Vermont’s 2017 sugaring season is currently in a holding pattern due to cold temperatures and heavy snow that fell over the past week. The prevailing story before this cold period was how early the season began at many locations and shear length of time with above average temperatures. The past 8 days have seen below average temperatures and near record snowfall. It has been said that “an average is made of many numbers” sometimes the numbers that make the average are close together and sometimes they are all over the place. If the 2017 season in Vermont turns out to be ‘about average’, it will likely get there more like the latter.
The long period of above average temperatures had many asking about an early onset of spring and maple bud break. As mentioned in the previous Bulletin, the scientific study of climate and periodic cycles in nature is called phenology. The observation of spring bud development in maples is a form of phenology. The process whereby a given tree begins to exit dormancy is complicated, stimulated in large part by the accumulation of warm days. Growing Degree Days (GDD) is one measure that averages daily high and low temperature and subtracts it from an accepted base value. The base value can be different for different species (for maple, 32F is often used). Not all species will break bud at the same time since different species have different strategies related to spring activity and therefore have different requirements for accumulated GDD. The map below helps illustrate how parts of the maple world (more southern areas) have seen a very early end to the season whereas other parts (more northerly parts such as Vermont) continue to produce.
Spring tree phenology is more complex than accumulated GDD alone but it does help tell the story.
In Bennington County one producer reports poor sap flow over the last period. Sap sweetness was averaging 1.7 brix. Syrup produced was Very Dark/Strong Taste with no apparent off-flavors. Total yield at this location has reached 0.8 pounds/tap which represents about 35% of an average crop.
In Washington County a producer reports very good sap flow over the last period. The sap averaged 1.7 brix. Syrup produced has been Amber or Dark in grade with no off-flavors detected. Total yield has reached 0.93 pounds of syrup/tap.
A Windsor County producer reports very good flow of sap between 3/7-3/9. Sap sweetness averaged 1.8% at this location. Syrup produced was Amber with no off-flavors. Total yield at this location is now at 3.0 pounds/tap. This represents about 66% of an average crop for this operation. It sounds like others around the county have reached about 50% of an average crop.
One Lamoille County producer reports very good sap runs over the last period. Sap averaged 2.0% during this time. Syrup produced has been Amber with no off-flavor. Another producer reports making good flavored Amber (then lightening to Golden) syrup. Sap sweetness has been between 2.0-2.2% at this location. The total syrup yield is around 20% of an average crop.
In Orleans County a producer reports average sap flow over the last period. Sap sweetness was averaging 1.8% during this time. Syrup grade was Amber with no off-flavors reported. Total yield at this location was 1.1 pounds/tap. This represents 20% of an average crop.