Everyone knows you can tap maple trees, boil down the sap and make maple syrup. Maple syrup on pancakes is a classic American breakfast. However, few people know that the same is true for other select species of trees. People in the sub-artic have for years tapped birch trees, both boiling the sap to make a sweet syrup and consuming it raw as a health drink. Walnut trees are on that list of those select other species. Members of the Juglans genus, black walnut (Juglans nigra), white walnut or butternut (J. cinerea) and English walnut (J. regia) have all been tapped for syrup production. This walnut syrup primer will get you on either the commercial or the hobbyist path.
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What I am proposing in this article is that woodland owners consider sap and syrup production as a way to increase the financial benefits derived from their forest resource by tapping their trees, and increase the fun in owning a woodlot with a good “sugarin off” party.
Black Walnut (Juglans nigra) is a tree to consider tapping, and Butternut (Juglans cinerea) has similar characteristics and can produce syrup. When considering tapping, however, it is good to understood that walnut trees and not just maples with compound leaves and big edible nuts. Walnuts have anatomical and physiological characteristics that affect tapping and syrup making.
Tapping walnut trees for sap collection and syrup production provides a syrup producer the opportunity to tap into the new, growing, and potentially lucrative specialty tree syrup market. The bulk price for walnut syrup in West Virginia this past season ranged from $150-$250/gallon, with retail sale prices topping $500/gallon (Tonoloway Farm, 2020). To get there, potential walnut syrup producers need to know how and when to tap their trees to maximize sap production. During the 2020 sap flow season, Future Generations University, with a grant from the NE SARE program, conducted studies looking at the application of vacuum, spout design, tapping procedures, and the timing of sap flow in walnut trees. This paper presents part of the findings of that work.
Details a study of 3/16″ tubing conducted in West Virginia.
During the 2019 sap season, Future Generations University, with funding from the West Virginia Department of Agriculture, began a series of tapping studies on tree species other than maple. We tapped and made syrup from black walnut trees. We had trouble developing the expected natural vacuum on the 3/16-inch lines, even though they had plenty of slope. We assumed that the problem was related to vacuum leaks associated with a poor seal in the soft wood with the minimally tapered spouts.
Our objective in this 2020 study was to revisit walnut tree sap flow and to determine whether vacuum applied to sap collection lines would substantially increase the production of walnut sap. Along the way, we made some somewhat startling and troublesome observations and formulated a next generation of questions that need to be answered to allow a viable walnut syrup industry to develop.
Accepted tapping practices for 7/16 inch spouts with no vacuum called for tap holes to be drilled 2-2.5 inches deep. Later practices for 5/16 inch spouts under vacuum, call for drilling the tree to a depth of 1.5 inches. The reason for the reduction in depth, was to reduce the occurrence of drilling into dead wood, especially on trees with a long history of tapping. This can lead to reduced sap yield. When the 2018 season left us with an unusually low sap yield, the question arose: does tap depth matter when the system is under vacuum?
This study showed that sycamore does produce a sweet sap flow that can be boiled down to roduce a syrup. That syrup had a nice taste, that some people say has a butterscotch like flavor. This is a new sap and syrup product, that will need more work to develop taping strategies that could lead to its commercial production. Likewise we need more information on the sap and syrup chemistry before we can provide guidance to potential syrup producers.
A 107 tap study area was established at John DalenÕs farm in Franklin WV. At this site we carried out a series of trials to learn about walnut sap flow, and to address sap and syrup production issues as they arose. We also collaborated with walnut sap producers in Palestine and Leon WV, and with Virginia TechÕs Catawba Sustainability Center in Blacksburg VA. The analysis section of this report is based on the work done at the Dalen farm study area.