Management Options for Small-Scale Sugar Bush Operations
Part III - Sugar Bush Safety and Liability By Mark Richardson

This is the third article in a four-part series on how to manage the small-scale sugar bush. Part I focused on traditional management activities like planning, thinning and crop tree selection. Part II introduced various aspects of sugar bush health and how it influences long-term sustainability. Part III focuses on some activities associated “working” a sugar bush each spring: collecting sap, tapping practices and processing sap into maple products. Sugar bush health and safety and liability issues are also introduced. Part VI will discuss some general facts about maple that may be of interest to all landowners: Why does sap flow from maple trees and not others? How is syrup graded? What makes syrup tastes so good? Why do maple trees dominate this part of North America?

Introduction

If you ask just about any Canadian where maple syrup comes from, they will probably answer: maple syrup is made by boiling sap. Even though they may be living far outside the maple region or they might never buy or consume maple syrup most people know that pure maple syrup is made by removing water from maple sap. Although this may sound like a pretty simple process, making a product that is high in quality, safe to consume and sell, and economical to produce, takes know-how and in some cases, doesn’t come cheaply.

Maple sap, when it leaves the tree, is predominantly water with only a minor component of solids (usually in the two to three percent range). Although these solids are mostly made up of sugars, there are a number other compounds including amino acids, organic acids, phenolic compounds, hormones, minerals and salts, which factor into the biological process of breaking dormancy each spring after a long cold winter. It is these compounds which give maple syrup its characteristic maple flavour and it is these compounds combined with processing techniques that ultimately shape the final quality of the product.

The techniques you employ while operating your small-scale sugar bush each spring will have a direct effect on such things as product quality and quantity, sugar bush health and financial returns on investment of time and money. Although the process of making maple syrup may be relatively simple, the techniques and skill needed are not. Experience is the best teacher, and although it would not be possible in one article to describe all the best management practices associated with operating a sugar bush, there are a number of important areas to consider.

The rest of this article is dedicated to introducing some (but not all) of the best management practices (BMPs) associated with tapping trees, collecting sap, processing sap into syrup and producing a high-quality product that is safe to consume.

Tapping Maple Trees

How many taps per tree – the number of taps per tree should be governed by two main factors: the diameter of the tree at breast height (DBH) or 1.3 meters from the ground, and a tree’s health or vigour. Tapping a tree can be thought of as the controlled wounding of that tree, and even though a tap hole is not nearly as difficult to recover from as crown breakage or stem damage (especially at the base of the tree) inappropriate tapping practices can be responsible for tree decline and reduced sap flow. In short this really means don’t over-tap your maples.

There are two possible scenarios. If the tree is healthy and growing well, meaning that it has a full crown and no obvious signs of decline, use Table 1 as the guide for determining the number of tap holes. If on the other hand, your trees are not healthy and declining, or if your trees look healthy, but there was a drought or significant insect defoliation during the previous summer, use Table 2 as your guide. If you are in doubt, be on the safe side and use Table 2.

Tap hole size – in order to collect sap you have to channel the flow out of the tap hole into some form of container. The size of the hole drilled into the tree is dependent on the type of spile chosen. There are many different types of spiles or taps on the market today, and a maple equipment dealer can help you decide which is appropriate for your operation. Traditional metal or plastic spiles are 7/16 inches in diameter; however, new spiles that are smaller in diameter are also available. In theory, a smaller diameter hole should help the tree in two ways. It should help reduce the time needed for the tree to heal itself by sealing off the hole with new wood. And, secondly, it should reduce the size of the stain column that develops internally as the tree compartmentalizes an area of wood behind the hole to protect it from infection. There are a number of ongoing studies to determine how these smaller spiles impact on tree health and sap flow. Currently the industry standard continues to be the 7/16-inch spile, although many producers are experimenting with the smaller diameter taps. If you choose to use the new type of spiles, continue to follow the appropriate tapping rule described in the previous section.

Tap hole location – it is also critically important to properly distribute tap holes around the tree. Avoid drilling within 15 cm (6 inches) horizontally and 60 cm (24 inches) vertically from any existing open tap hole. Try to avoid drilling tap holes when temperatures are well below zero. Cambial cracking can slow tap hole healing and reduce current and future sap flow.

Other tapping BMPs – keep the tap hole depth to a maximum of 2.5 inch or 6.4 cm; angle tap holes slightly upward (10 degrees from the horizontal); use only sharp drill bits which cut a clean hole; and don’t overset the spile into the tree (a gentle tap to ensure that it is set is all that is needed).

Collecting Sap

Sap needs to be collected and stored before it can be processed into maple syrup, and to do this you will need to use some sort of collection system. There are really only two main types: buckets and tubing or a combination of both.

