U.S. DEPARTMENT OF AGRICULTURE CONTENTS Page Page CLARIFICATION OF SIRUP 29 3 ECONOMICS Sugar sand 29 SUGAR MAPLES 3 Sedimentation 29 THE SUGAR GROVE 4 Filtration 29 5 Sap yields Flat filters 30 5 Summary Summary 30 STANDARDS FOR MAPLE SIRUP 31 5 TAPPING THE TREE For retail sale 31 5 Date of tapping United States standards for table maple sirup.. 31 6 Selection of trees Su mmary 32 6 Boring the taphole CHECKING AND ADJUSTING THE DENSITY 6 Life of a taphole OF SIRUP 32 7 Summary Weight method 32 7 SPOUTS AND BUCKETS Refractometry method 32 7 Sap spouts Hydrometry method 32 7 Rainguards The Brix scale 33 7 Sap buckets The Baume scale 33 8 Summary Making the density measurement 33 8 GATHERING THE SAP Correcting for temperature 34 8 Collecting tanks Adjusting the density of the sirup 36 8 Pipelines Alligation (Pearson's square) 36 9 Storage tanks Summary 36 9 Summary GRADING THE SIRUP BY COLOR 37 9 THE EVAPORATOR HOUSE Color standards 37 9 Location of building U.S. color comparator 37 9 Function of the evaporator house Use of the color comparator 37 9 Requirements of the evaporator house Summary 38 10 Design of the evaporator house PACKAGING 38 10 Steam ventilation Stack burn 38 1 Location of the evaporator Control of micro-organisms 38 1 Air supply Size and type of package 38 1 Sirup processing room Summary 39 1 Wood storage MAPLE SUGAR 39 1 Storage tanks The equipment 39 12 Summary The chemistry of maple sugar 39 Formation of crystal sugar 40 12 THE EVAPORATOR AND ITS FUNCTION Invert sugar 40 12 Design Doctor 40 13 Rule of 86 Summary 40 13 Changes in sap during its evaporation to sirup. MAPLE CREAM OR BUTTER 41 15 The evaporation time Sirup for creaming 41 16 Liquid level in the evaporator Invert-sugar content 41 16 Rates of evaporation Cooking and cooling 41 16 Summary Creaming 42 17 OPERATING THE EVAPORATOR Holding cream for delayed packaging 42 17 Starting the evaporator Packaging and storing maple cream 42 17 Drawing off the sirup Summary 42 Automatic drawofif valve 18 SOFT-SUGAR CANDIES 42 Finishing pan 18 Cooking, cooling, and stirring 43 Completion of run of sap 18 The bob 43 Cleaning the evaporator _' 18 Crystal coating of candies 43 19 Summary Packaging candies 44 OTHER TYPES OF EVAPORATORS 19 Summary 44 Steam evaporator 19 MAPLE SPREAD 44 19 Vacuum evaporator Summary 45 High-speed tube-type evaporator 20 HIGH-FLAVORED MAPLE SIRUP 45 Summary 20 Atmospheric process 45 FUEL 20 Pressure-cooking process 46 20 Wood Uses of high-flavored sirup 46 Oil 21 Summary 47 Summary 21 CRYSTALLINE HONEY-MAPLE SPREAD 47 MAPLE SIRUP 22 Summary 47 Composition of sap and sirup 22 OTHER MAPLE CONFECTIONS 47 Color and flavor 23 Rock candy 47 Factors controlling color and flavor 24 Hard sugar 48 Rules of sirupmaking 24 Granulated or stirred sugar 48 Grades of sirup 24 Maple on snow 48 Summary 25 Summary 48 CONTROL OF FINISHED SIRUP TESTING MAPLE SIRUP FOR INVERT SUGAR. 48 25 Viscosity of maple sirup Preparing the sirup-and-water dilutions 49 25 Old standards of finished sirup 25 Testing for color 49 Use of precision instruments Interpreting the color test 50 26 Elevation of the boiling point 26 The simplified test 50 Special thermometers 27 Summary 50 LITERATURE CITED 50 Hydrometers 28 SUPPLEMENTAL READING 52 Summary 29 MAPLE-SIRUP PRODUCERS MANUAL By C. O. Willits, Eastern Utilization Research and Development Division, Agricultural Research Service No one knows who first discovered how to make Annual production of maple sirup, like other sirup and sugar from the sap of the maple tree. crops, is subject to yearly fluctuations caused by Both products were well established items of bar- climatic and economic conditions. Production in ter among the Indians living in the area of the the past has been affected by the cost or supply of Great Lakes and the St. Lawrence River, even white sugar and by the supply of farm labor. In before the arrival of the white man (ü, S7) .