Research Highlights 2003
PROCTOR MAPLE RESEARCH CENTER

FOOD SAFETY / SAP & SYRUP CHEMISTRY
Sources of Contamination in Maple Syrup: Lead can be a contaminant of maple syrup. Our goal is to reduce lead levels in syrup by identifying the sources of lead in maple equipment and altering production practices to reduce contamination of sap and syrup where it occurs. We are also interested in identifying natural levels of paraformaldehyde in maple sap (if any) and the influence of PF use on the level of formaldehyde in the finished product. Perkins, Wilmot, van den Berg USDA.

Adulteration of Maple Syrup: Several agents are used to modify the characteristics of maple syrup. Sometimes these treatments are part of normal sugaring operations that are used incorrectly, and thus become contaminants, and sometimes illegal substances are used to purposefully make syrup lighter in color. This line of research seeks to develop rapid screening tests to detect contamination or adulterants in maple syrup. Perkins, van den Berg, Baribault. USDA

PRODUCTION OF SAP AND SYRUP / MAPLE EQUIPMENT
Effects of Forest Fertilization on Maple Sap Volume and Sweetness: Fertilization is a common tool in agriculture to increase crop production. Other than anecdotal information from sugarmakers who do fertilize, little research is available to determine the long-term effects of fertilization on maple sugar production. This project examines the effects of fertilization on maple sap volume and sweetness, as well as tree health and growth, over a six-year period. Results indicate that fertilization may result in increased sap volume, but not sweetness, in forest stands of low-moderate nutrition. Perkins, Wilmot, Zando PRIVATE FOUNDATION, NAMSC

Evaluation of Small Spouts: This study compares sap production and wounding using normal and small spouts. Under most conditions, sap yield was roughly the same for either size spout using vacuum, but was occasionally a little less for small spouts with gravity flow. In large trees under gravity or vacuum, wood discoloration from small taphole wounds was significantly less than internal damage caused by large tapholes. Perkins, Wilmot, Stowe, van den Berg, Isselhardt CCMSMA, NAMSC.

Timing of Tapping and Length of Sap Season Using Small and Large Spouts: During the past decade, the northeast has experienced an unusual number of early spring thaws, with ideal sugaring weather sometimes occurring before mid-February. Starting in 2000, groups of trees at the Proctor Center were tapped with small and large spouts at three different dates in the spring in order to determine which timing maximizes sugar yield. Results varied from year-to-year, depending on the weather and snowpack. Data from the first two seasons suggest that under gravity, the longevity of tapholes drilled very early and fitted with small spouts is greater than that of larger (7/16") tapholes. Also, there were similar sap volume yields from trees tapped February I and March 1 in most years Wilmot UVM AES

Physical Differences Between Tubing Types: Tubing for sap collection, particularly 5/l6" tubing, is manufactured from a variety of plastics and carries many different trade names. We experimented with some of the properties of these materials, and we gathered information on advantages and disadvantages of various kinds of tubing from plastics manufacturers, equipment distributors and sugarmakers, with the goal of helping maple producers select the appropriate type of tubing for their woods. Wilmot UVM AES

Vented versus Closed 5/16" Tubing: It is widely recommended that tubing systems be closed rather than open or vented. While sap appeared to run faster through vented compared to non-vented tubing systems, venting of tubing resulted in a 32% loss of sap production, probably due to faster drying of tapholes and loss of natural vacuum on slopes. Stowe Isselhardt NAMSC

Optimum Number of Spouts per 5/16" Line under Vacuum: We compared sap production from tubing setups with 1,5, 10, and 15 spouts per 5/16" line. Single tap setups produced the most sap, with lesser amounts from the 10 tap (20% reduction) and 15 tap (28% reduction) lines. Stowe, Isselhardt, van den Berg NAMSC

New Versus Used Tubing Under Vacuum: Occasionally sugarmakers will recycle used tubing or delay replacement of tubing in their sugarbush. We compared sap production from new and old 5!l6" tubing. New tubing produced, on average over two seasons, 10-30% more sap than used tubing. Stowe, Isselhardt, van den Berg NAMSC

MAPLE PHYSIOLOGY & GENETICS
Relationship Between Tapholes on Opposite Sides of a Tree: Taphole guidelines were established in part because it is believed that tapping a tree below a certain diameter with more than one hole will result in decreased sap yield from each hole. To further our understanding of the way that an open taphole changes sap flow in the rest of the tree, electronic sensors that measure sap pressure at the taphole are being used to compare pressure on one side of a tree while a taphole is either open or closed on the opposite side. Trees of different diameters have been compared. Wilmot UVM AE

Fall Coloration in Sugar Maple: While important economically and scientifically, the process of fall coloration in sugar maple has not been widely studied. Our current research aims to improve the basic understanding of the process and identify factors that may be valuable in predicting the timing and quality of fall coloration. Specifically, anthocyanin pigments and their function and relation to physiological processes during fall senescence will be examined. van den Berg EPA

FOREST ECOLOGY & HEALTH
Potential Effects of Global Change on the Maple Sugaring Industry: This research is examining the potential effects of global warming on sap production in the northeast. A survey of sugarmakers will be conducted to find long-term records of production that might show evidence of global change. In addition, computer modeling will be employed to predict the effect of warmer spring seasons on maple flow. Perkins, Wilmot, Hoffmann USDA HATCH, NAMSC, DOE EPSCoR

Fern Effects on Sugar Maple Regeneration: Sugarmakers have long recognized that areas dense with hay-scented fern are often associated with poor regeneration of sugar maple. We compared sugar maple seedling survival of un-manipulated plots with plots that had ferns removed. Seedling survival is strongly correlated to fern density. Plots with high fern density had very low sugar maple seedling survival (and very low light levels), whereas plots with ferns removed had higher seedling survival (and higher light levels), whereas plots with ferns removed had higher seedling survival (and higher light levels). Removal may improve seedling densities in areas where regeneration is poor. Hane NAMSC

Questions? Send mail to: Proctor Maple Research Center, P.O. Box 233, Underhill Ctr, VT 05490 Phone: (802)899-9926, Fax: (802)899-5007, email: pmrc@zoo.uvm.edu, http://www.uvm.edu/~pmrc

NAMSC = North American Maple Syrup Council EPA = US Environmental Protection Agency
USDA = US Department of Agriculture CCMSMA = Chittenden Co. Maple Sugar Makers Association HATCH = USDA Hatch - UVM AES = University of Vermont Agricultural Experiment Station
VTFPR = Vermont Department of Forests, Parks & Recreation