Palouse Maple Syrup 10-04-2011
Tapping Silver Maple Trees in Moscow, ID
Greg Hodapp, Landscape Maintenance Technician, University of Idaho, Moscow
Tapping Maples trees for their sap is an ancient practice going back thousands of years in the northeastern U.S., northern midwestern U.S., and eastern/maritime Canada. Though sugar maple is most commonly used in these areas, almost all trees in the Acer genus can be tapped for their sap including red maple, black maple, big leafed maple, and silver maple. Even box elder, whose syrup was known during early European settlement days as “mountain molasses,” can be utilized. My focus on this project was the Silver Maple (Acer saccharinum).
Due to its prevalence as a popular ornamental tree during the mid – 20th century silver maples can be found in the streets, yards, and farmsteads of virtually every town in the Palouse region including Moscow, ID. Elegant, hardy, fast growing, and adaptable to a wide range of growing conditions, this tree also makes for very good maple syrup. Having tapped maple trees in northern Wisconsin for many years in my own “sugar bush” (patch of maple trees) I have a deep love of tapping so when prime sap flow weather arrived in February 2011 in Moscow I decided to give Palouse-grown silver maples a try.
The reason behind my tapping specifically silver maples in the month of February is that these trees have a much earlier bud swelling period than most other maples. Sap flow is strongest just before and during bud swelling and tends to taper off after bud break. Also, days around 40 degrees F. and nights around 20 degrees F. are required for optimal sap flow. Freezing and thawing days and nights happen dependably in February in Moscow when silver maple buds are swelling. March and April however are a time when freezing and thawing days and nights on the Palouse do not happen with the same regularity. Sugar maple’s ideal sap flow doesn’t normally occur until mid-March to the end of April when their own buds are swelling so I wanted a tree genetically timed to start “waking up” a bit earlier. Hence silver maple.
Since the Palouse generally warms up a bit faster than the colder climates of the northeast and northern Midwest I postulated that tapping a tree species with early bud swelling in a region where ideal sap flow weather conditions happen earlier as well would make for much better tapping. The silver maples at my site started bud swelling the second week of February, this indeed happened to coincide with prime tapping weather. Thus I had the perfect combination of factors for desirable sap flow.
I obtained permission from the University of Idaho Farm Operations Manager to tape six mature 18”-36” DBH silver maple trees along Sixth Street by the Vandal Meats Laboratory. For tapping and sap collection I used food grade 4 gallon plastic buckets with lids, and 3/8” plastic tubing directly inserted into the tree instead of a normal tap or “spile.” This was a bit of a departure from tradition but I wanted to see if the tubing alone would suffice without a harder plastic or metal spile. A 16/32” hole (much smaller than normal), was drilled 1.5 inches into the tree about 2-4 ft up from the ground. The plastic tubing was inserted into the hole and ran directly into the 4-gallon bucket tied to the tree trunk.
All together over the course of 23 days in february and early march 35.75 quarts of sap were collected. This boiled down to 1.117 quarts of syrup (estimated to have about 65% sugar content- though I did not have a hydrometer). The sap to syrup ratio for these trees was roughly about 32 to 1 which is a very good ratio considering that the average sugar maple sap to syrup ratio is usually about 40 to 1.
The syrup was a light amber color and very mild with a slight citrus aftertaste, and without the usual slight pungent flavor of sugar maple syrup. Due to the small amount obtained we decided to just use all of it at a delicious pancake feed in the facilities’ grounds shop breakroom. It was great fun enjoying a locally made product usually so rare around these parts.
The results of this project, though they are highly preliminary and from a very small test population, seem promising. Good sap flow, a decent sugar content, and properly timed bud swelling and temperature fluctuations all add up to a decent Moscow/Palouse tapping season. Silver maples are prevalent almost everywhere and community tapping partnerships could act in concert to collect enough sap to make it worth everyone’s while. An alternate possibility may include planting silver maples as windbreaks as has been done before with success in the Midwest. According to the USFS “Silver maple has been planted as a farmstead windbreak in several locations in Minnesota. Its survival over a period of 38 years averaged 70 percent. Its height and diameter growth during the period averaged 11.6 m (38 ft) and 17.8 cm (7 in), respectively.”(1)
I believe that silver maple’s hardiness, adaptability and fast growth rate would make them an ideal windscreen tree, although probably in non-upland areas as their generally preferred growing sites are riparian soils- perhaps as waterway soil stabilizers. Farmers would reap the rewards of crop protection against wind and soil erosion and have the added benefit of tapping maple syrup in the springtime. Syrup prices west of the rockies are extravagantly high- up to 18 dollars a pint retail. Someone who could take advantage of this rare product in a local market would most likely do very well. At the very least I plan to tap again next February once the sap starts rising again.
(1) Silver Maple, Acer Saccharinum USFS Silvics Manual Online Vol. 2
Despite the ease of set up there was a one big detraction from using the plastic tubing. The union between the hole in the tree trunk and the tubing was not as strong as I would have liked- some sap leaked out in between. Next time I’ll go back to using a more traditional hard plastic or metal spile. Also, due to the weak connection, several tubes fell out of place during a prolonged absence. Probably a large amount of sap was lost.
35.75 quarts of sap were collected. This boiled down to 1.117 quarts of syrup, estimated to have about 65% sugar content. Sap collection was somewhat irregular, mostly according to how full the buckets were. A general synopsis of the season goes as follows:
Trees tapped on 2-10-11 had immediate strong sap flow
2-10-11 through 2-11-11
Strong flow, overnight low 20 deg. F. daytime high on 2-11 was 45 deg. F.
9.5 quarts of sap collected
2-11-11 through 2-16-11
Negligible sap flow, no freezing nights
2-16-11 through 2-19-11
Sap flow increased gradually, overnight lows averaged 27 deg. F. daytime highs averaged 38 deg. F.
7.5 quarts of sap collected
2-19-11 through 3-2-11
Gone for a week and a half
Four tubes became disconnected during absence
Overnight lows averaged 30 deg F. daytime highs averaged 40 deg. F.
12.75 quarts collected
3-2-11 through 3-5-11
Overnight lows averaged 28 deg. F. daytime highs averaged 39 deg F.
6 quarts collected