^ ^ 1860, a record crop of 4,132,000 gallons of maple The maple crop has three claims to distinction : sirup was produced. For the next decade the pribe (1) It is one of our oldest agricultural commodi- of cane sugar declined and so did production of ties; (2) it is one of the few crops whose produc- maple sirup, reaching a low of 921,000 gallons in tion is solely American; and (3) it is the only 1869. As cane sugar became scarce during World crop that must be processed on the farm before it War I, production of maple sirup again rose, is in suitable form for sale. slightly exceeding the 1860 record. An increase Although maple-sirup production is recognized occurred also during World War II. Since then, as one of our oldest industries, relatively little there has been a decrease in production (table 1) scientific work has been done to improve it. The (4^,4?'). sap has been collected and converted to sirup in much the same way since the development of at- mospheric evaporation equipment about 1900. This equipment was developed by Yankee inge- nuity, not engineering studies. Today, a strong research program dealing with the different phases of maple-sirup production is being con- ducted by the Eastern Utilization Research and Development Division of the united States De- partment of Agriculture and by the experiment stations and agricultural colleges of Michigan, New Hampshire, New York, Ohio, and Vermont. As a result of this research a noticeable change is occurring in the maple-sirup industry, and this will be described throughout this handbook. Maple sirup is a woodland crop. The trees grow ibest at altitudes of 600 feet and above ; there- fore, maple sirup is usually produced in the hilly country. Its production is a vital part of the local economy in dozens of communities from Maine westward into Minnesota, and south to Indiana and West Virginia (chart 1). The same type and quality of maple products are produced through- out the area. ^ Also communication from J. A. Mason, the University Museum, University of Pennsylvania. ^ Italic numbers in parentheses refer to Literature Chart 1.—A, Range of commercial production of maple sirup; Cited, p. 50. B, range of hard maple trees. TABLE 1.—Production of maple sugar and sirup^ trees tapped^ average price received hy farmers^ and imports^ selected years^ 1918-5Jt. Production Price Imports for consumption Year Trees Total Average total pro- Per Per tapped product duction per tree pound gallon Sugar Sirup in terms of of Sugar 2 Sirup ^ of sugar 1 sugar sirup As sugar ^ As sirup 1 Thousand Thousand Thousand Thousand Thousand Thousand trees pounds gallons pounds Pounds Gallons Cents Dollars pounds pounds 1918 17, 053 11,383 4,141 44, 511 2.61 0.33 3,807 1922 15, 198 5,227 3,370 32, 187 2. 12 .26 _ _ 3,201 * 1 1926 13, 948 3,585 3,504 31,617 2. 27 .28 29.3 2. 12 3,446 203 1930 _ _ 13, 158 2, 134 3,712 31, 830 2.42 .30 30.2 2.03 9,735 1,575 1934 12, 099 1,044 2,444 20, 596 1.70 .21 24.9 1.33 2,976 1,316 1938 11,380 705 2,770 22, 865 2.01 .25 28. 4 1.61 3,946 39 1942 10, 046 560 2,987 24, 456 2.43 .30 37.7 2.26 7, 121 4,791 1946 8,257 310 1,351 11, 118 1.35 . 17 65.5 3.30 4,207 2,221 1950 8, 146 257 2,024 16, 449 2.02 .25 77.8 4. 13 6,549 5,282 19545 6,786 168 1,730 14, 014 2.07 .26 85. 1 4.66 6,643 4,096 1 Assuming that 1 gallon of sirup is equivalent to 8 pounds of sugar. 2 Includes maple sirup through Sept. 21, 1922. 3 A gallon of sirup weighs about 11 pounds. ^ Included with maple sugar through Sept. 21, 1922. 5 Preliminary. Agricultural Statistics, 1952 and 1955 (46y 47). The decreased production since World War II TABLE 2.—Number of tappable maple trees^ and is not necessarily a trend. Rather it is a reflection number and percentage tapped^ Eastern States^ of the shortage of farm labor during this period. 1951 Although the downward trend tends to exist in the country as a whole, production of maple sirup in Minnesota, Wisconsin, and Michigan has shown State Tappable Tapped trees trees ^ a definite increase. In fact, based on the number of tappable trees, production in these States could exceed production in New York and the North- Number Number Percent Maine _ 53, 553, 000 136, 000 0.25 eastern States. For example, Michigan has one- Maryland _ _ 1, 660, 000 28, 000 1.7 fifth of the total stand of maple trees. Massachusetts 11,913,000 166, 000 1.4 Current surveys in the eastern maple-produc- New Hampshire 12, 103, 000 261, 000 2.2 ing areas (47) ^ of the number of maple trees that New York_ 73, 128, 000 1,960,000 2.7 Pennsylvania _ 33,553,000 422, 000 1.3 are tapped as well as the total number that are of Vermont- _ - - 25, 840, 000 3, 118,000 12. 1 West Virginia 13, 031, 000 ®Also unpublished estimates for 1948-52 of the North- eastern Forest Experiment Station (Ü. S. Forest Service), Upper Darby, Pa. 1 Larger than 10 inches d. b. h. TABLE I >.