The Vermont Maple Minute is a podcast hosted by Mark Isselhardt, University of Vermont Maple Specialist, Proctor Maple Research Center.

 

Transcripts of Podcasts

 

Sugarbush Health

Exotic Earthworms

Gardeners know that earthworms can be beneficial for growing vegetables and flowers by helping with soil aeration and producing fertilizer through their castings.  Sugar makers may not know that earthworms and relatively newer invaders the so-called “crazy snake worm” pose a significant threat to their sugarbush.  Worms in the northeastern US are exotic and some are invasive meaning they can become established and disrupt the native species present. Earthworms can effect changes in the forest soil making it difficult for native plants (such as sugar maple) to survive. The worms can disrupt the lifecycle of certain plant species browsed by animals which leaves the remaining tree seedlings the only food source available.  Long term risks for our native hardwood forests are a concern for foresters and natural resource professionals alike.  There are no recommendations for removing established worm populations and research into the changes in forest ecosystems is ongoing.  Recommendations are focused on preventing these organisms from being established in the first place.  Another important consideration is to avoid bringing soil or other organic matter from other properties. 

Fall Color

Autumn colors in leaves of maple trees is an annual phenomenon that is highly prized for its beauty and is also economically important.  As day length shortens, the tree stops making new green chlorophyll pigment while the chlorophyll already in the leaves breaks down.  Without the green to mask it the yellow and orange carotenoid pigments become more visible.  In some species like maples, red anthocyanin pigments are actively produced around this time.  Research results suggest that the production of red pigments might help plants by protecting leaves while they reabsorb nitrogen before the leaves fall.  There is no foolproof way to predict how the fall foliage season will progress.  The intensity of color can depend on many factors but it is generally understood that cool weather creates the conditions that produce more vibrant colors but that freezing temperatures can cause those colors to fade.  The weather on a given day can also impact the perception of color as well as the mix of species present and the topography of a particular location.

Forest Tent Caterpillars Update

It appears as though the recent widespread defoliation event related to forest tent caterpillar has ended.  According to the Vermont Department of Forest Parks and Recreation, there have been no reports of defoliation attributed to this native insect in 2019.  This is in stark contrast to the roughly 70,000 acres of defoliation mapped in 2018.  The dramatic decrease is typical of the “boom and bust” cycles previously observed.  Cycles will usually last between 2-4 years in Vermont and occur roughly every 10-20 in some part of the state.  The caterpillars can multiply rapidly and make their presence known by consuming large volumes of leaf matter.  During the outbreak, it is not uncommon for wide areas of forest to appear brown and almost leafless from afar.  The vast majority of trees will regrow new leaves to make up for the ones that have been lost.  In rare cases some individuals have even been defoliated twice in the same summer without dying.  At the end of an outbreak the caterpillar populations will crash as a result of a corresponding increase in several natural predators and natural controls.  Most trees will recover after a few years of poor growth and this native insect will return to relative obscurity until the next outbreak. 

International Maple Syrup Institute

This is Mark Isselhardt, Maple Specialist with University of Vermont Extension and this is another Vermont Maple Minute.
The International Maple Syrup Institute (IMSI) was founded in 1975 to promote and protect pure maple syrup and other pure maple products. Its mission remains largely unchanged:  The organization provides an important international framework for communication, information exchange, and cooperation on a variety of issues related to the production, sale, and marketing of pure maple syrup. In addition, the Institute has been a strong monitor for adulteration around the world, protecting the integrity of maple products.  The three key parts to IMSI’s mission are: To protect the integrity of pure maple syrup.  To encourage more industry cooperation and to improve communication within the international maple syrup industry.  The IMSI also devotes considerable time and effort towards advocacy on regulatory issues at both the state and federal level.  One recent significant effort was to advocate against the planned requirement that all sugar found in maple syrup be listed as “added sugar” on the FDA nutrition facts panel.   
This is Mark Isselhardt, Maple Specialist with University of Vermont Extension and this has been another Vermont Maple Minute.

Late Season Defoliators

As late summer progresses so-called late-season defoliators are beginning to become visible in Vermont woods.  Two such insects are maple leaf cutter and maple trumpet skeletonizer.  The first report of damage from maple leaf cutter was in 1911 when this insect was responsible for defoliating 25 acres of sugarbush.  Maple leafcutter larvae cut about a ½” diameter round hole in sugar maple leaves.  The feeding begins as leave mining then takes place under the protection of a disk of leaf material.  As the larvae molts it moves to a fresh section of leaf uses a larger and larger disk.  Mortality of overstory trees is rarely associated with this insect but occasionally understory maples could die as a result of the severe injury.  Maple trumpet skeletonizer is found primarily on sugar and red maples.  Their larval stage feeds on the underside of leaves, between two major veins.  As the larvae grow they form a long, dark tube of its own waste or frass, inside a slightly folded leaf.  By the time the leaf damage has become widely visible trees will have produced a majority of their energy for the summer and upcoming winter and while unsightly, these two native insects are not responsible for significant impact to the host trees health and vigor.   

Maple Seeds

Sugar maple flowers that are fertilized in spring, will develop into mature seeds in late summer.  The seeds come in the form of winged samaras (sometimes referred to as helicopters or whirligigs).  Sugar maple samaras develop in pairs but generally, only have one viable seed per pair.  In late summer of heavy seed years, tree crowns can appear brown as the wings change color from green to tan or brown.  The wing shape allows for the seed to travel 100 yards or more beyond the parent tree, which in turn increases the survival rate and genetic diversity of the species.  Maple seeds germinate at around 34 degrees F.  This is one of the lowest germination temperatures of all forest trees and germinated seed can regularly be found before the snow disappears.  Sugar maple is generally very successful at germinating, with roughly 95% success rate.  But just because a seed germinates doesn’t guarantee it will grow to become a tappable tree.  Less than 50% of all seedlings survive the first year and since many species of wildlife enjoy the seeds as a food source, the numbers go down from there.   

