There has been a lot of interest in 3/16″ tubing over the past several years. This article describes research results and possible future directions.
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The sugar concentrations and the volume yields of Acer saccharum Marsh. sap from trees with single tapholes both show large variations from year to year and during sap flow seasons. Daily measurements of sugar concentration and volume yield from 29 trees for 18 years show consistent patterns. High sugar concentrations and high volume yields are characteristic of some trees; lower sugar concentrations and smaller volume yields are characteristic of other trees. A regression analysis shows a highly significant relationship between sugar concentration and volume yield in individual trees.
A cost analysis of processing maple sap to syrup for three fuel types, oil-, wood-, and LP gas-fired evaporators, indicates that: (1) fuel, capital, and labor are the major cost components of processing sap to syrup; (2) woodfired evaporators show a slight cost advantage over oil- and LP gas-fired evaporators; however, as the cost of wood approaches $50 per cord, wood as a fuel would no longer have this cost advantage; (3) economies of scale exist in processing maple sap to syrup; (4) in 1977 the total cost of production, including both sap production costs and processing costs, for a medium-size (750) gallons of syrup) operation was $8.36 per gallon of syrup for oil-fired evaporators, $7.97 per gallon of syrup for wood-fired evaporators, and $8.37 per gallon for LP gas-fired evaporators.
The ALB poses a grave threat to maple trees, and to the maple syrup industry.
Sugarbush managers have long needed a guide for determining the stocking of their sugar maple stands. The question is: for desirable sugar maple sap production, how many trees per acre are needed? To provide information about stocking, the USDA Forest Service’s sugar maple sap production project at Burlington, Vermont, has made a regionwide study of the relationships between crown diameter and d.b.h. (diameter breast high) of open-grown sugar maple trees (Acer saccharum Marsh.). We found a strong relationship between crown diameter and d.b.h., and converted these data into stocking guides for various stand-size classes. The stocking guide are based on the assumption that trees with full crowns produce the best sap yields.
The current ‘traditional’ tap hole number guidelines involve adding a tap for each 5 inch dbh above 10 inches dbh. ‘Conservative’ guidelines involve placing one tap in trees 12 inch dbh and a second tap in trees more than 18 inches dbh. The reasons behind the traditional guidelines are not stated in the North American Maple Syrup Producers Manual, but the conservative guidelines are suggested when there is concern for tree health. The purpose of this article is discover where these guidelines came from and to re-establish the reasons why they exist.
The initial application of plastic tubing for gathering maple sap in the 1950s was indisputably one of the most significant technological developments of the maple industry in the twentieth century. However, the first viable tubing system was introduced over forty years earlier as a gravity drawn system made completely of metal.
Sap exudation refers to the process whereby sugar maple trees (Acer saccharum) are capable of generating significant stem pressure in a leafless state, something that occurs to a lesser extent in only a few other related species such as birch and walnut. This exudation pressure is what causes maple sap to flow from a taphole in sufficient quantities to be harvested and processed into syrup. Exudation has been studied for well over 100 years and has been the subject of many scientific studies, but there is as yet no definitive explanation for how such large pressures can be generated in the absence of transpiration (i.e., when no photosynthesis occurs to drive the flow of sap).
This article is intended to accompany the Tapping Zone Model available to download at the University of Vermont Proctor Maple Research Center (UVM-PMRC) website. It provides a general explanation of the model and how it can be used. The model can be used to estimate the chances of hitting conductive and nonconductive wood when tapping, and this can be used to assess the sustainability of current or planned tapping practices.
A model that calculates the proportions of conductive and nonconductive wood in the tapping zone of a tree over time given user-input values for tree diameter and tapping practices.