Reviving "dry" tap holes

[saphound]

So, I went out today to check buckets around 1 pm. Low last night was 24 and at 1 it had just reached 50 degrees. Should be perfect right? None of my taps were dripping AT ALL. Nothing yesterday either when it hit 42. Before I went out I was reading a publication from UVM Proctor Maple Research Center titled The Timing for Tapping for Maple Syrup.
http://www.uvm.edu/~pmrc/tapping.pdf
Anyway, I learned that the tap holes don't actually "dry out", there's a microbe that interacts with elements of the sap that forms a gummy substance that clogs up the sap carrying tubes. And warm spells like we've had can really accelerate the problem.
So I go back to the house and get my drill and a new tap...I had to see if a new hole would run in the same tree. As soon as the bit came out, so did the sap. I put the new tap in and it's dripping 3 drops a second. SOB, I say. So I'm wondering if I redrill the original hole, what would happen. I pull the tap, and run the bit in there back and forth a few times, same 1 1/2 depth as it was. Sap runs out of the hole, I put the spile back in and it's running almost as good as the new one on the other side of the tree. Apparently, that gummy substance hadn't traveled into the tubes much, just sealed the ends, and the bit scraped that out and opened the tubes again. I was using the same 19/64 bit I used the first time, btw. So I go to the next tree, pull the tap and redrill..this time I decided to go a little deeper, maybe 1/4-3/8 deeper. I really wish I could post a video..newly replaced spile is now dripping like crazy, when a minute ago it wasn't giving a drop. I did the rest of my 12 trees and am now getting good sap again. I realize you guys with hundreds of taps probably wouldn't/couldn't do this, but anyone with just a few dozen taps might want to think about it if it seems their tapholes have "dried" up already.
Then again, maybe most of you knew this already, but I didn't. Also, it could end up a very short lived fix and clog up again real quick..I'll post that if it does.

[Cedar Eater]

I can't argue with your success. You didn't to any more harm by redrilling a dry hole than anyone else does by leaving it alone. You might have even opened up a new field of tapping research. Congrats.

[Soukup Farms]

I'm not sure of the science on the subject, but we did try this two seasons ago on our smaller 500 tap sugarbush. Mid season things seamed to "dry-up" even during great conditions. We got the idea to re-drill everything on an off day and gave it a shot. We used the same bit and same taps, just went about 1/4" deeper in each existing tap hole. Each hole began to run as soon as this was done, and the next day we were right back up to beginning of the season sap flow levels. I haven't tried this since mainly due to the time required, but we also see a huge improvement in the lifespan of the tap hole using check valve spouts.

[saphound]

Good to know, Soukup Farms, thanks. I'm going to go with those next year.

[michael marrs]

I'm not sure of the science on the subject, but we did try this two seasons ago on our smaller 500 tap sugarbush. Mid season things seamed to "dry-up" even during great conditions. We got the idea to re-drill everything on an off day and gave it a shot. We used the same bit and same taps, just went about 1/4" deeper in each existing tap hole. Each hole began to run as soon as this was done, and the next day we were right back up to beginning of the season sap flow levels. I haven't tried this since mainly due to the time required, but we also see a huge improvement in the lifespan of the tap hole using check valve spouts. I did this yesterday with some of my dry taps, and almost all of them opened up again

[DrTimPerkins]

Also, it could end up a very short lived fix and clog up again real quick..I'll post that if it does.

Sorry to burst your bubble, but it has been tried before.

If you drilled deeper, you opened up new vessels for flow. The pressure has to come out somewhere, so the flow will be through these new vessels out of the taphole. If you go deeper, you are actually creating a larger wound as well, which affects the overall tapping sustainability in the long-run.

What you've done is called "reaming". Typically it is done with either a slightly larger diameter drill bit, or drilling slightly deeper. In general you will produce more sap for a short period of time, depending upon the weather and microbial contamination level in the taphole. It generally is not done by commercial producers because the cost of retapping/reaming each taphole outweighs the benefits.

The 1/4" spout was actually invented for nearly the same purpose. Syrup was in short supply for a few years, so some manufacturers sold 1/4" spouts for tapping in the fall, then suggested reaming to 5/16" in the spring. Didn't work out....you're not removing enough wood/microbes to refresh the taphole enough to be highly productive again.

