Recent research . . . click here for relatively recent data on sap flow and sugar content of the sap of black walnut trees.
2015 was our second year making pure syrup from the sap of black walnut trees. We produced a bit of walnut syrup in 2016 and 2017 but as noted below we've backed off a bit as we've focued more on enhancements in our maple syrup operations.
During the 2013/14 season we were farmer cooperators working with Michael Farrell, Ph.D. (Henry II and Mildred A. Uihlein Director of The Uihlein Forest, Cornell University)
In that role of research cooperator, we harvested sap from ten black walnut trees and produced our first pure walnut syrup products.
Click here to see the findings of that research.
According to Farrell, "Sap flow in walnut trees was first reported in North America in the 19th century as part of a comprehensive study of sap flow in plants (Clark 1874).
"Sap flow in English walnut (Juglans regia) has also been studied in France due to the worldwide importance of nut production in this species (Ewers et al. 2001).
"Controlled research in an English walnut orchard and greenhouse demonstrated the capacity of autumn, winter, and spring sap flows through a combination of stem and root pressures. The researchers never investigated the potential to use this sap as a source of syrup production and there is no such data on potential sap yields and sugar content for tapping black walnut (Juglans nigra) and butternut (J. cineria) in the United States. The only research on using the sap of black walnut trees for syrup production took place in Kansas nearly a decade ago (Naughton et al. 2006). It was limited in nature and meant as a preliminary study; despite the promising results, no follow-up studies were conducted."
Since our efforts in 2015 and 2016 we've backed away a bit from the production of walnut syrup. It's really-really-really good...we love it, actually...but we've been more focused on improving our maple syrup operations and just haven't had the time to do it justice. We plan to pick it back up in the next few years so watch this space.