North American Maple Syrup Council

This is Mark Isselhardt, Maple Specialist with University of Vermont Extension and this is another Vermont Maple Minute.
The North American Maple Syrup Council is an international organization, founded in 1961.  The purposes of the Council are to promote research in the chemistry and technology of maple sap and the products derived from it; in sugarbush management and disease control and in marketing of maple products and standardization of the maple products.  The Council has grown since the acceptance of its first six charter members in 1961. It now represents the majority of maple producers and maple production throughout North America, counting 15 of the 16 largest producing states and provinces as members.  Among its many duties, the council is responsible for publishing the Maple Syrup Digest and for awarding grants to deserving research projects related to maple production.  An annual meeting, held jointly with the International Maple Syrup Institute, rotates between all member states and provinces and includes technical sessions that discuss the most recent research and the international maple syrup contest.  Vermont last hosted the meeting in 2016.   
This is Mark Isselhardt, Maple Specialist with University of Vermont Extension and this has been another Vermont Maple Minute.

Photosynthesis

The sugaring season has been over for a while.  Maple trees ended their annual period of dormancy when their winter buds broke, allowing new leaves to emerge.  These lush green leaves are now working to produce all the energy needed for the tree to grow and survive.  Photosynthesis is the complex series of chemical reactions that combine, water, carbon dioxide and sunlight to produce energy in the form of glucose.  The maple tree, like all green plants, produces this sugar to satisfy its immediate needs such as feeding living cells and growth but also to store for future needs such as winter dormancy, seed production and defense from disease.  Trees convert the sugar to starch for long term storage with the help of enzymes and convert it back when needed.  A portion of this same stored energy is what sugar makers collect in sap each year.  When growing conditions are favorable, maples will produce an abundance of stored energy and likewise, those stores will be reduced when trees don’t have adequate water or have limited exposure to sunlight.  Most years’ maple trees in Vermont are healthy but when one or more stresses impact an individual, dieback and decline can occur.

Saplings (aka Wounding)

In 2010, University of Vermont researchers Timothy Perkins and Abby van den Berg initiated experiments to collect sap from small maple saplings.  The saplings were roughly two inches in diameter.  This method involved cutting the stem in the spring to expose fresh xylem tissue and then applying vacuum to extract the sap.  These saplings don’t die but they do rely on dormant buds in order to establish a new set of twigs and leaves after the maple season is over.  Saplings can be used repeatedly but fresh wood needs to be exposed and 8-10” of wood must be cut off to get to that fresh wood.  Although tapping for sap collection does create a small wound in the tree and result in some loss of sugar to the tree, maple syrup production is considered a sustainable agricultural practice.  In many cases trees have been tapped by several generations without noticeable harm.  Maple producers typically follow tapping guidelines which allow for a certain number of taps based on the size and the health of the tree.  These guidelines can be modified to account for drought, defoliation or other stress factors that might impact tree health.  

Shade Tolerance 1

All green plants, which includes trees, need sunlight to produce energy for survival.  Some trees can satisfy their basic needs with less light than others.  Sugar and red maples are two examples of such trees.  They are both considered shade-tolerant; with sugar maple being more shade tolerant than red maple.  This means a sugar maple can survive with less light for longer amounts of time than other species.  This ability isn’t simply making more with less it’s also about using less energy.  For example, sugar maple can survive in the understory on just a few percent of full sun for years and can reach their maximum capacity at just 25% full sun.  Shade tolerance is not the same as shade loving however.  This is an important distinction since even though a given tree can survive for decades in the understory it doesn’t mean it prefers to do so.  The longer a tree has to endure living in a low light environment the less likely it is to respond with and if a gap in the canopy opens.  To avoid this, make sure the forest management plan for a given property is written and followed to ensure regular thinning to produce adequate light.  

Shade Tolerance 2

A trees form, the size and shape of its stem and crown, will be impacted by living in a low light environment such as the forest's understory.  So-called suppressed trees are able to capture just enough sun to survive.  Sugar maples growing in the understory tend to leaf out earlier than the trees in the upper canopy.  When measured, it has been shown that these understory trees will produce as much as 80% of their entire annual food production in that short period before the canopy closes in and light becomes more limited.  Perhaps the most visible impact of a tree being suppressed for a long period of time is a characteristic “flat topped” crown.  This results from the tree growing attempting to get sun from the sizes rather than from above.  Trees whose branching has been impacted this way will have a harder time responding if a gap in the canopy were to open up.  These poor formed individuals will generally not mature into large, tappable trees.

Sugar Maple Seeds

Sugar makers and community members alike have noticed a large number of sugar maple seedlings this spring.  These first year trees were the result of a large seed year in 2019.  Sugar maples begin producing seed when they are about 40 years old or 8” in diameter.  Trees produce some seed every year but exceptionally large amounts of seed every 2-5 years.  Seed production becomes greater as the tree grows and mature trees can produce thousands of seeds in big years.  Mature stands of sugar maple are capable of producing millions of seeds per acre.  Maple seeds are winged and produced in pairs, also known as samaras.  Usually only one side of the sugar maples double samara seed is viable.  When the seed is ripe (after about 12 weeks) it is dispersed by the wind by as much as 300’.  Maple seeds are an important source of food for wildlife.  Sugar maple seeds have a high natural rate of germination and need temperatures just above freezing for 35-90 days in order to start growing.  Of the seeds that do germinate, only a very small percentage will survive the first year.