[DrTimPerkins]

I can't argue with your success. You didn't to any more harm by redrilling a dry hole than anyone else does by leaving it alone. You might have even opened up a new field of tapping research. Congrats.

1. Success may be only temporary.
2. If the hole is drilled deeper, it will cause a bigger internal wound.
3. Not a new avenue of research. It's been tried many times before.

[saphound]

Hi Dr. Tim, I was hoping you'd comment. Yeah, I had a feeling I wasn't the first to think of it..and wondered how long it would last, knowing the taphole must be teeming with those microbes. But my first hole, I didn't go deeper, or bigger. I used the same original bit that still has tape at the 1 1"2 inch mark...and it worked. Then I started going a little deeper. Anyway, so now I'm wondering..yes it's a deeper wound..but I wouldn't be tapping there again for a long long time, maybe never. Is it something that shouldn't be done? I don't want to give bad advice. Thanks.

[motowbrowne]

I've done it before. Usually with a bigger bit.

I view it as a management decision. It's not helpful to the tree, so I try to avoid it, but sometimes if you got a poor crop and a bunch of dry holes and a good forecast it's something to consider.

[saphound]

I'm thinking the same thing, motow..only if you have to in a poor year. But I don't have many years experience yet, so still a lot to learn. I'd like to know how much another 1/4" deeper will affect the tree. I wouldn't think much, but I really don't know.

[DrTimPerkins]

I'd like to know how much another 1/4" deeper will affect the tree. I wouldn't think much, but I really don't know.

If your original taphole was 1.5" deep, then an additional 1/4" deep taphole (same diameter) would produce a wound that is 16.7% larger (1.75/1.5).

Of course this also means that your opening up only 16.7% more vessels than the original taphole, so your increase in production would be about that much or maybe a little more. The additional depth of hole would also tend to dry up somewhat faster than the original hole as well.

Depth of taphole, size of taphole, length of dropline or height of tapping band all affect the sustainability calculation for maple production.

[saphound]

Hi Dr. Tim,
I get that it's going to be a slightly deeper wound, but I don't get how much that matters if the wood in that area has to be avoided in the future anyway for many many years. Also I didn't know the height of the tapping band had an effect..how so?

[DrTimPerkins]

I get that it's going to be a slightly deeper wound, but I don't get how much that matters if the wood in that area has to be avoided in the future anyway for many many years. Also I didn't know the height of the tapping band had an effect..how so?

Say that you have old tapholes and associated staining columns that have been buried by new wood growth on the tree. The idea is that you don't want to tap into those zones again until enough wood has regrown over the area so that you will not penetrate into the wounded area (tapping into old stained areas will reduce your yields significantly since these zones are non-conductive of sap/water). With a deeper taphole, it takes more time for a sufficient depth of wood to grow over that area than with a shallower taphole. For example, let's say you're drilling 1.5" deep. Assume that you're growing 0.1" of wood per year. It would take 15 yrs before you could safely tap in that area again and NOT hit an old stained column. No consider what happens if you drill 2.0" deep at the same growth rate. That means it would take 20 yrs of tree growth before you would not hit that old stained column. So a deeper taphole means that either: 1) you need to spread your tapholes over a larger area to have the same probability you will hit an old stained columns, or 2) you will (by chance) hit old stained columns more frequently. How frequently you hit the old stained columns is determined primarily by the taphole diameter, depth, number of tapholes, tree growth rate, and the size of the tapping band.

RE: height (size) of the tapping band. With buckets, this is defined as the lowest spot you tap and the highest spot you tap. With tubing, it is restricted to the areas you can reach with your dropline (typically ABOVE the lateral line). To illustrate, we'll use a ridiculous example....a 6" dropline. With such a small dropline, the area you can reach to tap is very small. After about 10 yrs you are going to start to tap into stained zones. Make that dropline 36" long, and it'll take a lot longer for that to happen. The size of the tapping band is a critical factor in determining tapping sustainability.

