Without a freeze, the flow of sap will continue to slow and eventually stop because there is no longer a difference between the pressure inside and outside of the tree. However, producers often observe an uptick in sap flow during the daytime over a few days. Why does this occur? Where did the extra sap come from? Typically, these short bursts of increased sap flow happen when the temperature warms over the next few days. The warm temperature causes gas bubbles in the wood fibers to expand and squeeze more water from the wood tissues, where it flows into the vessels and out through the taphole. This might occur for a couple of days, and eventually turn into slow weeping flows before ceasing entirely.
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Vacuum and gravity “pull” sap down lateral lines. Friction “uses up” energy. The energy that is lost in this case is vacuum (gravity is constant). Reducing friction in the tubing system preserves energy and preserves vacuum further up the line. If making tubing larger or smoother due to cost or implementation issues, the next best way to reduce friction in tubing is to reduce turbulence, especially at fittings. This can be readily achieved through two simple modifications. The first method is to incorporate a bevel into the entrance and exit of all fittings. The second modification is to incorporate an arc where sap streams meet.
Over the past five years we have examined several different approaches to reducing the restriction in sap flow from shallow tree rings in an attempt to increase sap yield and sugar content of collected sap. After exploratory research in 2018 and 2019, we settled upon a basic design starting in 2020 that in continued testing has proved successful. The two main features of this new spout include a shorter barrel and barbs.
Since 1958 the North American Maple Syrup Producers Manual has served as a basic reference source for the production of pure maple products. This 2022 edition provides up-to-date, science-based information and recommendations relating to all aspects of the industry. The guidelines presented will help users ranging from the hobby and beginning producer level to those well-established in the industry. In addition, the information herein will benefit foresters, land managers, Extension and outreach personnel, and others aiming to provide assistance to those in the maple industry. Numerous photographs, tables, a glossary and hyperlinks to selected source materials are included.
This publication is also available in print, at www.mapleresearch.org/ordermanual.
Because the impacts on yields of early tapping strategies, with or without subsequent rejuvenation, are likely to be affected by weather conditions which can vary widely from year to year, controlled experiments over multiple years are required in order to more fully assess whether any of these strategies result in greater yields than tapholes made during the standard spring sap flow period, or whether any increases in yield would be sufficient to compensate for the increased costs associated with implementing them. Thus, we conducted a multi-year, controlled experiment to assess the yields of several early tapping strategies, with and without subsequent rejuvenation, relative to the yields of standard spring tapholes.
This aim of this project was to determine whether early spout and dropline deployment before tapping could be used while maintaining good sanitation levels and high sap yields.
We regularly get questions from maple producers about which defoamers are the best to use. Of course, the answer is…it depends.
During the 2021 season, the UVM Proctor Center tested SapSpy (www.sapspy.com), a relatively new entrant in the sugarbush monitoring field.
In response to injury from wounds such as tapholes, trees initiate processes to compartmentalize the affected area in order to prevent the spread of infection by disease- and decay-causing microorganisms beyond the wound, and to preserve the remaining sap conducting system (Shigo 1984). This results in the formation of a column of visibly stained wood above and below the wound, and the affected zone is rendered permanently nonconductive to water and nonproductive for sap collection. These processes, along with effects from microbial activity, are responsible for the gradual reduction in sap flow from tapholes over the course of the production season. There has been recent renewed interest in strategies which attempt to extend the standard sapflow season or increase overall yields through the “rejuvenation” of tapholes. As part of a multi-year experiment to investigate the yields and net economic outcomes of several taphole longevity strategies, we conducted an experiment to investigate the volume of NCW generated in response to two of these strategies.
Maple producers know that when the temperature starts to rise in the spring, sap flows can’t be far behind. But when the weather starts to warm early in the spring and temperatures seem favorable for good sap flows, they are sometimes left wondering why the sap hasn’t started to run. There are several explanations for the disconnect between warm air temperature and a lack of flow during
the early season.