Sugarbush Management1

Sugar makers rely on healthy, abundant maple trees to provide sap each spring.  Taken together a group of maple trees managed for sap collection is called a sugarbush.  Developing a healthy, productive sugarbush takes time and effort.  Forests are highly competitive environments with trees vying for water, nutrients and perhaps most of all, light. To maximize sap production, decisions need to be made about which trees to cut and which trees receive more light to grow.  Choosing which trees to save and which to cut can be difficult, however, growth of all trees will not reach their potential if allowed to be overcrowded.  Maple trees with the best form, a lack of significant decay or other wounds and a deep, healthy crown will grow fastest and produce the most sap.  Retaining at least 25% none sugar maple in your woods will help reduce the impact of maple pests and create a more robust forest ecosystem.  

Sugarbush Management 2

Late summer, while leaves are still green is a good time to assess the trees in your sugarbush.  Weak or declining individuals will show areas of crown dieback.  Trees with more than 75% dieback will likely not survive but are still competing for light, water and nutrients with healthier crop trees and should be considered for removal.  Flagging potential trees to cut is a good way to plan what needs to happen.  Remember that doing a little overtime is better and has less risk of damaging the sugarbush than doing the work all at once.  Trees that have grown up with other trees for support and lack a strong root system need time to adjust to the increased growing space.  Individuals could be lost to wind or be subject to root damage and sunscald if too many adjacent trees are removed all at once.  Opening 1 or 2 sides of a given crop tree balances the benefits of increased light while reducing the risk of a catastrophic loss.  Above all, remember that safety is the number one priority when working in the woods.

Sugarbush Value

The recent period of expansion in the maple industry has seen both established operations grow and many new operations start from scratch.  Some real estate listings of land include estimated potential taps.  But how many of those taps are actually economically feasible to collect from?  What are the important questions to ask before making an offer on a parcel?  There was a time when the number, size, and density of tappable trees were the most important consideration for a sugar maker looking to purchase more property.    Traditionally, a sugarhouse would be centrally located on the sugarbush so as to lessen the distance traveled when hauling sap.  While the number one consideration when looking at a parcel of land is still the trees, sugar makers today often find themselves faced with several other important aspects of the property before making an offer.  Some of the more common issues facing modern sugar makers are: Access to power, quality of road network, distance to improved road and topography.  Like most real estate transactions, it comes down to an issue of value.  In other words, does the asking price fairly reflect the value of the parcel for the purchasers intended use.  

Thrips

Pear thrips is a species of insect that while native to Europe and Eurasia has been present in the United States for over 100 years.  This insect is slender and brown as an adult and just over one mm long with delicately fringed wings.  Thrips were first noticed as a pest in Vermont sugarbushes in the 1980’s when significant damage was observed statewide.  Adults emerge from underground in spring, usually in April.  The damage caused by thrips mostly appears as “leaf tattering”.  It has also been described as being like making paper dolls since the damage done isn’t fully known until the leaves unfold.  This damage is the result of larval thrips injuring very young leaf tissue as they feed on plant juices before leaves have fully developed from the winter bud.  It appears that greater damage is caused when adult emergence corresponds to bud break and especially when cool spring weather delays the rate of leave expansion.  Despite weather conditions in 2019 that might have contributed to increased thrips damage luckily no reports were received.

Vacuum and Minerals

A modern maple operation relies on a tubing system with vacuum to maximize sap production.  The innovation of plastic tubing originally came as a labor-saving device and not to increase sap yield from individual trees.  As the materials used to produce maple tubing became more robust and vacuum pumps were employed, the increases in sap yield became obvious.  There are many questions about how the use of vacuum tubing does or does not impact the tree or the sap harvested from the tree.  Research done at the University of Vermont Proctor Maple Research Center sought to answer some of the common questions.  To answer the question if the naturally occurring concentrations of minerals change as more vacuum is applied to the tap hole, groups of trees were tapped and exposed to various levels of vacuum ranging from 15” to 25” Hg (inches of mercury, a unit also used in weather reporting, is a measurement of vacuum).  A control treatment with no applied vacuum was also included.  Samples of sap were collected through the season and analyzed for the most abundant, naturally occurring minerals in sap.  The results indicate that compared to sap collected using vacuum had similar concentrations of calcium, phosphorus, potassium, magnesium, iron and manganese compared to gravity collected sap.  As with many experiments, the results lead to more questions and the need for additional research

Vacuum and Wounding

A modern maple operation relies on a tubing system with vacuum to maximize sap production.  The innovation of plastic tubing originally came as a labor-saving device and not to increase sap yield from individual trees.  As the materials used to produce maple tubing became more robust and vacuum pumps were employed, the increases in sap yield became obvious.  There are many questions about how the use of vacuum tubing does or does not impact the tree or the sap harvested from the tree.  Research done at the University of Vermont Proctor Maple Research Center sought to answer some of the common questions.  To answer the question if the internal wounding associated with tapping is larger when more vacuum is applied to the tap hole, groups of trees were tapped and exposed to various levels of vacuum ranging from 15” to 25” Hg (inches of mercury, a unit also used in weather reporting, is a measurement of vacuum).  A control treatment with no applied vacuum was also included.  After the season was completed the trees were felled and the size of the tapping wound was quantified.  The results indicate that the size of the wound was no different in trees tapped with or without vacuum.  As with many experiments, the results lead to more questions and the need for additional research.      