—Rank• of States in production o / maple sugar^ selected years^ 1916-5Jf. Rank 1916 1921 1926 1931 1936 1941 1946 1951 1953 1954 1 N. Y. Vt. N. Y. Vt. Vt. Vt. Vt.. Vt. Vt. Vt. 2 Vt. N. Y. Vt. N. Y. N. Y. N. Y. N. Y. N. Y. N. Y. N. Y. 3 __ _ _ Ohio Ohio Ohio Ohio Ohio Ohio Ohio Pa. Ohio Pa. 4___ Pa. Mich. Pa. Pa. Pa. Pa. Mich. Mich. Pa. Mich. 5 N. H. N. H. Mich. Mich. Mich. Mich. Pa. Mass. Wis. Ohio 6 Mich. Pa. N. H. Wis. Wis. Mass. N. H. N. H. Mich. N. H. 7 _____ Wis. Wis. Mass. N. H. N. H. N. H. Mass. Wis. N. H. Wis. 8--_ Mass. Mass. Wis. Mass. Mass. Wis. Wis. Maine Mass. Mass. 9__ Maine Maine Maine Md. Md. Maine Maine Md. Minn. Maine 10 - - _ Md. Md. Md. Maine Maine Md. Md. Ohio Md. Md. 11 Minn. Maine Minn. tappable size show that the industry is not suffer- The chief functions of these associations are to ing from too few trees. Although many sugar maintain adequate supplies, to promote sales, and maples have been cut for lumber, vast stands still to maintain the quality of the products. A num- exist and these can supply our maple-sirup needs. ber of communities hold annual festivals to stim- Table 2 shows the number of maple trees of tap- ulate interest in maple products. pable size and the percentage that were tapped in Also, the different States, in cooperation with the Agricultural Eesearch Service and the Ex- 1951. Table 3 shows the production of maple sirup by tension Service of the United States Department the 11 principal States for selected years, 1916-54. of Agriculture, have set up a strong extension program. This program has done much to bring the results of research directly to maple pro- ducers. In New York, which has taken a lead in this adult education program, it is not un- common for more than a thousand producers to attend the "maple sirup" schools held annually throughout the State in the premaple season. ECONOMICS The maple season is short and comes in the early spring when most other farm activities are slowest, so it does not compete with them. Maple sirup can be considered a byproduct of the farm. SUGAR MAPLES However, surveys in New York {2, Ji)^ Ohio {18)^ Michigan (^^), and Wisconsin (^) have shown that production of maple sirup is one of the farm- er's most profitable enterprises, paying him as Only 2 of the 13 species of maples {Acer) native much as $3 per hour for every hour spent, in- to the United States are of importance in the pro- cluding time spent in cleaning the equipment and duction of sirup because of the sweetness (sugar collecting and boiling the sap. content) of their sap {3^ 13^ 46). Modernization of equipment has done much to Acer saccharum Marsh, (better known as increase profits in maple-sirup production. This sugar maple, hard maple, rock maple, or sugar includes the use of flue-type evaporators, oil as tree) furnishes three-fourths of all sap used in fuel, mechanical tapping tools, and instruments the production of maple sirup. Although this for judging finished sirup. All these tend to re- tree grows throughout the maple-producing areas duce labor costs and contribute to the production (Chart 1, A and B) the largest numbers are in of better grades of sirup that have a correspond- the Lake States and the Northeast. The tree ingly greater value. Fixed costs, which normally grows singly and in groups in mixed stands of represent about 35 percent of the total, may lower hardwoods. The trunk of a mature tree may be net income in groves where fewer than 500 buck- 30 to 40 inches in diameter. It is a prolific seeder ets are hung. and endures shade well, but unfortunately it does The sirup can be sold immediately and so pro- not grow rapidly. The tree is best distinguished duce a ready source of cash, or it can be held for by its leaf (chart 2). a more favorable market or to supply raw mate- Acer nigrum Michx. F. (black sugar maple, rial for production of other more profitable maple hard maple, or sugar maple) grows over a smaller products. If the sirup is held, it can be used as range than J.. saccharum. It does not grow as far collateral for short-term loans. north or south, but it is more abundant in the Since 1940 the proportion of the maple sirup western part of its range. This tree is similar to produced in the United States that has been sold A, saccharum in both sap production and ap- directly to the consumer by the producer has in- pearance. Its principal distinguishing feature is creased. This in many instances has resulted in the large drooping leaf of midsummer (chart 2). increased returns for him. To stabilize this ex- Other species of maples commonly found in our panded outlet, the