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Yields from Early Tapping and Taphole “Rejuvenation” Strategies

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.

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SapSpy keeps tabs on the sugarbush

During the 2021 season, the UVM Proctor Center tested SapSpy (, a relatively new entrant in the sugarbush monitoring field.

Wound Response to Taphole Rejuvenation Practices

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.

Effects of Tapping Depth on Sap Volume, Sap Sugar Content, and Syrup Yield Under High Vacuum

Tapping depth strongly influences both sap yield and wounding. Numerous studies have focused on the amount of sap produced with ifferent depths, the most extensive work conducted by Morrow (1963), who found a tendency for increasing sap yields with increasing taphole depth. However, this work was conducted on gravity with 7/16” tapholes, so is less informative to most producers using 5/16” spouts and vacuum.

Darkening of Maple Syrup in Uncoated and XL-Coated Plastic Containers

Although several previous studies have examined syrup darkening in different retail containers, packers and producers sometimes question the effectiveness of an oxygen-barrier in reducing the rate of color change. Two studies were performed by the University of Vermont (UVM) Proctor Maple Research Center (PMRC) in 2018 and 2019 to compare the rate of color (LT) change in maple syrup in uncoated and XL-coated retail plastic containers.

Tapholes: Straight or Slanted?

Is there any difference in sap yield when tapping at a slight angle (the historical recommendation) or tapping straight in (the current recommendation)? While there might be other considerations suggesting that tapping straight in is advantageous, from a syrup yield perspective, there is no apparent difference.