Water Bars

Access to a sugarbush is critical for installing and repairing sap collection equipment, tapping and managing crop trees and responding to the effects of natural disturbances.  Quality access to the sugarbush relies and a road and trail system that can handle the appropriate vehicles needed in the operation at all times of year.  Trails and roads must also be designed to handle significant precipitation events without washing out.  When designed and installed correctly, water bars are a critical investment in preserving the trail and road system.  Water bars divert water from the road before it can pick up speed and erode the road surface. There are a few key elements to correctly installing water bars.  The cost of repairing significant road damage far exceeds the costs of installing and maintaining water bars.  The slope of a road or trail will determine the spacing between water bars; the steeper the slope, the more water bars are needed.  A typical water bar will consist of a channel dug somewhere between 8-10” deep with a downhill berm of approximately equal height that completely crosses the road.  Water bars that do not cover the entire width of the trail will allow water to pass.  To be effective, water bars must not be installed at right angles to the road, 30 degrees is ideal.  The end of the water bar will empty out into a runoff area and allow the water to settle.  Keeping the water bars free of leaves, silt and debris will ensure it’s ready to function when needed.        
This is Mark Isselhardt, Maple Specialist with University of Vermont Extension and this has been another Vermont Maple Minute

 

Sap/Syrup Production

2020 Crop Report

Reports of above average syrup production have been common across Vermont in 2020.  Sugar makers report excellent quality syrup being produced throughout the season.  In general, March was slightly above average for temperature and April was below average.  Large or relatively small impacts on total yield depended on operations location, aspect, tapping schedule and collection process.  At the University of Vermont, Proctor Maple Research Center, sap sweetness over the past 15 years has been just over 2%.  The sap collected in 2020 was approximately 12% below average.  This is coming on the heels of 2019 where sap sweetness was about 5% above average.  Sap sweetness is not the only thing that determine total production.  In fact, most producers who reported below average sap sweetness still reported good syrup production.  A significant run was reported across the state at the end of March.  In general, March was a key month for production as the cool weather of April 2020 did not have as many quality days of sap flow.  Isolated reports of below average production have been received but are limited to producers in lower elevations and warmer areas, those whose tapping was delayed or due to equipment issues.  The official crop report which is the product of sugar maker surveys, will be released by the USDA sometime in the first half of June.

Bulk Syrup Sales

According to the 2019 USDA NASS maple syrup report approximately 90% of Vermont’s total annual maple syrup production (about 1.8 million gallons) was sold into the bulk market.  The remainder of the crop was sold either to retail or wholesale customers.  This represents a significant change over less than 20 years.  In 2002 the Vermont crop was estimated to be less than 500,000 gallons of syrup.  Approximately 60% of that crop was marketed as Bulk.  The increase in bulk syrup sales can be tied in large part to the recent expansion of maple production and the types of operations fueling that expansion.  The majority of additional production came from increased taps in existing and new operations with tap counts of 10,000 or more.  Over the same time period of 2002-2019 there was a nearly 10% increase in the number of these operations.  The business of making maple draws entrepreneurs of all kinds.  Some produce syrup as a hobby to share with friends and family, others will count on their annual production for an important part of their annual income and for others, maple represents their entire annual income.  Whatever the scale of operation, the quality of syrup sold directly to consumer must meet the high standards set forth by the Vermont maple law.

DE Filtering

Just as the sugars found in sap become concentrated during boiling, so too are the naturally occurring minerals found in sap.  As the concentration of minerals increases in the sap, it approaches, then exceeds the point of saturation.  When that happens, sugar sand which is a precipitate made primarily of calcium, forms and gives syrup a cloudy appearance.  Syrup coming directly from the evaporator is therefore cloudy and must be filtered before being stored in a barrel or bottled for consumer use.  One way of removing sugar sand from syrup is with a pressure filter.  These devices are used in many industries and rely on a pump to force syrup through filter media.  The most common filter media is food grade diatomaceous earth (also known as DE).  Make sure to follow the recommended guidelines for handling DE.  DE is the skeletal remains of single-celled plants called diatoms.  These microscopic algae come in many species and differ depending on if they lived in fresh or saltwater.  DE appears like a white powder.  Under extremely high power magnification, diatoms have many complex shapes, some like sand dollars, baskets or other sieve-like shapes.  It is the secondary pores found on each individual DE particle that captures the fine sugar sand and produces a syrup that sparkles.  

Heat

Processing sap with heat in the evaporator is essential. The reactions responsible for the development of maple syrup’s characteristic color and flavors require heat to proceed.  Syrup produced by methods with little or no heating, such as freeze‐drying or vacuum distillation, is nearly colorless and flavorless.  The starting sap has the biggest role to play in what type of syrup is going to be produced on that day.  Producers equipment can have an influence.  But by and large, it is the sap you have on that what which will determine the syrup you will produce.

Hydrometers

The Vermont maple law requires packaged maple syrup have a density of between 66.9 and 68.9 degrees Brix.  Brix is a measure of sugar concentration in a pure sugar solution.  Although we know there are other many dissolved minerals in maple syrup their concentration is low enough to allow the Brix scale to be used.  In order to know if syrup is within the legal range of density a sugar maker must take measurements.  The most common instrument used by sugar makers for measuring density is called a hydrometer.  A hydrometer is a precisely graduated scale inside weighted glass bulb with a thin stem.  The hydrometer will float at the correct number when the syrup is the correct density.  The hydrometer will float higher or lower depending on the syrup temperature so knowing the temperature of the syrup is critical to getting accurate measurements.  Hydrometers are fragile and if damaged will not produce accurate readings.  Be sure to have at least one extra in the sugarhouse and have your hydrometers tested annually.  

