Comparison of the "small” Spout with the Traditional 7/16” Spout

The "small” spout, 19/64” or 5/16” in diameter, has been widely available to maple producers since the mid to late 1990's as a "healthy" alternative to the traditional 7/16” spout. While now in general use by producers in some regions, particularly those collecting sap by vacuum, the utility of these smaller spouts is still questioned by many sugarmakers, particularly those collecting sap by gravity. This article will review several studies conducted at the University of Vermont Proctor Maple Research Center comparing 7/16” spouts with small spouts (for the purposes of this article, 5/16”, and 19/64” will be considered equally as "small" spouts). These studies were designed to examine sap yields, end-ofseason drying, taphole closure and wounding (wood staining). While it is understood that even smaller diameter spouts are in use by some producers, as well as spout adaptors, and spouts made from non-plastic materials such as stainless steel, this research focused on common plastic spouts of the types offered by maple equipment dealers across the region. When the small spouts were introduced, the principal benefit of switching from a 7/16” to a 5/16” or smaller hole was thought to be a reduction in damage to the tree. The difference in cross sectional area of the two holes is considerable: a 7/16” hole is 0.152 sq. inches in area, while a 5/16” hole is 0.077 sq in. or approximately 50% less. Taphole closure, understandably, is more rapid with a smaller hole, and the use of a smaller drill bit allowed many producers to switch to battery operated drills for tapping with small spouts (these of course can also be used for larger tapholes, albeit less efficiently). Because there was less visible damage, some producers assumed that tapping guidelines should be adjusted to allow for tapping smaller trees. An assessment of internal damage, which requires destruction of the test trees, was necessary to answer questions about just how much less impact the small spouts have on the maples. This subject will be covered below. For most producers, the determining factor in whether or not to switch to smaller spouts is sap yield. Because the hole is smaller, it seems intuitive that less sap will flow from the hole. We tested this hypothesis in a number of studies over a period of several years, using both gravity (bucket) collection and vacuum collection methods.