As February approaches, the question that is top of mind for most maple syrup producers in Wisconsin is when to begin tapping trees. There are variables to consider such as weather forecast, number of trees, method of sap collection (lines vs pails), and size of crew available to help.
Tapping trees last spring in the Rhinelander area was hard work. Not only was the snow deep, but there was an early wet snow followed by cold and then additional rounds of snowfall. The result was that some of the main lines were frozen deep in the snow. Part of our crew tapped trees while Logan and Lance dug out the frozen lines. The amount of ice between the lines and the ground gave them quite a workout!
This last weekend in January we have only about 6 inches of snow on the ground, so tapping trees is enticing. Our goal is to get all the taps in early enough to collect early sap, but not so early as to have reduced sap flow late in the season. Why would that happen? If trees are tapped too early, late season sap runs can be negatively impacted. Some maple producers call this drying. What actually happens is that bacteria, fungi or yeasts can grow in the tap hole in warmer temperatures. This growth combined with sap results in a thick substance that can block the hole. The warmer temperatures that support microbe growth tend to occur late in the season. Studies indicate that this happens more with trees tapped early than those tapped just before the season begins. However, the quality of late season sap can be variable, and tapping a little bit early has the benefit of collecting early season sap.
That still raises the question of how early is too early. The UVM Proctor Maple Research Center has conducted studies to understand what influences sap yield and maple tree sustainability. Based on their work, we think that tapping trees in February will enable us to have trees tapped and vacuums pulling sap through the lines to capture early sap flow without a negative impact on late season collection. Our lines are clean, and we will be using new taps.
Of course, we are still watching the extended weather forecast. Because we have lines, as trees are tapped the heat needs to be turned on in the pump houses and the vacuums are set to turn on when the outside temperature reaches 29 degrees. There is an associated cost for power, so a long run of very cold weather has cost without benefit of a sap run. It is a balancing act. I am sure it won’t be long before the scale tips on the side of getting out in the woods to begin tapping trees.