Invasive Earthworms

Gardeners know that earthworms can be beneficial for growing vegetables and flowers by helping with soil aeration and producing fertilizer through their castings.  Sugar makers may not know that earthworms and relatively newer invaders the so-called “crazy snake worm” pose a significant threat to their sugarbush.  Worms in the northeastern US are exotic and some are invasive meaning they can become established and disrupt the native species present. Earthworms can effect changes in the forest soil making it difficult for native plants (such as sugar maple) to survive. The worms can disrupt the lifecycle of certain plant species browsed by animals which leaves the remaining tree seedlings the only food source available.  Long term risks for our native hardwood forests are a concern for foresters and natural resource professionals alike.  There are no recommendations for removing established worm populations and research into the changes in forest ecosystems is ongoing.  Recommendations are focused on preventing these organisms from being established in the first place.  Another important consideration is to avoid bringing soil or other organic matter from other properties. 

Measuring Syrup Density

Most people know that to make maple syrup you have to do a lot of boiling.  You collect the sap from the trees and you evaporator the water while concentrating the sugars.  You might not know that to determine if you actually have correct density syrup you need to do some measurements.  In the old days, people would use their scoop from their evaporator and carefully look at how the syrup behalves as it flows over the edge of the scoop.  Correct density syrup will form a bit of an apron or a thin film and it will look just right when the syrup is correct.  Most sugar makers now use a combination of thermometers to make temperature measurements and what’s called a hydrometer, which is a way of measuring density.  In Vermont, legal syrup has to be between 66.9 and 68.9 percent sugar.  To find out if their batch of syrup is correct, sugar makers will use a hydrometer (which is a calibrated glass instrument) that will float in syrup and has precise graduations along the stem of the hydrometer.  The hydrometer will float at the correct line when the syrup is correct density.  It’s important that sugar makers know the temperature of the syrup when they are using a hydrometer because hot syrup will float lower than when the syrup is cold.  Assuming the sugar maker does all these things correctly, they will have a very good idea of the precise density of the syrup.  And when it’s correct they will put it in a barrel or a retail container and it will be available for sale in the marketplace.

Mid-March Update

The sap flow has ramped up across the state over the past week with producers reporting having 30-50% of their expected crop, whereas in the colder locations around Vermont the numbers are still less than 25%.  The forecast looks good for much of the state over the next week with temperatures remaining cold enough at night to allow for some recharge of sap.  Areas to the south of Vermont have reported good yields for producers who were tapped and ready when the ideal sugaring weather arrived.
A Rutland County sugar maker reports sap running very well over the past week, with sap sweetness averaging 2%.  Syrup produced with this sap has been graded as Amber/Rich with no off-flavors detected.  Total production has reached 50% of the anticipated crop as of 3/10.
A sugar maker in Orleans County reports finishing tapping on 3/8.  Sap flow was average over the past week and sap sweetness was 2%.  Syrup produced was Amber/Rich with no off-flavors.  The operation has reached 2% of the expected crop and this producer offers that it’s “nice to have sap running in March.”
In Essex County a producer reports sap running very well over the past week and sap sweetness at 2%.  Syrup produced over the last week was Dark/Robust with no off-flavors.  Total production has reached 7% of the anticipated crop.  This sugar maker added the following:
“Last year I didn’t make syrup until Late March. This year we started early march.”
Barring any significant and extended warmups the 2020 crop looks to be a good one.  The final tally won’t be known for some time.

Organic Maple Syrup

Certified organic maple syrup is produced by many Vermont maple producers and generally commands a higher price in the marketplace.  In order to legally market your syrup as “organic” an approved third-party certifier such as Vermont Organic Farmers must inspect all aspects of your operation.  What makes one operations syrup organic and another does not have more to do with the process of making the syrup than with the final product.  The application and inspection process will determine if all the requirements have been met and if sufficient record keeping is done to trace a given container of syrup back to the day it was produced.  The keys to certification include documenting that cultural practices are being followed to ensure a healthy, diverse forest ecosystem and that no synthetic materials are used in the production of sap or syrup.  Additionally, certified organic maple operations must adhere to a specific set of tapping guidelines, forest management, and syrup production practices approved by the particular certifier.

Reverse Osmosis

Some producers use membrane separation (called “reverse osmosis” or simply “RO” within the maple industry) in addition to evaporation with heat. In this process, sap is forced through membranes that have pores which are large enough for water to pass through, but are too small for sugar molecules.   Sap can be concentrated to between 8 and 15% sugar (which removes 75 to 90% of the water) prior to heating in the evaporator.  Use of membrane separation substantially reduces the time and fuel required for the evaporation process in a maple evaporator, and thus can greatly increase the efficiency and profitability of syrup production.

Sanitation

Like people, plants   have   strong   mechanisms   to prevent the spread of microorganisms within their tissues.  Trees are capable of “walling off” wounds to prevent infections from spreading throughout the tree.  This healing process also slows, and eventually stops, the flow of sap from tapholes.   By using good tapping sanitation practices such as replacing spouts each year, periodically changing portions of the tubing system, using good tubing cleaning procedures, or using check‐valve spouts, maple producers are able to achieve significantly higher sap yields from trees by delaying the response to wounding.  The response from wounding does eventually take place generally at the end of the maple season when the leaves start to come out and the tap hole closes off for good.  

Spouts

Although bucket spouts are still available, most spouts used in the maple industry currently are plastic and designed to be used with vacuum.  Spouts are constructed of food‐grade nylon or polycarbonate and are smaller in size (5/16” diameter)  than  earlier spouts.  Increasingly, spouts are generally intended to be used for one season, and are then disposed of or recycled, and replaced with a new spout each season to   minimize   reductions   in   sap   yield   caused   by microbial contamination. Spouts are generally one piece, but may also be made in two parts, referred to the stubby (tubing end) and adapter (tree end), which are mated together when in use.

