March 4th-March 17th

Waiting for warmer weather:  Roadside buckets in Caledonia County sit idle until the next run of 2017 sap. 

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.

A tale of two maple seasons:  A map depicting the accumulated Growing Degree Days (GDD) as of March 16th, 2017 shows how much closer southern maple producing states are to spring than northern parts.

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.


February 22nd-March 3rd

A mess of green tubing:  Lateral lines at the University of Vermont Proctor Maple Research Center lead to experimental chambers do not follow a typical tubing layout. 

Syrup production reached all parts of the state over the past week.  In general, producers who either by necessity (large operations) or choice (desire to catch early runs) were tapped and have reported a good season so far.  Some operations reported being a little behind during the prolonged period of unseasonably warm weather.  Some reports of mild to strong metabolism off-flavor have been received.  There have been a few reports (including one from Lamoille County below) of excessive mineral buildup on RO membranes.

Tree phenology is the study of seasonal and cyclical patterns of trees development.  Spring bud break is one of these patterns.  Unusually cold spring weather can delay bud-break whereas warm spring weather can accelerate the spring development of dormant sugar maple buds.  A long term set of observations (1991-present) and summary for sugar maple by the Vermont Monitoring Cooperative can be found here:

One producer from Bennington County reports boiling 2/19, 2/22, 2/23, 2/27 & 2/28.  The sap sweetness at this operation is reported to be low (1.5-1.7%).  Syrup produced has been Dark Robust.    This producer has reached approximately 20-25% of a regular crop at this location.  Other reports from Bennington County indicate similarly low sap sweetness and dark grades of syrup being produced.  It appears that producers who were tapped in January (some for the first time) were well positioned to catch sap runs in early February ‘did well’.

A Windsor County producer reports tapping was completed between 2/20-2/23 (in record time).  Very strong runs came during last week and again beginning the afternoon of 2/27.  As of 2/25 this operation was at about ¼ of an average crop and by 3/3 this yield had reached approximately ½ of an average crop.  This producer reports never having made ‘this much syrup this early’.  A little less than ½ of the syrup is Golden with excellent flavor with the balance being Amber.  The sap sugar content at this location began around 2% and has since dropped to an average of 1.6-1.7% by the ‘end ‘of the run.

Some sap flow experiments at University of Vermont, Proctor Maple Research Center are more complicated than others:  From 1964, ‘tree cut, space between trunck and stump dammed with plastic material, trunk put back in place.  Flow from trunk and stump recorded separately’.  J.W. Marvin, F.M. Laing, Claude Wagner and Floyd McLellan.   

A Rutland County producer reported tapping began on February 18th.  As of 2/27 tapping was nearly complete.  Good sap flow resulted in full tanks on 2/22.  First boil was on 2/23 with ‘nice Golden’ syrup having been produced.  Air temperatures reached 70F at this location on 2/25.  Sap continues to run with good vacuum (27” Hg) at this location despite a lack of cold temperatures.  This producer reports ‘all our snow has turned to mud’ during this period.

An Addison county producer with a relatively cold, northwest facing sugarbush reported finished tapping on February 19th.  First boil at this location was 2/23, with sap sweetness reported as 2.1% and very light Amber syrup (just below Golden in color) with excellent flavor being produced.  Boiling on the next two days (2/24-2/25) produced more good flavored Amber syrup with 2% sap sweetness on average.  A hard run of sap was reported on 2/28 at this location and sap sweetness holding at 2%.  Good flavored Amber syrup continued to be made.  Another strong run of sap into 3/1.  Sap sweetness has remained steady at 2% for this producer.  Good flavored Amber syrup continues to be produced at this location.  No off-flavors have been detected.  Total production at this location has reached approximately 1.6 pounds/tap.  This represents more than 1/3 of a crop for this operation.

A Washington County producer reports boiling two times by 2/27.  Sap averaged 1.8% and syrup grade was Amber with no off-flavors reported.  Tapping was 85% complete by this point.  Only patches of snow remained at this location (1200’ elevation).  3/1 brought this operation’s total yield to 0.5 pounds/tap.

One Lamoille County producer was 95% tapped as of 2/28.  First boil was 2/23 with another on 2/25.  First syrup produced at this location had a ‘very mild metabolized flavor’.  The off-flavor did not persist and all other syrup ‘has been fantastic flavor’.  Syrup grade has been Amber with color trended lighter with each barrel over this period.  This cold location still had plenty of snow on 2/28.  Sap did not flow well on 2/27.  A second Lamoille County operation reported very strong sap flow for the week 2/18-2/24. Sap sweetness 2.4% over this period.  This sap produced Golden syrup with no apparent off-flavor.  Yield was reported at 1.0 pounds/tap at this point with no off-flavors were detected.  As of 2/27 this operation had reached 1.28 pounds of syrup/tap (not quite ¼ of an average crop for this operation) Sap sweetness ranged from 2.0-2.5 over the five days 2/23-2/27.  This producer reports heavy mineral buildup on new RO membranes after only ‘just a little sap’ had been processed.  This producer was able to get flows back after acid washing.  The warm weather on 2/25 turned sap cloudy at this location.  Sap was clogging RO prefilters ‘just like it does in late season’.  Tapping was +95% completed as of 2/27 and expected to be finished by the end of the week.  As of 3/2 this operations syrup yield has reached 1.89 pounds/tap.  Very good sap flow averaging 2.3%.  ‘Very strong metabolism’ off-flavor was detected starting with syrup made on 3/2.  This operation boils sap from two locations and it was attempting to determine if one of the sources contributed to the off-flavor more than the other.

An Orleans County producer with roughly 3000 taps reports tapping began 2/19.  Deep snow (+3’) was estimated in the woods.  Sap was collected 2/23-2/25 and tested at 1.8%.  Boiling on 2/24 and 2/25 produced Amber syrup with no off-flavors reported.  A fresh coat of snow (6”) feel on 2/25.  Sap was running 3/1 at this location.  Tapping was expected to be finished on 3/2.

In Essex County, a producer reports tapping finished on 2/28.  First boil was on 2/24.  Sap sweetness was 1.7 and produced Dark syrup.  Sap was 2% on both 2/25 and 3/1.  Syrup was Dark on 2/25 and Amber on 3/1.  By this point, yields at this location had reached approximately 10% of a crop.  Syrup quality was ‘all nice’ and ‘no sand or nitre’ was reported.