For the past several years we have been conducting research and extension on tapping birch trees for their sap and syrup production. Several articles have appeared in this publication and others on the merits and pros/cons of tapping birch trees after the maple season is over. In 2105 we had funding from the Northern NY Agricultural Development Program and Cornell University’s Agricultural Experiment Station to conduct additional trials on tapping birch trees. There are many aspects of birch tapping that are similar to maple and other aspects that are entirely different, and more research is necessary understand the nature of these differences and how to best make use of the birch resource.
This article presents some of the lessons learned to date. We had research collaborators collecting data at several sites in New York, including Cornell’s Uihlein Forest in Lake Placid the Arnot Forest in Van Etten, Brandy Brook Maple Farm in Ellenburg, Farmhouse Maple in Dexter, Millbrook Maple in the Catskills, and the Paul Smiths College VIC. There is still a lot more research to do and our findings at this point are preliminary, but it is useful to get the data we do have out there since very little has been published so far on birch tapping in eastern North America. This article presents some basic answers to some of the most frequently asked questions with tapping birch trees, to the best of our current knowledge.
What is the Average Yield of Syrup be Per Tap?
As with maple, the amount of sap and syrup you can expect per tap will vary tremendously from tree to tree and from year to year. On average, it appears that a birch tree will produce between 10 and 20 gallons of usable sap per tap. The amount can vary greatly depending on when the tap is placed and the weather conditions that spring. We don’t yet have conclusive evidence regarding how the timing of tapping impacts overall yield, but there is concern that if you wait until the maple season is completely over before tapping birch trees that you could miss out on a substantial amount of early season sap flow (UVM is currently conducting research on this). It’s also worth noting that birch trees will continue to produce sap even as the leaves are coming out, and you need to know when to stop collecting sap. Just as the flavor of maple syrup changes when the buds are starting to swell, a similar phenomenon also occurs in birch. Towards the end of the season the sugar content of the sap decreases, bacteria and yeast build up to extremely high levels, and the sap is no longer usable for anything.
Although there is tremendous variation between trees and between sites, the average yield seems to be about .1 gallons of syrup per tap. One of the biggest factors that determines the syrup yield in the sugar content of the sap. An average tree seems to produce about a gallon of sap per day, but the sugar content can be as low as 0.1 or as high as 1.2 Most trees seem to be about .5 to .8 brix. At .5 brix, it takes about 175 gallons of sap to make a gallon of syrup, whereas at .8 it takes roughly 108 gallons of sap per gallon of syrup.
Does Vacuum Boost Yields?
None of our trials to date have shown a benefit of adding vacuum to a tubing system in terms of increased yield. In fact, the trees with individual buckets or bags have produced the highest yields in nearly every trial so far. However, tubing systems do greatly reduce labor costs and adding vacuum does allow sap to flow through the tubing faster, thereby increasing sap quality. It is unlikely any large scale birch operations will rely solely on individual bag or bucket collections, thus more research is necessary to understand how vacuum can best be utilized in a birch tubing system.
How does 3/16” tubing work with birch sap?
We did put out some trials with 3/16 tubing on birch trees on a steep hill and our results varied. Some of the trials produced abundant quantities of high quality sap. Because the sap flows so fast through a 3/16” diameter line, it came out the end of the line crystal clear, cool, and high quality. However, some of the 3/16” lines that we put in plugged up entirely with shavings from tapping the trees.
That is one of the main differences when tapping birch- unless you tap while its frozen before the trees are running, the sap will come out extremely fast as soon as you drill the hole and it will make the shavings extremely wet. They don’t come out as clean as when tapping maples, so one needs to wait for the sap flow to completely clean out any remaining wood chips before inserting the spout to the tubing system. We didn’t do that on all of our trees, and on the 3/16” lines this presented major problems with plugged fittings.
Does the size of the spout matter?
Many birch syrup producers use 7/16” spouts and all indications point to the fact that larger spouts will produce more sap than smaller spouts. We had some trees tapped with 7/16” spouts, and those greatly outperformed 5/16” spouts. We also experimented with 3/16” microspouts, but these produced far less than 5/16” spouts at all locations. We were interested in trying the 3/16” microspouts due to concern over internal stain columns from 5/16” or 7/16” tapholes. The idea was to see if we could get similar yields of sap with a smaller hole in order to do less damage- the differences in yields between the 3/16” and 5/16” holes were so stark that we will not be repeating this experiment again. However, more research is necessary to determine how much more sap 7/16” spouts provide over 5/16” with birch and the sustainability of using the larger spouts.
Should you plug tapholes at the end of the season?
Although nobody plugs tapholes in maple trees at the end of the season, it has been a common practice among birch syrup producers for many years. I didn’t understand why someone would want to do that until I saw what happens when you pull the spouts after you are done collecting sap. The sap will still continue to flow out of the tapholes, even as the leaves are appearing on the trees. The sap is an excellent growth medium of bacteria and yeast and you can often find large yeast growths on the tree from the dripping sap. However, the yeast growths eventually dry up and the taphole heals over, so we recommend letting nature take its course and have then tree heal naturally.
How Does the Birch Syrup Taste?
Birch syrup has a much different flavor profile than maple syrup and many sugarmakers do not like the taste of birch syrup. Yes, there is certainly plenty of off-flavored birch syrup out there, but there is also plenty of delicious, high quality birch syrup on the market as well. It’s much easier to make a good tasting maple syrup, but with skill, patience, and the right equipment you can also make very good tasting birch syrup. At the 1st International Birch Sap & Syrup Conference this past summer, we had many producers bring some of their birch syrup for people to taste and the results were incredible. Birch syrup is often dark and strong flavored, but depending on the processing techniques, it can also have a lighter color and much more mild flavor. If you have written off birch syrup based on a bad experience in the past, I suggest giving it a second try.