Syrup Is Complex

Compared to the relatively simple composition of maple sap, maple syrup has over 130 different identified flavor and aroma compounds.  The predominant classes of flavor compounds are phenolics, pyrazines, and carbonyl‐based compounds. Typically, lighter‐colored syrups tend to contain lower levels of flavor compounds than darker syrups.  Sap collection techniques, time of season, sap storage conditions, sap processing methods, and packing all play a role in determining the chemistry resulting in the perceived flavor of the finished product.

Tapping

Winter is almost over and spring is almost here; it’s time to make maple syrup.  Each season sugar makers have to drill a new hole if they want to collect sap.  The reason for this has to do with how trees respond to wounds.  When a hole is drilled into the stem of a tree, the tree responds to the wound and produces a barrier inside to prevent large infections from taking place.  This process is called compartmentalization.  Sugar maples are particularly good at making this barrier.  It does take a while and this allows for sap to be collected for a few weeks but eventually, the tree heals over the wound, both internally and externally and will prevent large scale infections from happening.  The staining associated with this response to the wound is much greater above and below the wound versus than side to side.  If you have ever cut into a piece of sugar maple wood that’s been tapped you have probably seen these long, narrow areas of staining.  That stained wood will not conduct sap anymore.  So sugar makers have to most new tap holes all around the stem in order to find clean wood.  After the sugaring season is over, the tree starts growing again and the tree actually grows new wood over the old wood and where the wounding took place.  Over time, a tree adds enough wood that you can tap directly above or below old tap holes but it may take 20 years for that to happen.  Good, healthy trees will grow more wood faster.  So it’s a good idea for maple producers to carefully tent for their trees and make sure tree health is a priority.

The First Sugarmakers

Who were the first sugar makers?   Many believe native Americans were the first to collect sugar from maple trees in North America.  In fact, it was probably squirrels.  Squirrels have been observed collecting encrusted sugar from the end twigs they nipped off and make a habit of going from tree to tree.  In fact, UVM researchers have quantified squirrels collecting as much as 80mg of sugar from each twig.  It’s very possible that native Americans observed this behavior and found a way to collect sugar much closer to the ground.  

Traditional Collection Methods

Traditional methods of sap collection have changed over time.  Initially, Native Americans created gashes in the stem, and directed sap into wooden or bark vessels.    Early spouts were created by hollowing out small twigs, which were inserted into tapholes created with a hammer and chisel.  Sap flowed into wooden buckets placed on the ground.  Later, a bit and brace were used to produce the taphole, and mass‐produced cast or rolled metal spouts were employed to both direct sap into wooden, then later metal buckets, and to hold the bucket above the ground.

Tubing

Although sap is still collected by some maple producers in buckets or plastic bags, the majority of maple sap is currently collected using plastic spouts and a network of tubing lines.  The standard tubing used for the lines that run from tree to tree is 5/16” (inside diameter).  Typically, 5‐20 taps are connected together using this tubing to form a lateral line, which, is then connected into larger diameter tubing called mainline.  These mainlines run downhill into storage tanks where sap accumulates for later processing into maple syrup.  Sometimes it’s good to think of a tubing system as a watershed; with the lateral lines being the small streams and the mainlines being increasingly larger rivers.  

USDA Numbers

The USDA released the estimates for the 2019 Vermont maple crop.  The numbers show that Vermont produced just over 2 million gallons of syrup in 2019.  This represents a nearly 50% of all the syrup produced in the US and just under 7% increase from 2018.  Almost all of this increase is explained by an increase in taps between the two years.  Vermont also lead the nation in terms of syrup yield per tap.  Vermont’s sugar makers on average gathered the equivalent of over a 1/3 of a gallon of syrup/tap in 2019.  The high yield per tap is explained by a combination of ideal weather during the sugaring season, use of vacuum and producer’s ability to find and repair leaks when they occur.  Reports of sweeter than average sap also help explain the strength of this year’s totals.  Sugar makers now turn to the business of marketing their hard earned crop. 

Vacuum

Sap flows out of trees due to the difference in pressure between the inside and outside of the tree.   In the 1950s, maple researchers and producers found that adding vacuum pumps to tubing   systems   could increase this pressure differential and thereby increase sap yields.  Use of modern equipment, materials, and techniques   for   tubing systems, combined with a proper vacuum pump can result in yields 2‐3 times higher than that from traditional bucket (gravity) sap collection.   The use of vacuum does not result in additional damage to the tree.

What's in the Sap?

Maple sap, what’s in it?  Maple sap is a dilute solution of mainly water (95‐99%) and sugar (1‐5%), along with trace amounts of other substances, including: organic acids, free amino acids, protein, minerals, and phenolic compounds.  Sap coming directly from the tree looks like water, and has only a slight sweet taste.  Most of the sugar in maple sap is sucrose (which chemically is the same as table sugar), with only very small amounts of other sugars present.  It is important to note that maple sap is not just dilute maple syrup.  It’s fundamentally a different product and only the heat of an evaporator can cause the color and flavor that makes maple syrup what it is.

Why Does Sap Flow?

Why Does Sap Flow from Maple Trees?  Throughout the maple region, there are several weeks of alternating freeze and thaw temperatures each spring. This weather provides the right conditions for sap flow in maple. Unlike most trees, maples have tiny air‐filled cells in their wood.  Freezing causes ice to form inside these cells. As this frost thickens, a suction is created which pulls water from the soil into the tree.  At the same time, the gas bubbles in the cells are compressed. When weather warms,  the  frost  melts  and  the  gas  bubbles  expand, causing pressure to form in the tree. This pressure pushes sap out of tap holes drilled by maple producers. In order for the sap to keep flowing, another freeze and thaw cycle must follow within in a day or two.