producer has improved the hardwood forests are the red maple {Acer rubrwn appearance of the package and the quality of the L.) and the silver maple {A, saccharinum L.). sirup so that it meets State and Federal specifi- These trees, readily identified by their leaves cations. Many producers are converting their (chart 2), are not good sources of maple sirup sirup to confections such as "maple cream," pra- because their sap is less sweet and often contains lines, and soft-sugar candies, which result in even excessive amounts of sugar sand. The red maple, larger returns. Maple-sirup producers have the more common of the two, is easily identified formed associations so they can pool their stocks. in the spring by the red color of its buds. BLACK MAPLE SUGAR MAPLE RED MAPLE SILVER MAPLE Chart 2.—Leaves of the sugar maple (Acer saccfiorum Marsh.), red mapie U. rubrum U, silver maple iA. saccharînum U, and black maple {A, nigrum Michx. F.). but the cost of labor for collecting sap increases. Figures 1 and 2 show a maple grove (bush) with the large full crowns that are so important to the production of large amounts of sweet sap. THE SUGAR GROVE For maximum returns, the grove should con- tain at least 500 trees of tappable size, that is, 10 inches in diameter at breast height (d. b. h.). Groves with fewer than 10 maple trees per acre Most maple-sugar groves, often called sugar are not profitable; 25 to 30 trees to the acre bushes, are parts of stands of old hardwood for- is ideal (19). ests. In the ideal sugar grove most of the other Maples grown in the open, for example, along trees have been cut out and the maples have the roadside (fig. 3), have large crowns and are been thinned sufficiently to allow the trees to de- excellent sap producers (20). Because of their velop a good crown growth. This should be done shorter boles, roadside trees do not make as good according to a carefully planned program, with saw logs as trees that grow under crowded con- the assistance of the State extension forester and ditions. However, trees in a crowded stand have the State forester for the area. If the stand is smaller crowns and consequently they are not made up entirely of maples, approximately the good sap producers (figs. 4 and 5). same volume of sap is produced per acre re- The ideal sugar grove requires not only a fardless of the size of the trees (21). As the num- planned spacing of the trees but also a good un- er of trees per acre increases, the size of the derstory to protect the ground, keep it moist, crowns and boles and the yield per tree decreases. and permit the growth of seedling maples to re- place trees that have matured and can be cut for Trees producing sap with a sugar content of 10 lumber (figs. 6 and 7). percent would be especially profitable, as 15 gal- lons from 1 taphole will yield nearly 1% gallons Sap Yields of sirup. The yield of sap in a sugar bush should be Eesearch is being conducted at the Universities expressed in terms of the number of tapholes of Vermont and New Hampshire on the propaga- rather than the number of trees. The yield per tion of maple trees from selected high-yielding hole is independent of the number of holes per trees (7). This research should eventually make tree and ranges from 5 to 15 gallons. It is not possible the setting out of maple orchards or uncommon for a taphole to produce from 40 to 80 roadside trees that will produce sap with a high gallons of sap and as much as 3 quarts of sirup sugar content. in a single year. The sugar content of the sap Summary produced by the different trees in a grove varies considerably. The sap produced by the average ] 1. Consult your State extension forester, farm tree has a sugar content of 2° to 3"^ Brix.^ Fre- / forester, and county agricultural agent and quently trees produce sap with a sugar content ' work with them to develop a management plan of less than 1° Brix, and occasionally a tree for your sugar grove. This plan should include produces sap with as much as 9° or even 11° removing defective, diseased, and weed trees to Brix. obtain maximum growth and sap production The yield and sweetness of the sap produced from crop trees. by a tree varies from year to year, but trees that produce sap with a high sugar content and trees that produce sap with a low sugar content main- tain their relative positions from year to year. It is important to know the exact sugar content of the sap produced by each tree. Those trees