There are several papers in the "Recent Publications" section of the UVM PMRC website http://www.uvm.edu/~pmrc that touch on tapping guidelines (size of spout, depth, etc.). Several of these are grouped together under the heading "Tapping Guidelines" at http://www.uvm.edu/~pmrc/?Page=tappingguidelines.htm , including a "Tapping Zone Model" which is an Excel-based tool where you can put in your own numbers and see what happens under different scenarios. We are about 3.5 yrs in to a 5 yr review of several facets of tapping guidelines. Expect to see a lot more on the subject from us over the next 2-3 yrs.....some of which is fairly unusual in ways (that's all I can say for now).

[saphound]

I'm still scratching my head on the depth thing. The extra depth will be towards the heart wood, and the new growth is between the old hole and the bark, right? So if you get 1 1/2" of new wood after 15 years, and drill a new 1 1/2" tap hole, how would you ever reach that deeper stained wood? ..or why would it now take 20 years instead of 15 to cover that deeper stained wood? Sorry for being so dense. And thanks for those links, I'll def check them out.

[Ed R]

Saphound, You've got it. I'm a firm believer that tapping deeper will give you a lot more sap, especially on buckets. Your results show this. We had hired help tap a section of our woods one time instead of family and we were not getting that sap we should have. Checked the tap holes and they were 1.5 inches deep with a lot of older thick barked trees. Pulled the spiles and redrilled to our normal depth and the sap volume went up to normal. This was while it was still running ok. If I'm going to tap a tree and wound it I want to max out the potential benefit from that tap. I justify this by not taping as heavily as others do. I usually don't tap a small tree till it is 12" and I have 3 buckets on only a few of our very large maples. I've tried reaming 5/16 to 7/16 with no luck and since we tap to max depth we can't go any deeper. As you tap the same trees year after year you will hit brown wood once in a while (some of this is not from previous tapping). On buckets its not as big of a deal as with vac. Those are the taps that "dry" up first each year. You will get additional sap from your reamed taps but the majority of it will be from the added depth.

[DrTimPerkins]

So if you get 1 1/2" of new wood after 15 years, and drill a new 1 1/2" tap hole, how would you ever reach that deeper stained wood? ..or why would it now take 20 years instead of 15...

Because now you've reamed the hole deeper by 1/4-1/2".

[Cedar Eater]

I'm still scratching my head on the depth thing. The extra depth will be towards the heart wood, and the new growth is between the old hole and the bark, right? So if you get 1 1/2" of new wood after 15 years, and drill a new 1 1/2" tap hole, how would you ever reach that deeper stained wood? ..or why would it now take 20 years instead of 15 to cover that deeper stained wood? Sorry for being so dense. And thanks for those links, I'll def check them out.

You're okay after the first 15 years for the initial tap, but you run the risk of hitting the bad wood when you revive the hole by making it deeper.

[Ed R]

If your trees are lightly tapped the additional length of the wound channel would probably just reach more white wood unless your trees have a really shallow sapwood band.

[Cedar Eater]

If your trees are lightly tapped the additional length of the wound channel would probably just reach more white wood unless your trees have a really shallow sapwood band.

Unless you tapped very near the same spot 15 years ago.

[saphound]

You're okay after the first 15 years for the initial tap, but you run the risk of hitting the bad wood when you revive the hole by making it deeper.

CE..do you mean if I drill a hole 15 years from now and then revive that hole deeper again at that time? That I understand, but for some reason I don't think that's what DR. Tim is saying. Anyway, I'm not going to make a habit of doing it. Didn't need to last year and hope I won't need to again in the future. It's just something I'll have up my sleeve just in case.

[Cedar Eater]

CE..do you mean if I drill a hole 15 years from now and then revive that hole deeper again at that time?

Yes. That's what I mean. If reaming and extending dry holes becomes your standard practice, the increased depth increases the chances that you will tap into wood that has been damaged by previous tapping. You would have to increase the size of your tapping band to decrease the chance that you will drill into bad wood. If you only do it the first year that you have tapped the tree, no problem.

[woodey24]

Soooo, as a newbie, is it 1.5in or 2in that is recommended for tapping? We probably pushed the 2 in mark this year but want to make this a long term endeavor. I used the 5/16 treesavers this year and plan on using them next year just attempting to put some on tubing. I will also take this opportunity to thank Dr Tim and everyone else for the continued help. I am sure there has been some stupid sounding questions coming from lenawee county...