 

Syrup Quality

Adulteration

The law is very clear as to what can be sold as pure maple syrup; only the liquid derived by concentration and heat treatment of the sap of the maple tree.  No processing that adds or removes naturally occurring soluble materials is allowed.  This does not, however, include the use of approved filter-aids for the removal of suspended material such as sugar sand or niter or the use of approved defoamers.  Unfortunately, the relatively high price of pure maple syrup can provide the incentive for illegal adulteration with non-maple sugars and or artificial decolorizing agents.  This is quite rare and several analytical methods are available to detect the addition of other types of sugars in pure maple syrup.  Monitoring is conducted by both the maple industry and governmental organizations to detect any illegal products and remove them from the marketplace.  A case from 2011 brought to court by the US Food and Drug Administration when a sample of syrup was tested and determined to be 100% cane sugar proves that the laws can and will be enforced.

Color 1

Why is maple syrup different colors? Pure maple syrup ranges in color from light golden amber to dark reddish brown.  Over the course of the maple production season, the color of maple syrup produced in an individual maple operation will gradually progress from lighter to darker.    This progression is due primarily to the gradual changes in the composition of maple sap, warming of daytime temperatures during the production season and accompanying metabolic changes in the trees, and quantity of microbes over the course of the production season, all of which influence the balance of different sugars that develop color during evaporation.

Color 2

There are four grades of pure maple syrup, Golden Color/Delicate Taste, Amber Color/Rich Taste, Dark Color/Robust Taste and Very Dark Color/Strong Taste.  Each grade has a range in color, as defined by its light transmittance.  Knowing the color of pure maple syrup and into which grade it falls is one of the key elements to grading.  Vermont maple regulations state that Golden/Delicate syrup has a light transmittance not less than 75%, Amber between 74.9-50%, Dark between 49.9-25% and Very Dark less than 25%.  Using a temporary color comparator for color grading can be effective as long as the amber-colored glycerin samples haven’t faded with time or exposure to light.  Permanent glass comparators are available and will remain accurate over time but are more expensive.  Syrup will naturally darken over time. If syrup color is very close to the lower limit for a given grade when packed, it will likely be out of grade within a month or two.  Sugar makers are advised to keep this in mind when selling syrup in the retail market.

Containers

Plastic, Glass, or Tin: Which is Best?  Maple syrup is packed in a variety of retail containers.
• Glass – allows the color and clarity of maple syrup to clearly show.  A wide range of designs available. Best for maintaining flavor of syrup.
• Plastic – best for shipping.  Maintains the flavor of syrup, although color may darken somewhat in storage.
• Tin   –   traditional   packaging   appeals   to   many customers. Maintains color well.
Regardless of the packaging,  once  opened,  maple syrup should be refrigerated or frozen to maintain quality and flavor of the product.

Contest Entry

Summer is here and for many sugar makers that means maple contest time.  Entering syrup in a contest is a great way to show off your product, make sure your syrup meets grading standards and perhaps earn a class winner or best of show ribbon.  There are a few things to keep in mind before entering your product in a contest.  Perhaps the most important thing is to grade your own syrup right before entering.  Don’t rely on what how you graded the syrup during the season since syrup color will naturally darken over time.  Making sure your entry meets the standard for color, clarity, density, and flavor BEFORE entering is the best way to avoid having syrup rejected.  Also important is to use a clean, new container for your entry.  Many samples are rejected each year due to otherwise good syrup being entered in reused canning jars that retained the flavor from last year’s pickles or salsa.  When checking density make sure to account for syrup temperature.  Look at the sample to see if anything cloudy is present.  Syrup must be graded for color and will be rejected even if just slightly too dark for the grade.  Lastly, make sure to taste the sample and determine that the flavor is what you remember from the production season.  

Density

Producing pure maple syrup is a time honored tradition in Vermont.  Whether you are a large producer filling drums and selling on the bulk market or a backyard producer making just enough for family and a few lucky friends, syrup quality is critical.  There is too much time and effort involved to risk having the finished product spoil or otherwise become unusable.  Perhaps the most critical element of syrup production is boiling until the syrup is the correct density.  This process can be challenging if you are inexperienced or dealing with small volumes of syrup.  Correct density syrup is between 66.9 and 68.9 percent sugar.  Syrup that is low density will likely ferment or grow mold and syrup that is too dense will develop sugar crystals that are difficult to use.  It takes a long time to boil sap to syrup.  Sometimes the process can feel like it takes forever and that it will never reach syrup.  But as you approach syrup density the changes can be rapid.  This is the critical time to be paying attention.  A good quality thermometer and a maple syrup hydrometer are needed to correctly measure density.  For more information about how to correctly measure syrup density, search for University of Vermont Extension Maple.

Grading

Grade A pure maple syrup is graded on four criteria; density, clarity, color, and flavor.  All syrup must be fit within a standard density of 66.9-68.9 percent sugar.  Syrup must be clear and free of any suspended particles that could form during the boiling process.  Syrup is then placed in the correct color class based on established standards.  The four classes are; Golden, Amber, Dark and Very Dark.  Finally, flavor must be evaluated.  All syrup must be free of objectionable flavors or odors and generally have the correct flavor for the grade.  Lighter syrup being more delicate and the flavor becoming stronger as you go darker in color. 