that produce sap low in sugar (1 percent or less) should be culled. It is not difficult to measure TAPPING THE TREE the sugar content of sap. All that is needed is a sap hydrometer and a thermometer. These can be bought from any maple-sirup equipment The sap of the sugar maple, from which sirup house. and sugar are made, appears to be different from To make the reading, float the hydrometer in the circulatory sap of a growing tree. We know the sap bucket (fig. 8) or in a hydrometer can containing the sap (fig. 9). There should be no little concerning this sap, or sweet water as it is ice in the sap. The temperature of the sap must called in western Pennsylvania. Intensive study also be obtained so the hydrometer reading can of maple sap, being conducted at the University be corrected. Subtract 0.4° Brix for tempera- of Vermont, should lead to a better understanding tures of 32° to 50° F., 0.3° Brix for temperatures of its nature, function, and source (Í4? J¿) • of 51° to 59° F., and 0.1° Brix for temperatures Maple trees will produce flows of sap any time of 60° to 68° F. from late fall after they have lost their leaves until The hydrometer is usually calibrated from 0° well into the spring, each time a period of freezing to 10° Brix, with divisions of 0.5°. A more ac- is followed by a period of thawing. The sap will curate measurement can be obtained by using a now from a wound in the sapwood, whether the hydrometer with divisions of 0.1° (fig. 9), with wound is from a hole bored in the tree or from a a refractometer, or by a quantitative chemical broken twig. analysis. A taphole that produces 15 gallons of sap with Date of Tapping a sugar content of 2° Brix will yield 2.5 pounds To establish a rule of thumb that can be used of sugar or one-third of a gallon of sirup, where- to set the date when sugar maples should be tapped as a taphole that produces 15 gallons of sap with is not a simple matter. The date should be early a sugar content of 1° Brix will yield only 1.3 enough to assure the collection of large early flows pounds of sugar, or less than one-fifth of a gallon of sap but not so early that only a small flow oc- of sirup. The cost of producing the sirup from curs followed by a long period of no flow. Michi- both tapholes will be approximately the same. gan and New York provide sugarmakers with radio weather forecasts of the correct tapping ^ The density of sap and sirup is due to a mixture of dissolved solids and not just sugar. The physical in- dates {9)j and a similar service is being set up in struments used to measure the density of sap and sirup other maple-producing States including Massa- do not distinguish between the density due to sugar chusetts, Wisconsin, and Vermont. Generally, and that due to other solids. The degrees Brix (° Brix) trees should not be tapped according to a calendar means that the solution has the same density as a solu- tion containing a percentage of sugar numerically equal date. For example, in 1953 when this practice was to the Brix value. followed, many producers failed to collect the early and largest flow of sap. In many instances For large operations, where the additional ex- a third of the crop was lost. pense justifies its cost, a portable motor-driven The best plan is to watch the weather maps, be- drill (fig. 14) not only speeds up the operation ginning about the first or middle of February. but is far less fatiguing. When the map shows a warm front moving across With a motorized tapping outfit one man can the country from West to East, which will cause drill holes as rapidly as a crew of three can set the temperature to climb from below freezing at the spouts and hang the buckets or bags. The de- velopment of this tool is one of the outstanding night to 40° or 50° F. in the daytime for a period mechanizations that have occurred in the indus- of 2 or 3 days, the trees in a particular area should be tapped before the warm front reaches that area. The hole is bored straight into the tree (prefer- In 1954, favorable weather occurred in most sec- ably perpendicular to the tree) to a depth of 3 tions of the country about February 18,19, and 20, inches or until stained wood is reached. Studies whereas records show that the normal tapping date at Michigan State university have shown that a for most areas is after the middle of March. To taphole 3 inches deep (fig. 15) will produce up take full advantage of these early flow periods the to 25 percent