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.
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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.
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.
Though it is not well known, all species of walnut (Juglans spp.) produce a sweet sap that can be boiled down into valuable syrup. There is a well-established resource of black walnut (Juglans nigra) trees throughout eastern North America that could be utilized for syrup production to complement existing sugaring operations.