abilities? I will give you the benefit of the doubt and assume that it is not, and try to answer your questions, as scattered as they were.

Naghski was FAR from the only researcher noting this effect. He was simply the first who suggested it, which is why that paper was cited. It is convention in science to give credit to the person who proposed the idea initially, regardless of whether they were able to fully demonstrate the soundness of their hypothesis. Yes, while studies of that time do not follow normal convention, it was not uncommon for papers (of that time) to read like this and report on studies of this type. It was over 50 yrs ago....and times have changed considerably.

Several other studies followed this. Some were published in maple literature, some were published in scientific literature (which are rarely read by maple producers), some were MS theses (with parts never published, and thus not widely available to those outside of this field of work). Some studies were just never published (not terrifically uncommon). The end result of all of these studies is that the majority of tree physiologists widely accepted that taphole drying in maple trees (and some others) is caused by 1) the wound response of trees and 2) plugging of vessels by microbial slime. Sterile tapholes (which are actually quite hard to keep sterile) will produce for quite a long period of time, up until the time that the freeze/thaw period ends, and the normal summer transpiration (SPAC) model of water movement in trees begins.

Furthermore, while the study you propose has not been done, I doubt that it will EVER be done. I can only presume that your suggesting it stems from a poor understanding of the sap flow dynamics of maple trees and of the research in this field for the past 100 yrs. The amount of sap in a tree over a season is NOT static. There is not a set reservoir of sap to be collected. Trees take up water from the soil during the freeze phase, and exude sap during the thaw phase. This has been documented since the mid-1800s. There is absolutely no scientific reason to do the study you propose. It only makes sense to do it if you have a lot of money to spend and want to prove what we already know to be the case....that sap moves up during the freeze phase, and down during the thaw. If you really want me to study that....feel free to send a large check. Without that....(and even with it), it is a complete waste of time. I don't presume to tell you how to be a lawyer....please don't think you can be a scientist after reading a few papers.

If you wish to continue this conversation, I would suggest you take about 2 weeks to go to a good research library (you won't find it on the internet) and go to visit the 3 USDA stations and 4 University libraries (or get interlibrary loans) to read the reports and theses that demonstrate that SAP FLOW CESSATION IS CAUSED BY MICROBIAL CONTAMINATION OF TAPHOLES. This has been adequately demonstrated in my professional opinion. After that, I would be happy to continue this converation.

While you're at it....look into the literature on the dozens of studies on how PFA affects trees. You might also want to brush up on the theory of water (sap) movement in trees. Unless you are exceptionally quick and have NOTHING else to do, all that reading and thinking should take you at least 6 months. So feel free to start asking questions again in August 2011.

[Wardner in Tewksbury]

Dr. Perkins,

I think your last post may be the terminal post for this thread so I am taking the liberty to draw your attention to a related thread I started on Sunday. You had previously indicated you were unavailable last weekend (plus several days later) and may have missed it.

I know you have an interest in microbial pollution regarding fittings and lines. I am wondering if the surface treatment described in my link below has been evaluated by the maple industry or the UVM research facilities.

http://mapletrader.com/community/showthread.php?t=10958&highlight=anti-bacterial

[3rdgen.maple]

Now that is how you respond to a post. Dr. Tim Perkins I wouldnt and Im sure everyone else but maybe one guy on here will hold anything against you if you do not entertain these type of post any longer. Just keep doing the work you do and dont waste your time. By the way the blah blah blah was the best part lol.

[DrTimPerkins]

I know you have an interest in microbial pollution regarding fittings and lines. I am wondering if the surface treatment described in my link below has been evaluated by the maple industry or the UVM research facilities.

I did see the thread, but have no knowledge of it, so did not reply. Interesting idea. We'll see where it goes.