more sap than a taphole only 2 inches sirup maker must be prepared. The trees must deep. be selected, all of the equipment must be clean, The position of the first taphole is selected sterile, and in order, and the evaporator house arbitrarily. The hole should be 2 or 3 feet above must be ready to put into operation on 1 or 2 days' the ground, or if there is snow on the ground, as notice. close as possible to this height. This low posi- tion is particularly well suited to the use of the Selection of Trees plastic bag. The compass location of the hole The selection of the trees for tapping is of is not important. Data obtained in New York greatest importance and can be done at any time {4^3) and in Michigan ® have shown that the total throughout the year. Culling low-yielding trees yield per season is essentially the same regard- must be done during the period of sap flow {19), less of the compass location of the hole. Data Trees selected for tapping should measure 10 also show that the distance above ground level inches or more in diameter 4i/^ feet above the has little effect on yield. The best practice is to ground (10 inches d. b. h.) (fig. 10). make the new hole on successive years 6 to 8 A good rule (^, 19) for determining the number inches from the previous year's taphole, work- of tapholes that can safely be made in a single ing up the tree in a spiral pattern until the hole tree is as follows : is at breast height (fig. 16). With this proce- dure, the producer may tap his tree year after Tapholes Diameter of tree, per tree^ year in different quadrants and avoid striking inches niimher an old taphole or dead tissue that has been hidden Less than 10 0 10 to 14 1 by new bark, either of which would result in a 15 to 19 2 smaller flow and poorer quality sap. 20 to 24 3 The time required for new bark to grow over 25 or more 4 a taphole depends on the health and vigor of the * Number of buckets. tree. It is not uncommon to find the hole nearly covered in a year, as shown in figure 17. The To undertap a tree reduces the potential size hole itself remains open, but fungus growth {S9) of the crop without any benefit to the tree. On the that may occur in the new hole stains the wood other hand, to overtap (fig. 11) may result in several inches above and below the hole and an serious damage to the tree. The extent of such inch or less to the sides, as shown in figure 18 damage is the subject of a study being conducted (cross section of a maple log) and in figure 19 at Michigan State University. (longitudinal split of a log). Once the trees have been measured, it is well to mark them so they will not have to be remeasured Life of a Taphole each succeeding season. This can be done by paint- ing a numeral or a series of dots on the tree or by A taphole should be usable from the time it is using paints of different colors, such as white for bored until the buds begin to swell and the sirup 1 taphole, yellow for 2 tapholes, etc. acquires an unpalatable or buddy flavor. In practice, this is seldom the case. Instead, the Boring the Taphole taphole usually "dries up" within 3 or 4 weeks after the hole is bored. This drying up is caused The taphole is made by boring with either a by growth of micro-organisms in the taphole %-inch or %6-inch fast-cutting wood bit. This rather than by air-drying of the wood tissue. can be done either by hand, with a carpenter's brace or breast drill, or with a motorized tool. The brace (fig. 12) is slower than the breast drill 5 BOBBINS, P. W. POSITION OF TAPPING AND OTHER FAC- TORS AFFECTING THE FLOW OF MAPLE SAP. 1948. [Unpub- but less fatiguing. Some prefer the faster acting Ushed master's thesis. Copy on file in Library, Mich. machinist's drill (fig. 13). State Univ., East Lansing.] When the microbial growth has reached a count inserted in adjacent tapholes carried the sap to of 1 million per cubic centimeter, sap will no the same container (fig. 20). >. longer flow from the hole, and it is said to be There are only a few basic differences in the dried up i(2If). design of the various sap spouts or spiles. Some V In the past, a dried-up taphole was reamed to have a large opening at the delivery end. Others cause it to flow again, for it was assumed that have a hook to support the bucket and a hole for ^ ^ this procedure would remove the air-dried wood attaching the bucket cover. On others the bucket tissue. Reaming was never successful and this is supported directly on the spout. A few spouts can be readily explained. Research has shown are shown in figure 21. All spouts have a tapered .