[Cedar Eater]

Soooo, as a newbie, is it 1.5in or 2in that is recommended for tapping? We probably pushed the 2 in mark this year but want to make this a long term endeavor. I used the 5/16 treesavers this year and plan on using them next year just attempting to put some on tubing. I will also take this opportunity to thank Dr Tim and everyone else for the continued help. I am sure there has been some stupid sounding questions coming from lenawee county...

If you're not using vacuum, you can tap deeper than 1.5". I think Dr. Perkins has been quoted as saying you can go as deep as 3" on gravity systems. But once you use vacuum, you run the risk of pulling too much from the tree, using the same tree diameter guidelines that you would use for gravity. You have a very wide tapping band on gravity. On vacuum, your tubing height kind of narrows it, especially when the tubing is high because you're at or close to the top tree of the line. If your tubing is at 6' you would be tapping from around 6' up to the length of your drop tubes. That's maybe up to 9'. You can tap higher, but at some point the tree pressure drops too low or it otherwise just isn't worth it. Tapping deep and having a narrow band increases the chance that you will hit bad wood in the future.

[woodey24]

@ Cedar Eater: When you say vacuum, you mean by machine? I don't think I plan on getting to that point, but I didn't picture being where I am today. The narrow band you speak of is how much of the tree you tap? So if the top of your run always has to be at 9ft, you can only work your way around the tree and not up and down? I have read on here I believe 10in as the minimum diameter prior to tapping? I am learning the vocabulary, slowly but learning, a maple dictionary would be a good tab to be able to click on this site and save some of the misinterpretations or questions. Dr Tim had clarified how far the tap holes need away from the old from year to year so I assume that I can work around a tree then move up or down 15in or so and then work around again? With this the tapping surface should outlive me...How much snow/ice did you get out of this last week? I am just south of the cold line and haven't been getting the cold nights like you.

[Cedar Eater]

@ Cedar Eater: When you say vacuum, you mean by machine? I don't think I plan on getting to that point, but I didn't picture being where I am today. The narrow band you speak of is how much of the tree you tap? So if the top of your run always has to be at 9ft, you can only work your way around the tree and not up and down? I have read on here I believe 10in as the minimum diameter prior to tapping? I am learning the vocabulary, slowly but learning, a maple dictionary would be a good tab to be able to click on this site and save some of the misinterpretations or questions. Dr Tim had clarified how far the tap holes need away from the old from year to year so I assume that I can work around a tree then move up or down 15in or so and then work around again? With this the tapping surface should outlive me...How much snow/ice did you get out of this last week? I am just south of the cold line and haven't been getting the cold nights like you.

No, vacuum is vacuum. It doesn't really matter to the tree whether it comes from a machine or a downhill slope. It still pulls a lot of sap out of the tree and you don't want to pull too much.

Yes, the tapping band when you're only using buckets, bags, or drop tubes to jugs extends from maybe as low as 18" up to 6'. You're relying more on tree pressure so you favor the lower end of that, but you can conveniently work within that range. When you make a 3/16" tubing line for natural vacuum, your tapping band is set by where the line crosses the tree. So at the top tree of the line, it will be up high above the ground unless the ground slopes as much as the line slopes. On flat ground, setting the tubing line higher than 6' is a pain and you have to use a stepladder (or something) to utilize your tapping band. Tapping below the line height can be done, but making the sap crawl uphill to get to the line defeats the purpose of setting the line high.

I think most people use 10" as the minimum diameter (at breast height (dbh)) to avoid stunting the tree growth too much. You can probably tap smaller trees without killing them, but it slows their growth more. I you are planning to cull any maples because your tree density is to high, you can deliberately tap a small maple to death and then cut it down for firewood.

Your tapping pattern is a personal choice, but I plan to go S, N, W, E the first four years, then up 6" and over to SW, NW, SE, NE for the next four, then up 6" and back to S, N, W, E and etc. until I think it's safe to go back to the bottom of the band.

We got 6" of fresh snow with some ice and rain in the middle. Supposed to reach the forties today and the fifties by Sunday. I will probably collect again tonight after a two day break in gathering.