Tubing – tubing systems connect each tap to a main or intermediate storage container. Tubing has been around since the 1950s and is now used commonly throughout the maple industry. Most large producers now use some form of tubing system to collect their sap. A tubing system can either be gravity driven, where sap exits a tree and flows downhill to a storage facility, or vacuum driven, where the air pressure inside the tubing is reduced, allowing for sap to exit the tree and flow (still downhill) to a pump where it is then redirected to a storage facility. Vacuums don’t actually suck the sap out of the tree as the name suggests. Sap flow, in part, is controlled by air pressure, and reducing air pressure allows sap to flow from the tree. In Part IV of this article I will discuss the mechanisms of sap flow.

One of the main benefits of using tubing is the reduction in labour needed to collect sap. Depending on the topographic layout of the sugar bush, a well-designed tubing system, even for the small-scale producer, can dramatically reduce the day-to-day activity associated with gathering sap. In addition, tubing can help minimize the chance of site and tree damage during the early spring, a time when the sugar bush is at its most vulnerable state.

A tubing system is hard to install, and depending on the layout of the sugar bush, can be initially quite costly to purchase. Each operation is different, and the reader is encouraged to seek the advice of experienced producers before purchasing tubing equipment.

Buckets – buckets have been around in one form or another since Aboriginals first discovered sweet maple sap. A metal spile (usually) with a hook on it is installed in a tap hole. The hook allows for the easy installation and removal of a bucket, which needs to be emptied frequently when the sap is flowing. Buckets come in any number of different sizes, shapes and materials. It is, however, critically important to ensure that the buckets are food grade, meaning that they are not contaminating the sap with unwanted substances like lead. Buckets work well when there are only a few; however, they can be problematic when you tap a large number of trees or when help is scarce. Driving through the sugar bush with a tractor and trailer also increases the chances of damaging the woodlot.

Processing Sap

Sap needs to be processed into maple syrup, and whether it is done on the kitchen stove or on a dedicated evaporator, it is important to size your operation to your needs and to the number of taps you are planning to install. The evaporator (or arch) looks like a complicated piece of machinery (and it can be); however, for the small-scale operator or hobbyist, it works on a very simple principle. Intense heat is applied causing the sap to boil, which removes most of the water and concentrates the sugars and other solids mentioned earlier.

Raw sap usually flows in at one end where it moves along a series of channels (baffles) until the sugars and solids have been sufficiently concentrated. This creates a density gradient between the unprocessed sap at the back of the pan (~ 2.5% solids) and the processed syrup at the front of the pan (66% solids). This is really the best way to make high-quality syrup; boiling in a pot or in a flat pan without baffles requires the reduced sap be constantly diluted with new sap as the water is removed. This reduces the grade of the final product, which can be very dark.

The modern evaporator comes in a number of different sizes and configurations. Again, it is a good idea to seek the advice of an experienced syrup producer before purchasing. It is critically important to size your evaporator to your current and future needs. The amount of time spent making syrup is a function of the number of taps and the size of the evaporator – undersize the evaporator or oversize the number of taps and it becomes very difficult to keep up with the sap flow. Long boil times can quickly reduce the enjoyment of making syrup and increase the potential for mistakes or accidents.

There are a number of good references that will help the novice producer work through the operational planning stage. One publication in particular, the North American Maple Syrup Producers Manual provides an all-encompassing discussion on processing raw sap into maple syrup.

Syrup Quality

Anyone who makes maple syrup wants to make the best quality product possible. It is important to understand that quality does not just mean good-tasting syrup, the product also has to be safe to consume. If you are planning to sell your syrup, there are a few additional requirements that you will have to meet – all syrup sold in Ontario must be graded and labeled according to the Farm Products Grades and Sales Act, Regulation 386. Maple equipment producers sell syrup grading kits and labels. Table 3 describes the current grading system used in Ontario.

Lead in Maple Syrup

While grading based on flavour, density and colour is important, it does not account for potential contaminants in syrup. Lead in particular has become a major public health concern for the maple syrup industry and for Ontario producers in particular. Health Canada sets health and safety standards for food products and has determined that there is no minimum safe level for lead. Lead is a potent toxin where even trace amounts can pose a health hazard to humans. This is especially true for children who can suffer severe nervous system and cognitive development problems.

Normal lead levels in maple syrup are low. However, the process of removing approximately 97% of the water from raw sap concentrates not only the sugars and organic molecules, which give maple its characteristic flavour, but the other undesirable trace elements like lead and other heavy metals. Lead contamination in maple syrup is introduced from two main sources:

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