^ that the reaming bit did not sterilize the hole. shoulder so that when they are driven into posi- Only a layer of the microbial deposit was re- tion in the taphole, they form a watertight seal >. moved, with the result that the remaining bac- with the bark and outer sapwood but leave a free teria kept on growing and soon sufficient numbers space between the sapwood and the spout (fig. ^ ^ were again produced to stop sap flow. Investi- 15). In setting the spout (fig. 22) care must be gations being conducted at Michigan State Uni- exercised not to split the tree at the top and bot- versity on the problem of taphole infection may tom of the taphole. Such a split results in leak- lead to ways by which the taphole can be main- age of the sap and often causes complete loss of tained in a sterile condition throughout the sap sap from that hole. ^ season. Until such information is available the best practice is to keep the sap-collecting equip- Rainguards •- y ment sterile and clean. Heavy rains often occur during the sap season. '^ Summary Rainwater picks up dirt and leaches tannins from the bark. Both the dirt and the tannins, if per- ^ 1. Don't tap by the calendar. Follow your State's mitted to get into the sap bucket, will lower the ^ maple weather reports. grade of the sirup produced. Most sap spouts are 2. Make 1 taphole in a tree 10 inches in diameter, provided with "drip tips" to deflect runoff rain- -m and 1 additional hole for each additional 5 water from the tree and prevent it from entering inches of the tree's diameter. the bucket. In heavy downpours, drip tips are 8. Make the taphole with a %-inch or %ß-inch often inadequate. Use of a simple, homemade fast-cutting (special) wood bit. rubber rainguard (fig. 23) will make it impossible ^ 4. Bore the hole straight into the tree to a depth for the heaviest runoff rainwater to enter either of 3 inches. a sap bucket or bag. ^ 5. The location of the taphole in respect to com- To make a rainguard, cut a 2-inch square from y pass position and roots is unimportant. a thin sheet of rubber, such as an old inner tube. 6. Space the holes at least 6 inches apart (circum- Cut a %6-inch hole in the center of the square with < ference of tree) and in a spiral pattern. a leather punch. Slip the rainguard over the end 7. Use a power tapper if the grove is large of the spout near the tree and set it far enough enough to justify the expense. forward so that when the spout is seated in the taphole there will be a free space of i/4 to % inch between the rubber guard and the bark of the tree. Sap Buckets Three different types of containers have been used to collect the sap from the spout: (1) The SPOUTS AND BUCKETS wooden bucket, (2) the metal bucket, and (3) the plastic bag. The wooden bucket, because of its size and the care required to keep it watertight, has largely disappeared from use. Zinc-coated ^ Sap Spouts metal buckets of 15-quart capacity are the most commonly used. Lead-coated metal (terneplate) The spout or spile has three important func- or lead-soldered buckets or buckets painted with a tions : (1) It conveys the sap from the taphole to lead paint should not be used because the lead may r a container; (2) it serves as a support on which be dissolved by the sap, and the sirup may contain to hang the sap bucket or bag; (3) it keeps ad- illegal amounts of lead. Aluminum buckets, use ventitious (wild or stray) bacteria from gaining of which is being subsidized in Canada, tend to access to the moist taphole, which should reduce eliminate most of the objections to metal buckets. ^ infection. All buckets should be provided with a cover to Over the years a large number of sap spouts keep out rain and falling debris. Covers are of have been designed and used, with special features two general types: (1) Those that are attached to ^. claimed for each. The earliest spouts were hollow the spout (fig. 24), and (2) those that are clamped reeds, often a foot or more in length. Two reeds to the bucket (fig. 25). The plastic sap bag (fig. 26), a recent develop- from one hole (for example, with the stripe away ment, is too new to be fully evaluated. Some of from the tree and plainly visible) ; then after its advantages and disadvantages are as follows : they are emptied, they are hung from the op- Advantages: (1) Because of their small bulk, posite