5/16 or 7/16

[morningstarfarm]

what are the pros and cons of the different size spouts?

[Thompson's Tree Farm]

In my humble opinion, there are no advantages to 7/16 spouts.. 5/16 deliver virtually the same volume of sap for half the tree injury. It takes less power to drill the hole with the smaller tap. 'Bout the only advantage I can think of for 7/16 is that if you already have them, you don't have to buy new ones.

[maple flats]

5/16. just as much sap and better for the tree. 7/16. no more sap and more damage to the tree. With 5/16 you tap 10" and larger, with 7/16 you tap 12" and up. 7/16 was the std before it was determined that 5/16 was good for sap flow and less damage to the tree, less stain and a tighter tapping pattern year to year.

[morningstarfarm]

Hmmm thats what I was thinking..I've been using 5/16 for years and was kinda wondering if I was missing something

[farmall h]

'Bout the only advantage I can think of for 7/16 is that if you already have them, you don't have to buy new ones.

That is true. If I had the time and $ I would change them. Plus have been on gravity feed for many years.

[WESTVIRGINIAMAPLER]

On gravity, I think you are going to get aprox 15 to 20 percent more sap with 7/16 vs 5/16, but on vacuum, there appears to be basically no difference.

[farmall h]

That's the way I understood it over the years. I am just "dabbling" in vacuum this year. My gravity feed is mighty steep and tends to create it's own natural vacuum. One thing obout vacuum...you definately can hear the leaks!!!

[jr.tompkins]

I dont own very much land, so most of the trees I tap are on other peoples land and I usually pay them in syrup at the end of the season. Usually I approach the door of a suspected bush with both different types of taps in my pocket and explain to the person that tapping trees does not hurt them, and I show them the difference in the tap hole size and explain how much faster the tree will heal. Its a great selling point. Also after the first year of them finding essentially "Free" liquid gold in their mail box they are happy to have you back the following year.

[Groves]

On gravity, I think you are going to get aprox 15 to 20 percent more sap with 7/16 vs 5/16

Does this apply to buckets, I assume? Seriously? 20 percent?

[Russell Lampron]

My experience with 5/16" taps and buckets is that the sap yield is the same per run and that the tap holes stay open twice as long yielding MORE sap. Most of the tap holes will stay open for 6 weeks with the 5/16" while with the 7/16" they start to close up after 3 weeks and by 6 weeks less than 1/2 are still running. I use the Leader hookless bucket spouts and boil them before I tap.

[Toblerone]

Here is the PMRC small spout study: http://www.uvm.edu/~pmrc/smallspout.pdf

On gravity: "For the five year period, the yields averaged 12.54 gallons/taphole for small spouts and 13.29 gallons/taphole for large spouts, or 94% as much sap using small spouts compared to large spouts."

Vacuum: "There was no significant difference between yields for either size spouts in both years."

Taphole drying: "In two of these three years, both sized tapholes dried at about the same time; while in the third year (2000), the tapholes fitted with small spouts ran about two weeks longer than the 7/16” tapholes."

Taphole depth: "Holes that were 1 ½” deep yielded 98% as much sap as holes 2 ½” deep for either sized spout, while holes ¾” deep yielded approximately 86% as much sap as holes 1 ½” deep."

[DrTimPerkins]

This is a "idealized" summary figure of the UVM PMRC research on small spouts in terms of sap yield. In part it comes down to how rapidly sap can come out of trees.

With a large taphole, sap will run out very quickly, and slow down very quickly. With a small spout, it'll run out a little more slowly, but still the majority of sap can come out in a reasonably short flow period.

Under vacuum the rates are even faster. Under gravity, the rates are slower. In some years (once every 3-5 yrs) with a preponderance of short thaw periods, the sap in the tree can't get out of the tree fast enough with small spouts under gravity, so the yield is somewhat diminished under those conditions.

This also explains why sometimes it seems that 5/16" spouts actually "increase" sap yield compared to 7/16" spouts (on a % basis).

With microspouts, the hole is just too small for the sap to get out of the taphole fast enough for the tree to be "exhausted" of its sap in an average flow period even while under vacuum.

Please do not copy this figure and repost elsewhere without proper attribution.

http://wcvt.com/~perkins/smallspouts.jpg