Maple Color Grades

There are four grades of pure maple syrup; Golden Color/Delicate Taste, Amber Color/Rich Taste, Dark Color/Robust Taste and Very Dark Color/Strong Taste.  Each grade has a range in color as defined by its light transmittance.  Knowing the color of pure maple syrup and into which grade it falls is one of the key elements of grading.  Vermont maple regulations stipulate that Golden Color/Delicate Taste syrup has a light transmittance of not less than 75%, Amber between 74.9 and 50%, Dark between 49.9 and 25% and Very Dark, less than 25% light transmittance.  Using a temporary color comparator for grading can be effective as long as the amber-colored glycerin samples haven’t faded with time or exposure to light.  Permanent glass comparators are available and will remain accurate over time but are more expensive.  Syrup will naturally darken over time.  If the syrup color is very close to the lower limit for a given grade when packed, it will likely be out of grade within a month or two.  Sugar makers are advised to keep this in mind when selling syrup in the retail market.  

Maple Laws

The law is very clear on what can be sold as pure maple syrup; only “the liquid derived by concentration and heat treatment of the sap of the maple tree”.  No processing that “adds or removes naturally occurring soluble materials” is allowed.  This does not, however, include the use of approved filter aids for the removal of suspended material such as sugar sand or the use of approved defoamers.  Unfortunately, the relatively high price of pure maple syrup can provide an incentive for illegal adulteration with non-maple sugars and/or artificial decolorizing agents.  This is quite rare and several analytical methods are available to detect the addition of other types of sugars to maple syrup.  Monitoring is conducted by both the maple industry and governmental organizations to detect any illegal products and to remove them from the marketplace.  A case from 2011 brought to court by the US Food and Drug Administration when a sample of syrup tested and determined to be 100% cane sugar proves that the laws can and will be enforced.  

Regulations

Vermont laws governing the production and sale of pure maple syrup grant the authority to regulate to the Vermont Agency of Agriculture Food and Markets.  The regulations that have been developed as a result of those laws cover everything from the precise definition of pure maple syrup to what information must be included on the label and everything in between.  Sugar makers or processors that bottle others syrup must be familiar and follow these regulations or risk product being removed from sale and or fines.  Among these regulations is the stipulation that: “No maple syrup may be labeled as being a Vermont product, or labeled in any manner which would imply that the maple syrup was produced in Vermont unless the maple syrup is 100 percent pure maple syrup which was entirely produced within the state of Vermont”.  If a producer or processor is unsure if their label meets the requirements they may request a review by the Agency of Agriculture. 

Syrup Clarity

Syrup clarity is one of the four basics of grading.  Syrup that come right off the evaporator is cloudy.  Most of the cloudiness found in unfiltered syrup is naturally occurring minerals such as calcium also known as sugar sand or niter. Syrup clarity is a reflection of how well this cloudiness has been removed during filtering. Filtering through felt filters uses gravity, and while not as effective as pressure filtering, it can produce acceptable results. Most sugar makers with more than a hundred or so taps will use pressure filters to speed up the process.
• If using gravity filtering methods, remember that damaged cloth filters can allow unfiltered syrup to pass. Avoid twisting or wringing the fabric when rinsing.
• More sugar sand can be formed while canning. Avoid this by keeping filtered syrup between 180-200F when canning and not keeping syrup hot longer than necessary.  
• Sometimes sugar sand is too fine to be caught in either a cloth filter or filter press.  The result is syrup with a slight haze. Regulations require that packaged syrup is “practically clear”.  Although syrup filtered through cloth may not have the polish of pressure filtered syrup, if done correctly, it will be acceptable.  

Syrup Color

In Vermont, Grade A maple syrup is divided into four distinct color classes.  Those classes are Golden, Amber, Dark and Very Dark.  The lightest grade of syrup, Golden, has the most delicate flavor.  A lot of the time it will be made at the beginning of the season.  Air temperatures are cooler, sap is quite clear and you end up making a lighter color syrup.  As the season progresses and air temperatures become a little bit warmer you will start to make darker colored syrup.  The end of the season almost always ends with Very Dark colored syrup.  Each grade has to fit within the same range in density.  Sometimes it can appear that lighter colored syrup is less thick than dark syrup but it’s actually not true.  They are all the same density.  The flavor of the syrup is closely tied to its color.  Lighter syrup will be more delicate in flavor and the flavor will get stronger as you go darker in color.  So your personal preference will really determine which grade of syrup you like the best.  And if you are trying to cook with it, you will probably want a syrup with a stronger flavor because the flavor of the maple will come through better than some of the lighter grades of syrup where the flavor is a little more delicate and not as strong.  

Syrup Contest Entry

Summer is here and for maple sugar makers that means contest time.  Entering syrup in a contest is a great way to show off your product, make sure your syrup meets standards and earn a class winner or best is show ribbon.  There are a few things to keep in mind before entering a contest.  Perhaps the most important is to grade your syrup right before entering.  Don’t rely on how you graded the syrup during the season since syrup color will naturally darken over time.  Making sure your entry meets the standard for color, clarity, density, and flavor before entering is the best way to avoid having syrup rejected.  Also important is to use a clean, new container for your entry.  Many samples are rejected each year due to otherwise good syrup being entered in reused canning jars that retain the flavor from last year’s pickles or salsa.  When checking syrup density, make sure to account for syrup temperature.  Look at the sample and see if anything cloudy is present.  Syrup must be graded for color and will be rejected even if it is just slightly too dark for the grade.  Lastly, and perhaps most importantly, make sure to taste the sample and determine that the flavor is what you remember it from the production season.

Contact

Mark.Isselhardt@uvm.edu | 802-899-9926

Extension maple specialist Mark Isselhardt performs original research related to the production of maple syrup. His focus is on issues that are relevant to all producers regardless of the size of operation. Mark works with Vermont's maple producers, sharing research and information to help them ensure long-term tree health, improve management of their sugarbush and increase profitability through higher sap yield, syrup production efficiency and sales. In addition to conducting research and consulting with producers, he is involved in organizing educational meetings including the annual January Maple Conferences.