hole. This makes it easy for the sap col- they require minimum storage space, and they are lector to tell whether or not a bucket has been easily transported to the woods and hung. (2) emptied and keeps him from skipping full The bags have an adequate self-co ver. (3) buckets as well as revisiting emptied buckets. Emptying the sap is a one-handed operation (fig. The only objection to this scheme is that a bucket 27). The bags need not be removed from the with holes on both sides holds less sap than a spout; they can be rotated on the spout. (4) Be- bucket with one hole because it hangs from the cause the plastic bags are transparent to sunlight spout at an angle. radiation, which is lethal to micro-organisms (fig. 28), they tend to keep the sap sterile {23), Collecting Tanks Sterile sap contributes to the production of high- quality sirup. Collecting tanks vary in size with the needs Disadvantages: (1) The bags have not been in of a particular sugar bush. The tanks usually use long enough to establish their life expectancy. are provided with a strainer, baffled to prevent (2) The capacity of the bag may be inadequate loss of sap by splashing, and a drainpipe. for a day's run. (3) The bags are subject to dam- The method of hauling the tank is governed age by rodents. (4) Washing and rinsing the by conditions in.the sugar bush. The tank can bags may be a problem. be mounted on any of several types of carrier, including stoneboat or skids, 2-wheel trailer, Summary high-wheeled wagon gear, and underslung rubber- tired 2-wheel trailer (figs. 30-34, inch). 1. Any of the commercially available spouts are High mounting of the tank (figs. 31, 32, and satisfactory. 33) should be avoided, because of the labor re- 2. Use only clean, sterile spouts. quired to lift the sap. usually an additional 3. Drive the spout into the taphole with a firm worker is needed. The lowest mounting, such as enough blow to seat it securely, but do not drive on a stoneboat or skids (fig. 30), requires the it so far as to cause a split in the bark and wood. least labor. A rig of excellent design is one with 4. Use a 2- X 2-inch rubber runoff rainguard on a low-mounted sump tank (fig. 35) provided with the spout. a self-contained power-driven pump to lift the 5. Do not use buckets coated with lead paint or sap up to the large tank (fig. 36). with terneplate. 6. Use a bucket that will hold a normal day's run Pipelines of sap. 7. Use only covered sap buckets or bags. To eliminate the costly labor of collecting sap by hand and to avoid the bad roads of the sugar bush, some producers have installed pipeline sys- tems. In these systems the sap is piped directly from the tapholes to a storage tank. The first pipeline systems did not become popular because of the excessive cost of installing the intricate piping system and also because poor-quality sirup GATHERING THE SAP resulted if the sap fermented in the pipeline. One factor that has made pipelines practical is the development of plastic tubes. These can Gathering the sap (fig. 29) is the most ex- be laid directly on the ground because sap pensive and laborious of all maple-sirupmaking trapped in a low spot or sap in the line will not operations. Sap collection is handwork and ac- burst the tube on freezing (fig. 37). The phe- counts for one-third or more of the cost of sirup nomenal growth in the use of pipeline systems production. since the development of today's lightweight Much time can be saved if the trees on both plastic tubing can be attributed to: (1) The in- sides of a roadway that are to be serviced from itial cost of plastic tubing is comparable to the that roadway bear a distinguishing mark and cost of buckets or plastic bags, (2) the cost of the trees to be serviced from an adjacent road- collecting the sap and transporting it from the way bear another mark. This prevents visiting tree to the storage tank is reduced, (3) seasonal the same tree from both roadways. Different (daily) labor requirements are reduced, and (4) colored paints can be used to mark the trees. no sap is lost by spillage or by dumping small Another timesaver requires punching a second intermittent runs. hole in the sap bucket opposite the first hole, Because of the short time plastic pipeline sys- and painting a stripe from the hole to the bot- tems have been in operation, no data are available tom of the bucket. The buckets are hung first to show : (1) The life expectancy of the tubing as 8